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1982 , Volume , Issue Dec-1982

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1. Copr 1949 1998 Hewlett Packard Co Volume 33 January 1982 through December 1982 de JOURNAL Hewlett Packard Company 3000 Hanover Strest Palo Alto Califomia 94304 USA Hewlett Packard Central Maling Dept Van Heuven Goedhartiaan 121 1181 KK Amstelveen The Nethetands Hewlett Packard Canada Ltd 6877 Goreway Drive Mississauga Ontario L4V 1M8 Canada Yokogawa Hewlett Packard Ltd Suginami ku Tokyo 168 Japan PART 1 Chronological Index January 1982 Signal Processing Using Surface Acoustic Waves William R Shreve Retrofitting for Signature Analysis Simplified Robert Rhodes Burke A Fast Compact High Quality Digital Display for Instrumentation Applications Kunio Hasebe William R Mason and Thomas J Zamborelli February 1982 A Broadband Fully Programmable Microwave Sweep Oscillator Rolf Dalichow and Douglas E Fullmer A New Series of Programmable Sweep Oscillator Plug ins Gary W Holmlund Glenn E Elmore and Duaine C Wood Portable Defibrillator Monitor for Cardiac Resuscitation Paul I Bennett and Victor C Jones March 1982 High Performance Computing with Dual ALU Architecture and ECL Logic Frederic C Amerson Mark S Linsky and Elio A Toschi Dual ALU Micromachine Has Powerful Development Tools Rich ard D Murillo Powerful Diagnostic Philosophy Reduces Downtime David J Ashkenas and Richard F DeGabriele A High Performance Memory System with Growth Capability Ken M Hodor and Malcolm E W
2. HEWLETT PACKARD JOURNAL Technical Information from the Laboratories of Hewlett Packard Company DECEMBER 1982 Volume 33 e Number 12 Contents Extended Memory and Modularity Are Added to the Series 80 Computer Family by John T Eaton Andrew W Davidson and William R Frolik An extended memory controller makes it possible for these 8 bit systems to address and use more than one half megabyte of RAM Module Brings CP M to HP s Latest Series 80 Computers by Timothy V Harper Now you can run CP M based software on your HP 86 or HP 87XM Personal Computer Development of a Low Cost High Quality Graphics Plotter by Majid Azmoon This inex pensive plotter is easy to use and does not require periodic adjustments to maintain plot quality Controlling a Graphics Plotter with a Handheld Programmable Calculator by Robert M Miller and Randy A Coverstone The plotter is the 7470A The calculator is the HP 41C 1982 Index Low Cost Plotter Electronics Design by Neal J Martini David M Ellement and Peter L Ma Custom servo ICs and gate array logic circuits allow a single board design Plotter Drive Motor Encoder Design by Arthur K Wilson and Daniel E Johnson This compact optical encoder is installed inside the drive motor housing Graphics Plotter Mechanical Design for Performance and Reliability at Low Cost by Rich ard M Kemplin David M Petersen Chuong C Ta David C Tribolet and Robert J Porcelli A grit wheel paper drive low
3. a b 30 HEWLETT PACKARD JOURNAL DECEMBER 1982 they cross tension the paper as it is driven back and forth Fig 5 The manner in which the conical roller moves paper laterally toward its large diameter end depends on the fact that the rubber in the pinch roller is displaced sideways when pressed against the paper Fig 6a This creates a contact patch like that shown in Fig 6b Now consider a particle of polyurethane on the large diameter surface of the pinch roller As the pinch wheel rotates this particle comes into contact with the paper and traces out a path resembling that shown in Fig 6c As the particle moves out to its maximally displaced position it exerts a frictional force on the paper acting to the left Conversely as the particle moves back from its maximally displaced position it exerts a frictional force on the paper to the right But because of hysteresis in the polyurethane the sum of the forces acting to the right is less than the sum of those acting to the left Hence there is a net force to the left that is toward the large diameter end of the tapered roller Tapered pinch wheels have several advantages over con ventional methods of achieving paper flatness First ta pered pinch wheels are a low cost solution since paper flatness is achieved not by adding parts but rather by changing the shape of an existing component The tapered rollers can be easily fabricated by injection molding be cause their co
4. Ison Data Communications for the 9826A and 9836A Computer Sys tems Carl M Dierschow and Robert P Uhlrich June 1982 Laser Printing System Provides Flexible High Quality Cost Effective Computer Output James A Hall Six Steps to a Printed Page Robert R Hay Laser Printing System Architecture James T Langley Interactive Software for Intelligent Printers Kathleen A Fitz gerald Electrostatic Image Formation in a Laser Printer Erwin H Schwie bert and Paul R Spencer Laser Printer Image Development System Thomas Camis Laser Printer Fusing System Roger D Archibald Monitoring the Laser Printing Process Ronald A Juve and David K Donald Specialized High Speed Electronics for Document Preparation Flexibility Philip Gordon The People Who Made the Product Billie J Robison July 1982 Optical System Design for the Laser Printing System John R Lewis and Laurence M Hubby Jr Laser Printer Optics Control and Diagnostic Circuit Gary L Holland A Synchronous Mirror Motor Drive for the Laser Printer Gary L Holland Laser Printer Machine Control System James D Crumly and Von L Hansen Sensing Paper Jams Gary L Holland Solid State Microwave Signal Generators for Today s Exacting Requirements Donald R Chambers and Steven N Sanders High Performance Wideband Cavity Tuned Solid State Oscil lators Edward G Cristal Arthur N Woo Phillip G Foster and Ronald F Stiglich A Wide Dynamic Range Pulse Leveling
5. Lubin and E G Weaver Jr Handheld Scan ner Makes Reading Bar Codes Easy and Inexpensive Hewlett Packard Journal Vol 32 no 1 January 1981 4 D R Conklin and T L Revere III Reading Bar Codes for the HP 41C Programmable Calculator Hewlett Packard Journal Vol 32 no 1 January 1981 Robert M Miller Bob Miller joined HP after receiving a BS degree in computer science at California State Polytechnic University inlate 1980 He also has a BA degree in English literature awarded in 1973 by LaSalle College Pennsylvania The BB HP 41C Plotter Module was his first HP project and now he is a project leader for HP 75C application software Bob was born in Philadelphia Pennsylvania and now lives in Corvallis Oregon His interests include backpacking read ing swimming and playing volleyball Randy A Coverstone Randy Coverstone was born in Goshen Indiana and attended the University of Evansville Indiana receiving a BSME degree in 1975 After earning an MSME degree and the degree of Mechanical Engineer atthe Massachusetts Institute of Technology in 1978 he joined HP Randy worked on the chart advance for the 9872 Plotter which he discussed in an earlier HP Journal article and the servo design of the 7470A He is a visit ing lecturer on applied controls at the University of California at San Diego He is married has a new baby daughter and lives in San Diego California His
6. A servo controller IC supplied by HP s Corvallis Division is used to close the loop It provides the interface to the microprocessor decodes the encoder signals sums posi tion errors estimates velocity and sums it and transforms the servo error to a pulse width modulated output The velocity constant and PWM gain both IC mask programma ble were changed to adapt the original servo controller chip to this servo system The PWM output of the servo chip is processed in the gate array to provide an adjustable forward path gain ky There Charge Path To Motor Drivers o gt 4 To sv m Regulator To 5V Regulator o y DAS i To Motor mu zl Drivers i E p To 12V 5V Regulators Ee Fig 3 Charge pump circuits are used to supply negative voltages for servo and I O circuits a Hall wave pump for HP IB and HP IL versions of 7470A b Full wave pump for RS 232 CICCITT V 24 version 24 HEWLETT PACKARD JOURNAL DECEMBER 1982 Fig 2 Block diagram of servo system for each plotting axis in the 7470A Pulse width modulation PWM drivers are used because their switching action offers much greater efficiency than linear drivers This reduces power con sumption and heat generation are two reasons why it is necessary to adjust the gain First because the motor driver supply voltage is unregulated the forward gain k through the motor driver varies with its sup ply voltage
7. Arithmetic functions keyboard Oct Computer system CP M Dec Display list Oct Attenuator programmable Computer system modular Dec Display matrix Oct oscilloscope Sept Computer systems May Display module Jan Autocalibration Sept Computers personal Series 80 Dec Display time domain ses Autolocating circuit memory May Configuration menu printer May Display waveform recorder Nov Autoscope Sept Controller ac power Doa Donne OSEE Feb Autosequence measurement program Oct Controller SMU Oct Dual ALU architecture Mar Autoset waveform recorder Nov Control mode changing SMU Oct Convolvers SAW Jan E B Corona devices laser printer June ECG monitoring Feb Bar code plotting Dec Correlators SAW Jan ECL board test system Mar Baseband analysis Apr CPM system Dec ECL computer system Mar BASIC language system May CRT display design May Electromigration Aug Dec CRT modeling program Apr Electrophotographic printer June Beam recrystallization polysilicon Aug CRT mount Sept EMC extended memory controller Dec BCD to base 10000 arithmetic May Current ranging SMU Oct Encoder optical Dec Benchmark test computer May C V measurements Oct End of sweep detection Sept BDOS CP M system Dec CVD processing plasma enhanced Aug Endpoint detection plasma etching Aug BIOS CP M system Dec Etching plasma Aug Bipolar IC process high D Expansion storage oscilloscope Apr performance Sept DAC 16 channel
8. Because of the lower level of customization shorter development time can be expected along with significant savings Peter L Ma Peter Ma joined HP in 1978 and de signed the I O processor system for the 7310A Printer and the digital circuits and gate arrays for the 7470A He is a graduate of the University of Washing ums ton where he received a BSEE degree in 1978 and Stanford University where he received an MSEE degree in 1982 Peter was born in Hong Kong and grew up in Seattle Washington He is a high E fidelity audio enthusiast enjoys tennis i skiing and going to the beach and lives in San Diego California in development cost Based on the large amount of circuitry to be implemented in LSI form and the number of signal pins required two silicon gate CMOS complementary metal oxide semiconductor gate arrays were selected The silicon gate process provides the necessary performance level and the use of CMOS logic reduces power consumption to a very low level Of the two arrays chosen one is a 770 gate array and the other contains 1000 gates Both are housed in low cost 40 pin dual inline plastic packages These two arrays are the equivalent of 80 LSTTL ICs that would have re quired a current of 0 7A at 5V As a result the HP IB version of the 7470A contains only eleven digital ICs quite amazing consider ing its performance and capabilities Armed with the strategy of attempting to put every li
9. Integrated Circuit Process Albert S Wang and Irene V Pecenco Synthesizer Accuracy for Unsynthesized Microwave Sources V Alan Barber October 1982 Intelligent Instrument Streamlines dc Semiconductor Parameter Measurements Kohichi Maeda Jin ichi Ikemoto Fumiro Tsuruda and Teruo Takeda Programmable Stimulus Measurement Units Simplify Device Test Setups Susumu Takagi Hiroshi Sakayori and Teruo Takeda HQMOS A High Performance NMOS Technology Horng Sen Fu Roger To Hoi Szeto Anders T Dejenfelt and Devereaux C Chen MOS Device and Process Design Using Computer Simulations Soo Young Oh PART 2 Subject Index November 1982 Waveform Recording with a High Dynamic Performance Instru ment James L Sorden and Mark S Allen Designing a Ten Bit Twenty Megasample per Second Analog to Digital Converter Arthur S Muto Bruce E Peetz and Robert C Rehner Jr Measuring Waveform Recorder Performance Bruce E Peetz Arthur S Muto and J Martin Neil Time Base Requirements for a Waveform Recorder Steven C Bird and Jack A Folchi Display and Mass Storage for Waveform Recording Christina M Szeto and Michael C Detro December 1982 Extended Memory and Modularity Are Added to the Series 80 Computer Family John T Eaton Andrew W Davidson and William R Frolik Module Brings CP M to HP s Latest Series 80 Computers Timothy V Harper Development of a Low Cost High Quality Graphics Plotter Majid Azmoon Controlling
10. PACKARD JOURNAL 21 PART 3 Model Number Index HP 41C Programmable Calculator 8350A Sweep Oscillator HP 85A Personal Computer 8683A B Signal Generator HP 86A Personal Computer 8684A B Signal Generator HP 87XM Personal Computer 9130A Flexible Disc Drive 1345A Digital Display Module 14570A AC Power Controller 1727A Storage Oscilloscope 275 MHz 16058A Test Fixture 1980A B Oscilloscope Measurement System 19860A Digital Waveform Storage 2671A Printer 30142A 1M Byte Memory Module 2671G Graphics Printer 30143A IO Adapter Module 2673A Intelligent Graphics Printer 32460A HP 3000 Series 64 System 2680 Laser Printing System Processing Unit 78660A Defibrillator Monitor HP 3000 Series 64 Computer System 78668A Quick Mount Power Base 3724A Baseband Analyzer 82160A HP IL Module HP 41C 3725A Display 82184A Plotter Module HP 41C 3726A Filter Mainframe 82900A CP M System 4145A Semiconductor Parameter Analyzer 82901M Flexible Disc Memory 5001A BICID Microprocessor Exerciser 82937A HP IB Interface Module 5180A Waveform Recorder 83500 Series RF Plug ins 5181A Display Tape Storage Module 98261A Add on Language for 53448 Source Synchronizer 9826A 9836A Computers 6024A Autoranging DC Power Supply 98628A Data Communications Card 7470A Graphics Plotter PART 4 Author Index Allen Mark S Nov Fazarinc Zvonko Sept Landgraf Robert M Sept Rick David Amerson Frederic C Mar Fedraw Ken May Langley James T June Risley William B Archiba
11. Packard Jour nal Vol 33 no 10 October 1982 2 W D Baron et al Development of a High Performance Low Mass Low Inertia Plotting Technology Hewlett Packard Journal Vol 32 no 10 October 1981 3 Complete issue dedicated to 7580A design Hewlett Packard Journal Vol 32 no 11 November 1981 4 P H Dorward et al New Plotting Technology Leads to a New Kind of Electrocardiograph Hewlett Packard Journal Vol 32 no 10 October 1981 5 C C Lo Plotter Servo Electronics Contained on a Single IC Hewlett Packard Journal Vol 32 no 10 October 1981 Majid Azmoon Maj Azmoon joined HP in 1973 and worked on the 9872 7221 Graphics Plotters and 7245A Plotter Printer be fore becoming the R amp D project man ager for the 7470A His work has re sulted in two previous HP Journal arti cles and two patents related to the 7245A Maj was born in Tehran Iran and holds a BSME degree from Califor nia Polytechnic University 1969 and 4 the MSME degree from the University of Southern California 1971 He is mar i ried has a son and lives in Poway California His outside interests include playing racquetball piano and electronic music synthesizer and restoring old Ford Mustang automobiles CORRECTION In our November 1982 issue Fig 13 on page 26 had some incorrect labels The horizontal axes of the two time window plots on the left side of that figure should be labeled t not f On both side
12. San Diego division He was born in Newark New Jersey and served four years in the U S Air force Bob enjoys listening to Christian music is an avid reader and leads the singing at his church He lives in Es condido California is married and has two children David C Tribolet Dave Tribolet designed the pen change mechanism and X axis mechanics for the 7470A With HP since 1979 he is presently an R amp D project leader Dave was born in Tucson Arizona and received a BSME degree from the University of Arizona in 1978 Further studies at Stanford University have earned him the MSME degree in 1979 and the MSEE degree in 1982 Living in San Diego California Dave teaches a machine design course at the University of California at San Diego and likes basketball and sailing result was a hopelessly brittle part with cosmetic blemishes The U L requirement was satisfied in another way by modifying another part used to mount the trans former to enclose all line voltage components in a V O rated plastic Acknowledgments The successful development of the 7470A mechanics was ensured by the insights guidance and planning provided by Majid Azmoon Product reliability could not have been achieved without the extensive life strife and MTBF testing provided by Ned Bryant Charles Shinner and the reliab group Chuong C Ta Chuong Ta joined HP in 1979 and J worked on the X axis drive paper load ing
13. Sept Bitrigger Nov Data communications card May F Board tester ECL Mar Data control laser printer June Fast writing rate oscilloscope Apr Buried contact process NMOS Oct Data link radio Jan Flexible disc drive May Burn in testing May Defibrillation parameters Feb Filter chirp SAW Jan 20 HEWLETT PACKARD JOURNAL DECEMBER 1982 Copr 1949 1998 Hewlett Packard Co Filter slot Flicker of frequency noise process FM direct coupled for i generator FM wideband Forms design software Fractional N synthesis Fusing system laser printer G Gate arrays use in plotter electronics Gate MOS thin dielectric film Graphics display module Graphics plotter low cost Guard filter SMU GUEST ECL board tester H Hewlett Packard Interface Loop HP IB interface internal personal computer HP IL HPL language system HQMOS process Hysteresis control Image formation and development laser printer Instruction set test microprocessor Integrated circuits custom oscilloscope Intensity control automatic oscilloscope Interface n HP IL Interfaces internal personal computer Intermodule bus W O adapter VO architecture nonstructured 1O interrupt VO programmed L Laser printer Laser printing system Lens mounts laser printer Leveling loop Leveling microwave sweep oscillator Lithography optical Lithography X ray Lock and roll mode Dec May Nov Mar Mar May May May July
14. The solution to the optoisolator problem was to use a split bobbin pulse trans former similar in construction to the power transformer This provides physical separation between the logic cir cuits and the ac line If there should be a failure in the logic circuits the pulse transformer saturates and no more gate current flows Connectors The power connections to the 14570A posed a problem The initial solution was a barrier block but this had many problems Safety covers that are not permanently attached are frequently discarded and a way to make them captive eluded our best mechanical designer We felt that all the input and output cables required strain relief but fifteen cable clamps on the rear of the unit made wiring very difficult and required a 5 inch high box to accommodate them Screw connections made wiring in the rack inconve nient and changes in field wiring were time consuming The idea of using standard ac plugs and receptacles was rejected because the product is designed for 120 or 240 volt operation The connector that was finally selected has many advan tages Fig 4 Both male and female connectors have their mating surfaces and the screws for tightening the connec tions recessed from touch Each connector has built in strain relief The center ground pins are longer so they make contact first The connector was easily adapted for circuit board mounting The fact that the connector can be assembled to the fiel
15. This variation is too wide to maintain adequate performance without compensation Second below some threshold velocity the servo controller chip provides no velocity feedback This leaves the servo underdamped and enhances limit cycling Reducing the forward gain when the servo is idle reduces this effect Through the gate array the processor can control the forward gain and compensate for both problems Pen Lift The pen lift in the 7470A is actuated by a solenoid To minimize the size of the solenoid it is necessary to drive it first with one current to pull the plunger in and then with a smaller current to hold it in This is accomplished by a PWM voltage drive The PWM duration is set by the gate array logic One duty cycle is used for pulling in and another for holding These duty cycles are under micro processor control and are modulated to eliminate the effects of unregulated 24Vdc supply variations Power Supply Four voltages are generated by the power supply module Low current supplies provide the 12V and 5V required for the NMOS servo chips These supplies are also used in the RS 232 C CCITT V 24 version of the 7470A In addition there is a linear 5V supply The linear supply design is attractive because of its simplicity and can be used because the total 5V load current is low nominally 600 mA the CMOS gate arrays and the NMOS servo chips require very little power The fourth voltage is the unregulated 24Vde suppli
16. Vincennes In diana and is a graduate of Purdue Uni versity receiving a BSEE degree in 1980 He joined HP that same year was an R amp D engineer for the HP 86 and a production engineer for the 82901 Disc Drive and now is working on new prod uct design John served six years inthe U S Navy before attending Purdue He lives in Corvallis Oregon and enjoys backpacking folk dancing whitewater rafting and cross country skiing William R Frolik Bill Frolik received a BA degree in physics from Willamette University Oregon in 1979 and the BSEE and MSEE degrees from Stanford University in 1979 and 1980 respectively Hethen came to HP worked on the logic design team for the HP 87 designed the EMC for the HP 86 and HP 87 and now is involved with CMOS ROM design Bill is co author of one other article on the HP 87XM and lives in Corvallis Oregon where he was born His outside in terests include photography travel cycling skiing piano and computer programming Andrew W Davidson Andy Davidson was on the logic design team for the HP 87 and designed the memory modules for the HP 86 and HP 87 With HP since 1980 he now is a production engineer for Series 80 prod ucts Andy was born in Abington Pennsylvania and attended Clarkson College of Technology New York earn ing a BS degree in electrical and com puter engineering in 1980 He is mar ried and lives in Corvallis Oregon Andy enjoys jogging going t
17. an interactive plotting program that can plot functions or any arbitrary set of points with minimum over head The program prompts the user for 1 the name of a user program that given an X coordinate will compute the Y coordinate 2 scaling information and 3 either the number of points to be plotted or the increment between points to be plotted At that point the user can examine and edit any or all of the data base The user can specify the placement of the X and Y axes the number of major and minor tics per axis and the number of labels per axis Data buffers can be created edited and plotted Other built in features allow the user to alter the line type and pen used for plotting and to do scatter plots It is also possible to change one or more parameters of the plot and then to redo the complete plot with one keystroke Acknowledgments Thaddeus Konar was primarily responsible for the bar 18 He Fig 4 Bar code functions and powerful user language programs given in the 82184A Plotter Mod ule s user manual make it easy to obtain plots of bar code programs as shown code plotting commands Dave Conklin provided ideas and guidance throughout the project References 1 S Harper C Landsness and R Quick Interface System Weds Instruments to Small Computers Electronic Design December 24 1981 pp 78 93 2 R Katz The Hewlett Packard Interface Loop HPIL Byte April 1982 pp 76 92 3 JJ Uebbing D L
18. and a garter spring The stable housing positions the pen and provides structural support for the other stable components The stable arm holds the pen against the stable housing The capper arm seals the pen nib from ambient air and is actuated by a ramp built into the pen holder The garter spring holds the stable arm in place and provides the pen holding and capping forces The stable housing stable arm and capper arm are injection molded to minimize cost The pen holder assembly consists of two pen holder arms a garter spring and the pen holder itself The pen holder arms position the pen against the pen holder while the garter spring provides the pen holding force to both arms The pen holder positions the pen and provides struc tural support to the other pen holder elements Fig 8 illus Fig 8 Pen pick a through c and pen park d through f sequences showing interaction between pen holder arm and the pen stable arm DECEMBER 1982 HEWLETT PACKARD JOURNAL 31 Copr 1949 1998 Hewlett Packard Co vais e AB cD DC BA Fig 9 Location of pen carriage stall positions A B C and D defined in text along the Y axis trates how the various pen changer components interact during a pen pick Fig 8a to 8c and during a pen park Fig Bd to 8f The intermeshing arm concept illustrated in Fig 8 was first used in the HP 7580A Drafting Plotter but in a unidirectional configuration Pen Sensing In multipe
19. circuits modify the pulse widths to adjust the servo gain to compensate for power supply variations and stabilize the slow axis movement As the mechanical sys tem moves optical encoders see article on page 26 mounted on the back of each dc motor send back digital pulses to the servo chips to close the servo loops Regulating the motor supply voltage would have been a duplication of effort because the servo already modulates this voltage usually to an average value less than full sup ply voltage It is less expensive to adjust the servo gain to compensate for power supply variations For the gate array logic to know how much to change the servo chip pulse width the microprocessor must know the level of unregu lated voltage supplied to the motors A voltage sensing circuit consisting of a 1 bit analog to digital converter provides this data The output of the converter also serves the dual purpose of controlling the front panel error light The servo system Fig 2 was modeled as a third order system with two state feedback The electrical time con Fig 1 Block diagram of elec tronic system for the HP 7470A Graphics Plotter Most of the sys tem logic is implemented by two custom gate array ICs DECEMBER 1982 HEWLETT PACKARD JOURNAL 23 Copr 1949 1998 Hewlett Packard Co stant of the dc motor is such that it could not be neglected However adequate performance is achieved with only po sition and velocity feedback
20. connected to the handshake lines of the memory card This is used to pace the readings taken by the memory card The pulse train card is set to provide 4095 pulses with a period of 10 microseconds allowing over 40 milliseconds of 69771A Digital Input Card Fig 2 This system is used for production testing of the 14570A AC Power Controller Another 14570A switches ac power to the unit under test Copr 1949 1998 Hewlett Packard Co data to be stored The puise train card is triggered when all the Channels on the 14570A are programmed to close After 4095 data points have been acquired they are sent to the HP 9826A Desktop Computer for analysis Transitions on the 12 channels are found by comparing each data point with the previous one If it is the same then no transition occurred during that ten microsecond interval If any data point is different from the previous one the twelve bits are EXCLUSIVE ORed with the last point to determine which bits are different When the times of the transitions are known it is simple task to calculate the operate and bounce times for each relay This method calculates these values for the 12 relays simultaneously using a single set of hardware Since we were concerned with operator safety we wanted to tum the power off when the unit under test was being connected to the ac ine or removed from tt It was also necessary to connect the unit to either 115 or 230 volts For t
21. drive up to two HP 91304 flexible disc drives and a Centronics compatible printer di rectly with its built in interfaces Video output is displayed on an external monitor Both 9 in 82912A and 12 in 82913A monitors are available from HP nucleus of phanumeric line labels and multicharacter variable names allow the programmer to use more meaningful names The programmer can also use spaces to indent portions of pro gram listings and make them easier to read and understand These spaces are retained by the HP 86 and HP 87XM for future program listing and storage With larger CRT displays the new Series 80 computers can support a larger number of user defined softkeys so the number is increased from the eight on the HP 85 to four teen These are also enhanced by making them default typ Fig 3 The HP 87XM Computer is the premier member of the Series 80 family It features a built in CRT display and an HP IB interface for communication with drives printers and plotters large 128K bytes internal user memory can be expanded up to 640K bytes by adding RAM mod ules to its four expansion ports Copr 1949 1998 Hewlett Packard Co ing aids when the new computers are in the calculator mode Fourteen commonly used commands can be dis played on the screen at a touch of a key The user need only type in the parameters and press the ENDLINE key for the command to be executed These aids can also be redefi
22. low cost alterna tive to manufacturing these parts in house Reliability Low maintenance cost is essential for a low cost device This objective should be achieved with high product relia bility Most of the low cost approaches listed above sub stantially increased the reliability of the plotter as well Extensive thermal modeling and mapping were con ducted in the early phases of the design to ensure that heat dissipated inside the package would not significantly affect the reliability of the components Several strife tests were performed to improve the plotter s reliability A strife test involves operating many units at maximum performance while the units are undergoing extreme temperature cy cling The temperature was cycled between 5 C and 60 C with each full cycle taking eight hours As a result of these tests many design weaknesses were discovered and sub sequently corrected Acknowledgments The success of the 7470A is a tribute to the excellence of the design team and manfacturing support group The au thor would like to thank Norm Johnson for his leadership Myron Hunt and Bryan Butler for their product marketing contributions and Dave Leong and Lynn Palmer for their product design efforts Special thanks go to the R amp D lab and the IC group at HP s Corvallis Division and to HP Laboratories References 1 K Maeda et al Intelligent Instrument Streamlines dc Semiconductor Parameter Measurements Hewlett
23. moves along the rod for Y axis displacement and rotates about the rod for Z axis movement Mounting the pen holder on the rod instead of the carriage the second main part of the slider block reduces the number of interfaces locating the pen to the platen thus reducing rotational deadband The carriage of injection molded Delrin A F rides on both the slider rod and a parallel hard anodized Teflon coated aluminum extrusion see Fig 1 and Fig 2 A com pression spring placed between the carriage and the pen holder coaxial with the slider rod preloads these parts together removing deadband without increasing Y axis friction An acetal homopolymer containing 20 poly 28 HEWLETT PACKARD JOURNAL DECEMBER Pen Holder gt gt Y es do U b fud Slider Rod j Axial Preload Spring Silicone Diaphragms Fig 1 Exploded view of slider block assembly used to trans port the pen along the Y axis of the 7470A Graphics Plotter Tension in the drive belt is maintained by a spring loaded tensioner ramp on which the idler pulley shaft rests see Fig 3 The ramp shifts to compensate for changes in belt length caused by temperature or creep but a low ramp angle and friction prevent the spring from entering the Y axis dynamic system The tensioner and idler pulley are retained by belt tension and the spring The belt attaches to the slider block by looping around a half gear detailed in the carriage rel
24. of California at Berkeley and joined HP shortly after Besides his work on the 7470A he developed the 7245A s power supply David was born in Buf falo New York and is a member of the IEEE He is married has one daughter and lives in Escondido California When not busy improving his mastery of the local Spanish dialect David enjoys Soccer cross country skiing and boul dering DECEMBER 1982 HEWLETT PACKARD JOURNAL 25 Copr 1949 1998 Hewlett Packard Co Neal J Martini Neal Martini hi 1978 and was the e leader for the 7470A BSEE degree from th troit in 1969 and the the University of Mis 1971 been with HP lectronics pro married has tw ANM Commu Acknowledgments Special thanks to the following for their contributions to the 7470A development Dave Paulsen and Janie Chintala for their outstanding software contributions Gary Skrabatenas for his motor driver and power supply designs Richard Murray for his work in the I O area of the 7470A Keith Cobbs for his analysis and testing of the servo design Dee Setliff for her contributions to the RS 232 C code de velopment and Bruce Jenkins for his help in following through with the HP IL version of the 7470A Reference 1 C C Lo Plotter Servo Electronics Contained on a Single IC Hewlett Packard Journal Vol 32 no 10 October 1981 Plotter Drive Motor Encoder Design by Arthur K Wilson and Daniel E Johnson The 7470A Gra
25. systems where interference can t be tolerated and 50 000 operations the lifetime of a typical relay may occur in six months R P Dolan Editor Richard P Dol her Arvid A Danielson e Illustrator Nancy S Vanderbloom Administrative Si 3 e European Production Supervisor Henk Van Lammeren 2 HEWLETT PACKARD JOURNAL DECEMBER 1982 OHewlett Packard Company 1982 Printed in U S A Copr 1949 1998 Hewlett Packard Co Extended Memory and Modularity Are Added to the Series 80 Computer Family HP s newest Series 80 computers the HP 86 and HP 87XM provide memory capacities up to 640K bytes different combinations of built in interfaces and for the HP 86 a modular system configuration by John T Eaton Andrew W Davidson and William R Frolik the first member of the Series 80 computer family It was designed to aid the scientist or engineer in collect ing analyzing storing and displaying data With its own internal tape drive printer display and four expansion ports the HP 85 provides effective portable solutions to many data processing problems The Series 80 family is now expanded by two new mem bers the HP 86 and HP 87XM These computers perform all the workstation nonportable functions performed by the HP 85 and many business functions not previously avail able from Series 80 products The block diagrams of these two new computers are basically the same differing only in the amount of inter
26. testing with actual molded parts would be essential Many of the critical molded parts were tooled with temporary molds before strife and reliability testing to allow test results to be meaningful The most critical of the tem porary molded parts was the heart of the plotter the chassis This major structural part hoids the dc drive motors shafts extrusion and idler and acts as the writing surface for the paper The large temporary mold for the chassis went together like a three dimensional jigsaw puzzie There was some uncertainty about molding such a large part and still being able to maintain the critical dimensions However the first prototype mold yielded a successful part Having these molds also allowed making more prototype plotters to test at a reasonable cost Assembly Line To meet the automatic assembly line objective four alternatives were proposed Two of the proposals included the use of carousels and two included transporters The assembly line ap proach chosen was to achieve the following Reduce the labor to build the plotter by having the assemblers spend more time assembling and less time moving parts Reduce the amount of space required to assemble the pro jected high volume Let the assemblers work at their own pace while providing a Serious production atmosphere An economic study was made and then an assembly line that uses one progressive assembly carousel flow racks roller inter change an
27. the triac Solid state switches can withstand large current surges but there is a limit to the di dt that they can withstand This is because it takes a finite length of time for the current to spread so that the whole semiconductor die can share the load current If the current rises too rapidly localized heating on the die can destroy the device With the circuit arrangement of Fig 2 the triac will turn on and off each half cycle of the 60 Hz ac line The large di dt results ina 120 Hz signal that is very rich in high frequency harmonics On turn off solid state relays perform more like an ideal switch The triac will remain on for each half cycle until the load current is less than the latching current of the triac When the source of the trigger current is removed the triac will turn off at the next zero of the load current There is a problem when the load is inductive When the current is almost zero the voltage may be near its peak When the triac ceases conduction the full line voltage may appear across the open switch almost instantaneously This large dv dt can be coupled through parasitic capacitance to the gate of the triac causing it to turn on again To guard against this dv dt problem an RC snubber network is placed across the switch The value of this snubber should be tailored to the load If the snubber impedance is too low excessive load current will flow through it if its impedance is too high the triac will fire bec
28. was split into modular subassemblies to simplify and reduce labor This breakdown of the product into major modules such as the motor encoder as sembly power module assembly mechanics and printed circuit board made it easy to assign to each of the manufacturing en gineers one part of the product to improve As mentioned on page 15 machined parts painted or finished parts interconnect ca bles assembly line adjustments and a cooling fan were consid ered undesirable Although total success was not realized in avoiding all of these their use is only about 25 of what it might have been Molded Parts The manufacturing team realized that because the product Five internal character sets English Math French and German Scandinavin and Spanish Text can be written in any direction with or without character slant and in many sizes Seven built in dashed line fonts and symbol plotting capability make it easy to design understandable graphs Forty two built in HP GL Hewlett Packard Graphics Language commands HP GL software written for other HP plotters can be easily adapted to the 7470A Addressable step size can be as small as 0 025 mm Re peatability to a specified location is 0 1 mm with any given pen and 0 2 mm from pen to pen Pen acceleration is approximately 2g and plotting speed is programmable in 1 cm s increments from 1 to 38 cm s Labels and annotations can be drawn at speeds up to 5 had many molded parts extensive
29. was to try to eliminate all of the 74LS series ICs from the printed circuit board This has many attractions A custom LSI IC saves a tremendous amount of board space Substantially less power is required from the power supply and less heat is generated Electromagnetic compatibility requirements can be met more readily because the radiation caused by the relatively short rise and fall times of LSTTL signals and many interconnecting traces on the printed circuit board are eliminated Gate Arrays After the decision was made to develop a custom IC we had to select between the different technologies available The selection process was based on many important factors that include per piece part cost development cost development time expected volume circuit complexity reliability and design risk A fully custom NMOS n channel metal oxide semiconductor integra tion effort was considered This approach promised relatively low part cost using proven technology and design methods How ever the very high development cost and lengthy development lime could not be justified at our projected moderate volumes We turned to another approach semicustom gate arrays which are rapidly gaining in popularity Gate arrays are integrated circuits prefabricated in wafer form up to the final processing steps These wafers are then customized at the metal masking stage by applying a unique interconnect pattern to implement the logic design
30. 14570A is not recommended for this application Relay Considerations With these constraints the relay characteristics were es tablished The relay must operate in less than one half ac line cycle and release in less than one fourth cycle The relays investigated would do this but with little time to spare It was found that by operating the relays at a higher than nominal potential pull in could be speeded up con siderably This had the undesirable effect of slowing their release time because of increased energy stored in the relay coil This approach also made them less reliable because of increased power dissipation The solution isto charge a small capacitor up to twice the nominal voltage of the relay This charge is used to switch the relay rapidly while the current to hold the relay is DECEMBER 1982 HEWLETT PACKARD JOURNAL 37 Copr 1949 1998 Hewlett Packard Co The production test set for the 14570A checks all the normally tested parameters such as high and low line operation off state leakage current and isolation In addition it checks the operate and release time on each relay in the working unit This is done by observing the voltage drop across the relay Since the SCR has about a 1 6 volt drop and the relay drop is only a few hundred millivolts it is very easy to distinguish between relay conduction and SCR conduction It is also easy to see the relay contacts bouncing when the SCR and relay are alternat
31. By not using the HP IB the HP 86 system is able to lower the cost of mass storage capability If the HP IB is required for other devices such as plotters or instruments an 82937A HP IB Interface Module can be plugged into any free expan sion port in the HP 86 s back panel Although the HP 86 internal interfaces and external de vices are different from those used by the HP 87XM the two mass storage systems are completely software compatible The HP 86 interfaces are designed to emulate an HP IB with a dual disc drive and printer on it An HP 86 user sees what looks like an HP IB card with a dual disc drive at address 0 and a printer at address 1 Additional flexible disc or even hard disc drives can be added by plugging an HP IB inter face card into one of the HP 86 s four expansion ports Normally all Series 80 I O is done through interface cards which communicate with the CPU using an integrated cir cuit called a translator chip An I O card contains a mi crocomputer that is programmed to talk to the CPU using an I O protocol and operate an external interface bus For example the CPU orders an HP IB card to send commands and data over the bus to a disc drive Another processor at the disc drive receives the commands performs them and passes the results back to the CPU In the HP 86 a single microcomputer is used to do disc and printer operations It talks through the translator chip with the CPU and emulates the I O card protocol It
32. Circuit Board Copr 1949 1998 Hewlett Packard Co LED Holder n BS Phase Plate N Su Photodiode Holder O gt N Printed Circuit Board 3 k Photodiode Array Fig 2 Exploded view of encoder s optical and electronic assembly after the optics assembly has been mounted Custom components such as special resistor networks where applicable This saves considerable space on the printed cir cuit board has a lower net cost and reduces lead lengths in low level signal areas minimizing electrical interference prob lems Standard components with standard tolerances when possi ble For example using standard size composition resistors with 5 tolerance reduces both material cost and by making it Possible to use automatic insertion machines labor cost Test and assembly tooling to minimize assembly time For example the printed circuit boards are fabricated loaded and tested ten at a time Then during final assembly the encoder is adjusted to 10 degree phase accuracy using a specially designed test fixture To meet the high reliability objective the encoder design Fig 2 uses the following A single light emitting diode for the light source A custom detector consisting of a single monolithic chip with four matched photodiodes driven in the short circuit mode A dual operational amplifier to drive a voltage comparator on olerant code wheel to d
33. He came to HP in 1970 and has made contributions to the 7040 l family of X Y recorders and more H recently the optical encoders for the 7470A Dan has written one other article for the HP Journal and is a member of the IEEE and vice president of the San Diego chapter of the California Society of Profes sional Engineers He is married has two sons and lives in Poway California When he is not busy coaching Youth Soccer and Little each channel League Dan enjoys travel camping reading sports and playing Collimated see through method of light sensing that allows for in HP s local softball league DECEMBER 1982 HEWLETT PACKARD JOURNAL 27 Copr 1949 1998 Hewlett Packard Co Graphics Plotter Mechanical Design for Performance and Reliability at Low Cost by Richard M Kemplin David M Petersen Chuong C Ta David C Tribolet and Robert J Porcelli HE MECHANICAL DESIGN of a graphics plotter is a major factor in determining the plotter s cost per formance and reliability Although digital elec tronic techniques can replace the majority of mechanisms such as cams springs dashpots and limit switches used in earlier plotters for control functions paper handling and pen positioning must still be done mechanically The plotting and pen handling mechanisms used in the 7470A Graphics Plotter are designed simply with a minimum of parts yet provide reliable high quality out put Movement along each plo
34. In the articles on pages 12 23 and 27 you can read about the problems its designers had to solve to provide the quality people expect of HP products at the 7470A s very low price But the full significance of the 7470A isn t just its low price Its full significance is illustrated by the photograph on page 16 which shows the 7470A being driven by the HP 41C Personal Programmable Calculator When Chuck Tyler and his group at Hewlett Packard Laboratories began working on their new plotting technology several years ago they were motivated by the vision of a plotter for the pocket calculator owner s other pocket While that goal hasn t been realized a major milestone has been reached You can now get high quality multicolor ink on paper graphic output from a battery powered calculator What makes it possible is the Hewlett Packard Interface Loop or HP IL a new interface system for battery powered devices We re planning to cover the technical aspects of the HP IL in next month s issue By the way the HP 86 and HP 87XM are both compatible with it too Switching ac power on and off may seem simple we do it every time we turn on a light But if you re concerned about electromagnetic interference or need a switch that ll operate a million times before it wears out you have some problems The article on page 34 describes a new ac power switch Model 145704 that s designed for ten years of service switching power on and off under computer control in automatic
35. June July Apr Feb Aug Aug Sept Machine control system laser printer July Oct Manually tuned signal generators Manufacturing design for low cost Marker sweep Memory controller extended Memory mapping Memory multiplexed system Memory program checking Memory system cache Metallization IC Metallization IC Mo Au Microcircuits custom oscilloscope Microcircuits signal generator Microgrip plotting technology Microprocessor development tools Microprocessor exerciser for signature analysis Dec Feb Dec May Apr Apr Mar Aug Sept Sept July Dec Mar Jan Microwave source stabilization Microwave sweep oscillator Mixer Schottky diode ring Modeling IC processing and device design Modular computer system Monitors process laser printer Motor drive synchronous Multiband sweep circuit Multilingual computers Multiplier YIG tuned N Narrowband device testing NEWPLOT program HP 41C NMOS process scaled down Noise source o Operating system laser printer Operating system menu driven Optical system laser printer Oscillator stabilization microwave Oscillator sweep microwave Oscillators wideband cavity tuned Oscilloscope measurement system Overlay mode in microprocessor testing Oxidation silicon high pressure Oxidation silicon zero encroachment process Oxide isolation bipolar IC P Paper jam sensing laser printer Paper tensioning pinch rollers Par
36. Scheme James F Catlin Microwave Solid State Amplifiers and Modulators for Broadband Signal Generators Kim Potter Kihlstrom August 1982 Viewpoints IC Process Technology VLSI and Beyond Frederic N Schwettmann and John L Moll Optical IC Lithography Using Trilayer Resist Michael M O Toole E David Liu and Gary W Ray Silicon Integrated Circuits Using Beam Recrystallized Polysilicon Theodore I Kamins X Ray Lithography Garrett A Garrettson and Armand P Neukermans Dry Etching An Overview Paul J Marcoux Thin Films Formed by Plasma Enhanced Chemical Vapor Deposi tion Dragan B Ilic Electromigration An Overview Paul P Merchant SWAME A Zero Encroachment Local Oxidation Process Kuang Yi Chiu High Pressure Oxidation William A Brown DECEMBER 1982 HEWLETT PACKARD JOURNAL 19 Copr 1949 1998 Hewlett Packard Co September 1982 Oscilloscope Measurement System is Programmable and Auto ranging William B Risley Designing the Oscilloscope Measurement System Russell J Hard ing Monte R Campbell William E Watry John R Wilson and Wilhelm Taylor Development of the 1980A B Oscilloscope Measurement System Zvonko Fazarinc and William B Risley Digital Waveform Storage for the Oscilloscope Measurement System Eddie A Evel and Robert M Landgraf Putting the Measurement System on the Bus Michael J Karin Mechanical Design of the Oscilloscope Measurement System John W Campbell A High Performance Bipolar
37. Sept Pottinger John R ABE Woodtatfs Bim W Eaton John T Dec Kemplin Richard M Dec Woodward Mik E me rod Aus Kihlstrom Kim Potter mis n Gay Aug 5 lement David M ec Kohli Manm Mar r Robert C Jr jov Elmore Glenn E Feb Kwinn Kathryn Y May Rhodes Burke Robert ja ame Thomi Evel Eddie A Sept Rhymes Lynn Feb 22 HEWLETT PACKARD JOURNAL DECEMBER 1982 Copr 1949 1998 Hewlett Packard Co Feb July Dec Dec Oct Sept Mar Mar Feb Feb Dec Dec Dec Dec Feb May May Low Cost Plotter Electronics Design by Neal J Martini David M Ellement and Peter L Ma had to be designed as inexpensively and ruggedly as possible to remain consistent with the philosophy of a low cost high performance high reliability product The basic guidelines for the design were to use a single printed circuit board for the entire electronic system minimize overall parts count eliminate the need for a cool ing fan and use custom and semicustom electronics with high performanceicost ratio wherever possible Fig 1 is a block diagram of the electronic design of the 7470A All of the circuitry is contained on a single two layer printed circuit board 178 mm wide and 298 mm long The plotter intelligence is provided by a 1 MHz 6802 mi croprocessor an 8K x8 ROM and a 1K x8 RAM Some of the main functions controlled by the program code stored in the ROM are a Servo vector generation an
38. a Graphics Plotter with a Handheld Programmable Calculator Robert M Miller and Randy A Coverstone Low Cost Plotter Electronics Design Neal J Martini David M Ellement and Peter L Ma Plotter Drive Motor Encoder Design Arthur K Wilson and Daniel E Johnson Graphics Plotter Mechanical Design for Performance and Reliabil ity at Low Cost Richard M Kemplin David M Petersen Chuong C Ta David C Tribolet and Robert J Porcelli An Improved ac Power Switch Raymond A Robertson Subject Month c Deflection plates distributed Apr A Calibration continuous vertical Sept Delay lines dispersive Jan Acoustic devices surface wave Jan Calibration front panel Sept Detector selective Apr ac power controller switch Dec Cardiac resuscitation Feb Development system dual Advanced terminal processor Mar Cavity tuned oscillators July _ ALU computer Mar Airflow monitor Feb Cavity tuned signal generators July Diagnostic philosophy Mar Amplifier microwave power Feb Character design software june Digital CRT display module Jan Amplifier programmable gain Apr Clock skew control Mar Digital waveform storage sus Amplifier tracking calibration Apr CMOS latch up prevention Aug i d Analog to digital converter Oct Computer simulation MOS E Directed beam CRT display module Jan Analog to digital converter processidevice Oct Discharge current control Feb 20 MHz 10 bit Nov Computer system Mar Display and control system Apr
39. ads This timing is also suitable for resis tive loads since the relay can turn off in less than one fourth cycle This includes nonlinear resistive loads such as heat ers or tungsten loads Another common type of load is power supplies Switching power supplies might seem to be capacitive buta little analysis shows that they are not At turn on they present almost a short circuit while the filter capacitors are being charged This requires a switch that can withstand high surge currents such as a 14570A After one line cycle the input capacitors are charged and look more like a battery load drawing current only during that part of the line cycle when the line voltage is greater than the capacitor voltage This time depends on the amount of droop that the input capacitors have A circuit composed of rectifiers and capacitors the input to a typical switching power supply does not have a leading power factor Put ting a transformer in front of this the input to a typical linear supply makes little difference Because the load current starts to lead in the case of a capacitive load the relay has to turn off faster to ensure that the load current has not gone negative before the relay contacts open In practice the 14570A is capable of han dling a leading power factor of about 0 8 A capacitor start motor may havea leading power factor at start up however while running it is inductive and the 14570A has no prob lem turning it off The
40. age detection circuit and gating to prevent the switch from firing except near the line zero However even in these circuits the current to fire the triac is derived from the same source as the load current in fact the trigger current flows through the load Therefore the zero voltage window has to be set high enough for the line voltage to exceed the drop caused by the gate voltage the drop in the load and the drops in the gate current limiting resistor and diode bridge There is a further complication in that the triac has a latching current This is the current that must flow through the triac to ensure that the current will con tinue to flow after the gate current has been removed The zero voltage window must be of sufficient magnitude to accommodate the voltage drops and yet allow the load current to exceed the latching current of the triac Load current in an inductive load builds slowly and triacs have a nonsymmetrical gate firing characteristic When the zero voltage point is set too low a small inductive load is likely to turn on only for alternate half cycles To guard against this the zero voltage window for most solid state relays is set at 25 to 80 volts Solid State Switch Operation Triacs turn on very rapidly If a load such as a tungsten lamp which has a high inrush current is turned on at moderate line voltage there is a large rate of change of current di dt in the switching device This causes EMI and may damage
41. all vendors guarantee that their devices will withstand this breakover firing Possible solutions include metal oxide varistors across the switches for overvoltage protection and normal mode filters to re duce line spikes to solve the dv dt problems Another problem with solid state switches is the power they dissipate Most of this power loss is caused by the voltage drop across a solid state device in its on state This power loss causes thermal work hardening of the solder that holds the die to the header This can result in increased thermal impedance that can lead to thermal runaway Many devices are rated for as few as 25 000 thermal cycles In an application where the solid state relay reaches its maxi mum operating temperature during each on cycle it may havea life that is only one half as long as an electromechan ical relay Relay Switching Electromechanical relays have been used as ac power switches for a long time They are close to an ideal switch when they are in either the on or the off state but when switching their behavior is less than ideal A small power relay that can survive 1000 volts across its open contacts is much more common than a medium power triac that will withstand the same voltage The same relay might be rated at 5000 volts from coil to contacts It is difficult to imagine a switching device that is better than a well mated pair of relay contacts Relays suffer from two main problems turning on and turn
42. allel ripple ADC Partitioning to reduce propagation delay Pascal language system Phase noise oscillator Photoconductor drum laser printer PLOTBC program HP 41C Plotter ROM HP 41C Plug ins microwave Polysilicon transistors MOS Position sensing pen carriage stall Postobjective scanning Post trigger delay Pretrigger delay Power controller switch ac Powerfail option Power reference RF Power sweep Preobjective scanning Printer graphics Printer laser Print spooling CP M system Protocols interface Pulse leveling scheme R Reactors plasma etching Receiver design Recorder waveform Reflective array compressor SAW Remote computer diagnosis s Sampling repetitive and single sweep Schmoo plot Selective level measurement Series 80 computer family Copr 1949 1998 Hewlett Packard Co Sept Feb Apr June July Feb Sept Dec Apr July July Sept Feb July Sept Jan Aug Aug Sept July Dec Nov Mar May Nov June Feb Aug Dec July Nov Nov Dec May July Feb July May June May July Aug Nov Jan Sept Oct Apr Dec Servo graphics plotter axes Signal generator manual 2 3 6 5 GHz Signal generator manual 5 4 12 5 GHz Signal processing SAW Signature analysis retrofitting for Silicon oxidation Silicon oxynitride films Solid state switch Source synchronizer microwave Spectrum analyzer use with waveform
43. also operates the disc drive s When the CPU orders it to send data or commands to a disc the microcomputer stores them in memory and then performs the requested operation The CPU does not know or care whether it is using a full HP IB and external disc drive system or the emulated system because it uses exactly the same command sequence in either case The interface also recognizes when data is being sent to a printer and outputs the data on the Centronics compatible connector on the back panel of the HP 86 Acknowledgments Many contributions are needed to develop products like the HP 86 and HP 87XM Wan Cheng Chan designed the CRT controller Robert Orozco Lori Cook and Ching Chao Liu wrote the BASIC language interpreter Joe Sikich did the logic design Jim Bausch designed the CRT electronics and power supply Ching Chao Liu conceived the EMC scheme Ella Duyck designed the packaging and Mike Moore developed the XM version of the HP 87 Jerry Erickson was the HP 87 project leader Cliff Cordy designed the HP 86 power supply Lonnie Ford was responsible for the video monitors and Tom Pearo designed the HP 86 packaging The project leader for the HP 86 was Clement Lo References 1 Complete issue six articles Hewlett Packard Journal Vol 31 no 7 July 1980 2 TR Lynch A Custom LSI Approach toa Personal Computer Hewlett Packard Journal Vol 31 no B August 1980 John T Eaton John Eaton was born in
44. amic contactarea shown in b with the paths of particles on the c surface of the roller indicated These paths result in a net force to the left as shown DONNE Af FAAA Copr 1949 1998 Hewlett Packard Co suited to plotters with only one axis of carriage motion However pen turrets tend to be somewhat expensive Off carriage pen arrays are likewise capable of storing a large number of pens but require two axes of carriage motion On carriage pen arrays burden the carriage with extra mass which compromises servo performance In addition more than one pen holder on the carriage introduces tolerances from holder to holder Hence some degree of repeatability from pen to pen is sacrificed Since none of the existing schemes for achieving multi pen plotting seemed well matched to the 7470A s low cost product objectives a different approach was taken The basic configuration is shown in Fig 7 The main elements of the pen changing mechanism are the left pen stable the right pen stable and the pen holder assembly Each stable houses one pen and caps the nib to prevent drying Note that the pen stables are mirror images of each other and the o gt gt c 9 Fig 7 Basic Y axis configuration showing the pen carriage and location of the two pen stables pen holder assembly is symmetrical Each stable consists of four components the stable hous ing the stable arm the capper arm
45. and HP 87XM so that to CP M it appears as an Hewlett Packard Interface Bus HP s implementation of IEEE Standard 488 1978 Fig 3 Block diagram of elec tronics for the 82900A CP M Sys tem Module Copr 1949 1998 Hewlett Packard Co ESCape key Another nice feature is that the HP 86 and HP 87XM can have more than 400K bytes of memory less than the maximum possible because the CP M system mod ule occupies one of the four mainframe ports The binary executive for CP M occupies 4K bytes of the mainframe RAM Although CP M cannot access the rest of the main frame memory directly the binary executive makes it look like a printer so that files can be printed from this memory buffer at the same time that other CP M activities are taking place Complete control is provided over this print buffer through the use of another key on the HP 86 and HP 87XM that CP M does not use Pressing the PAUSE key toggles the printer on and off and pressing STEP SHIFT PAUSE deletes the print buffer completely All of this occurs without af fecting CP M operation The third piece of software the boot ROM is simple in function but vital for initializing the system properly The code transfers itself into high RAM and executes a test of low RAM The boot code is then placed in its proper loca tion and tests the remainder of the RAM After determining that the 82900A Module is functional the code reports to the Series 80 mainframe and requests t
46. and encoder portions of the 7470A Anative of Hanoi Vietnam he attended the National Technical Center in Viet nam earning a BSME degree in 1974 I Chuong also received the BSME de Le gree from the University of Minnesota in 7 1979 and recently was awarded an HP rs Fellowship to complete his studies for P an MS degree He likes swimming and 2 music is married has one daughter and lives in Escondido California Richard M Kemplin Dick Kemplin has been with HP since 1954 and presently is a development engineer at HP s San Diego division His contributions have resulted in six patents related to mechanisms and two previous HP Journal articles Dick has an AA degree from John Muir College Pasadena California awarded in 1951 4 and served two years in the U S Army 2 gt _ Born in Glendale California he now X lives in Poway California Dick is mar ried has four children and is interested in art and building detailed scale mod els DECEMBER 1982 HEWLETT PACKARD JOURNAL 33 Copr 1949 1998 Hewlett Packard Co An Improved ac Power Switch Turning ac power on and off isn t always as simple as it seems Here s an ac power controller that is safe reliable long lived digitally controlled and interference free by Raymond A Robertson EARL 3v includes a device to apply ac power to the unit under test It may be a commercially available unit but more commonly is specially built It is normally a box con
47. as overcome was meeting the physical spacing re quirements There are three places that require isolation across the bias transformer from coil to contacts on each relay and from the gating circuit to the SCR The bias transformer is of a split bobbin construction A rib molded into the bobbin between the primary and the secondary of the transformer makes it easier to obtain the required physical separation The relay chosen has an eight millimeter separation from coil to contacts The SCR isolation could have been handled with an optoisolator This would have required either stealing the gate current from the load and not having zero current turn on as in the conventional solid state relays or putting in another iso lated supply to provide gate current Even though most optoisolators have sufficient breakdown voltage they do not provide very much physical separation between the emitter and the detector This can be a problem if there is a fault in either the emitter or the detector that causes the optoisolator to overheat This failure can result in destruc tion of the thin insulation between the circuits that are supposed to be isolated This failure mode would connect the ac line to the logic circuits A further problem with optoisolators is that a failure in the gating logic can cause the SCR to become stuck in the on position This would result in feeding half wave dc to the load This could dam age certain loads such as an ac motor
48. ause of excessive dv dt In either case the load never turns off Solid State Switch Protection Solid state relays can withstand a moderate amount of abuse from overcurrent They will typically withstand ten times rated current for about one cycle of the ac line Most 120Vac branch power lines can deliver in excess of 500 amperes into a short circuit Therefore it is difficult to select a fuse that will interrupt the line current fast enough to protect the switch in the event of a short circuit but that acts slowly enough to avoid the nuisance of blown fuses with normal inrush current Short circuit protection is im portant because many loads have fault conditions that re sult in abnormally high current A motor with a locked rotor will draw a high current as will a lamp whose filament has burned out and falls across the support leads It is inconve nient to have to replace the failed device and fuse but it is even more inconvenient to have to replace a destroyed switch as well Fig 2 Typical solid state relay block diagram DECEMBER 1982 HEWLETT PACKARD JOURNAL 35 Copr 1949 1998 Hewlett Packard Co Triacsrespond to overvoltage and to fast line spikes in the same manner they turn on and remain on for the remainder of the line cycle This is a problem when the triac is sup posed to be off It manifests itself as occasional half cycling This can bean inconvenience or a safety hazard depending on the nature of the load Not
49. ave enough word processing and report generation needs to justify using a computer Displaying 80 characters on the HP 85 s screen is imprac tical because the resulting small characters would be dif ficultto read The increasing concern that computer buyers have for ergonomics and human engineered computers dictates thatthe size of the CRT must be increased to display B0 characters per line How the CRT size is increased depends upon the product 6 HEWLETT PACKARD JOURNAL DECEMBER 1982 definition The HP 87XM is defined to be the top of the line for the Series 80 family It is designed with a built in 228 mm by 102 mm high resolution CRT The HP 86 is defined to be the nucleus of a low cost modular computer system A composite video output is provided to drive an external monitor This gives users some flexibility in pricing in that they can purchase the display that best fits their needs and budgets The modular concept also allows a user to select from various sizes and colors of display monitors A separate monitor also can be adjusted for optimum viewing distance and angle The HP 86 and HP 87XM CRT controller is designed to provide an 80 character line display in which a user can specify either 16 or 24 lines It has two graphics modes depending upon how much of the 16K bytes of CRT mem ory that a user wants to allocate to graphics NORMAL graphics gives a display of 400 by 240 dots and allows switching between the alpha and graph
50. d a 4 MHz Z80A microproce less than 1 7 watts Only about 130 cm of printed circuit board space was available in the standard Series 80 module not to mention a height con straint of 0 7 cm Just a few years ago a system like this would not have been possible but today s technology has provided the necessary pieces such as 64K RAMs The hardware is simple and straightforward in design The 82900A case consists of a standard size plug in module designed for the Series 80 computers Inside the plastic case is a single printed circuit board Fig 2 that has a Z80A microprocessor a 2K x 8 ROM eight 64K 1 dynamic RAMs a translator chip some miscellaneous LSTT gates and discrete devices The translator chip is a custom integrated circuit manufactured in HP s Corvallis Oregon facility It is very similar to the translator chips found in all the I O modules for the Series 80 computers and provides a convenient way to interface to the Series 80 bus The architecture of the system Fig 3 is straightforward The bidirectional data bus allows communications between the CPU ROM RAM and translator chip The address bus ofthe Z80A extends to the ROM and is multiplexed onto the RAM The translator chip resides at two of the I O addresses of the Z80A One Z80A port is the translator s addre sor that uses register and the other is the data register Any I O instruc tion turns the ROM off and enables the RAM The m
51. d a burn in carousel was ordered With this assembly line the above objectives were achieved Acknowledgments We are deeply indebted to Terry Siden for his guidance and encouragement Manufacturing team members were Gary McLeod Bob Ferrari John Powell Steve Sakumoto Wally Halli day John Morton Bill Gunther Carol Kinslow Gale Moreland and Walt Borra A great deal of thanks is owed to Ron Vanderlugt and his coworkers in the mold shop The San Diego Division s model shop under Richard Berktold and tool room under Norm Ashley came through every time The electronic tooling depart ment under Bud White and mechanical tooling department under Gary McLeod got us what we had to have to succeed Bob Porcelli characters per second Three interface options are available HP IB RS 232 C CCITT V 24 and HP IL Hewlett Packard Interface Loop See article on page 16 No periodic readjustments are required to maintain plot quality Maximum power consumption is only 25 watts Providing these features was a considerable challenge to the 7470A design team Low Cost Design Approach Low manufacturing cost high quality performance and reliability were the primary project objectives To achieve these objectives a technology had to be chosen Microgrip Hewlett Packard interface Bus HP s implementation of IEEE Standard 488 1978 DECEMBER 1982 HEWLETT PACKARD JOURNAL 13 Copr 1949 1998 Hewlett Packard Co drive tec
52. d servo system control Interpretation and execution of the HP GL plotter pro gramming language scaling character generation win dowing line type et cetera a I O control for the HP IB RS 232 C CCITT V 24 and HP IL interfaces Pen lift control The outside world communicates with the plotter via an HP IB control chip and buffers This integrated circuit handles the bus protocol and allows the microprocessor to be free from normal data transfer overhead T HE ELECTRONICS for the 7470A Graphics Plotter Hewlett Packard Graphics Language Hewiett Packard Interface Bus HP s implementation of IEEE Standard 488 1978 Hewlett Packard intertace Loop see article on page 16 5V 1A Linear 4e 5V Linear 12V Linear p 22V 14 Unregulated Motor Drive Supply Servo Two servos Fig 2 are used in the 7470A one to move the paper and the other to move the pen carriage The elec tronics for this consists of the microprocessor generating and sending digital move commands to the VLSI NMOS servo chips via the CMOS gate arrays The two gate arrays contain all the circuitry needed to support the VLSI circuits and driver sections of the electronics see box on page 25 The servo chips output pulse width modulated PWM and direction signals back to the gate arrays The gate arrays take these signals and generate the appropriate signals to control the switching motor drivers In addition the gate array
53. d wiring outside the rack permits easy assembly and simplifies later modifications Applications To ship more reliable equipment and keep warranty costs down many vendors have instituted a burn in policy The equipment is run from a few hours to several weeks so that early failures occur before the equipment is shipped How ever it is costly to tie up inventory and pay the electric bill for the burn in procedure To reduce these costs the same amount of stress can be induced by cycling the equipment The cycles can be timed on off cycles or a combination of time and temperature cycling The latter method produces more stress in a shorter period The 14570A an HP 85 Computer and a 6940B Multiprogrammer are ideally suited for this application For small installations a 14750A could be driven directly from a 16 bit GP IO interface installed in an HP 9915A Modular Computer When a computer is used to control ac power there are DECEMBER 1882 HEWLETT PACKARD JOURNAL 39 Copr 1949 1998 Hewlett Packard Co CAUTION GUB SERVICE wanas se caman Mt amp mcn masowa sometimes undesirable side effects often caused by EMI from the switch that is controlling the power The 14570A with its very quiet switching can cure many of these prob lems As an extra benefit the 14570A has an ac line filter that not only limits the peaks of any spikes that occur on the incoming line but also reduces the rise time of the portion o
54. dler pulley design changed from a simple plastic wheel on a steel dowel pin to a pulley pressed onto a Class 1 ball bearing This reduced Y axis friction by 15 The preload spring was added between the carriage and pen holder to reduce translational deadband and silence a noticeable servo buzz Extensive life and Class B environmental testing showed that the pen holder bushing clearances could be reduced to 0 025 mm well below the manufacturer s recommenda tions This helped reduce both rotational and translational deadband Finally to improve line quality further two deadband compensation algorithms were implemented in firmware One is used to correct for axis reversal deadband adding or subtracting this amount with each axis direction reversal The second a static friction compensation helps ensure that the X and Y axes begin to move simultaneously This is done at the start of each plot vector by preloading each servo error register with enough encoder counts to set up a condition of impending motion on each axis Each axis starts to move with the first count of the reference signal to that axis Without this compensation an axis would not break away until enough error counts built up to overcome axis static friction This delay could produce severe hooks at the start of low angle vectors when the rate of incoming reference counts to each axis can be very different Early prototypes showed that the pen holder inertia and high stiffness i
55. drawer positions as required in an HP 85 system The HP 87XM contains a built in HP IB interface It per forms all the functions done by the HP 82937A HP IB Inter face Module It has an output connector on the back panel along with switches to set its address and control mode Most HP 87XM systems are able to do all necessary I O mass storage and printing operations using only this inter face The HP 86 takes the built in interface concept one step further The most common use for the HP IB in the Series 80 family is to connect a computer to a disc drive and printer In the HP 86 a disc controller and printer interface are built in to eliminate the need for an HP IB interface The HP 86 uses the HP 9130A Flexible Disc Drive shown in Fig 2 This unit contains the same drive mechanism as the HP Copr 1949 1998 Hewlett Packard Co 82901M Series of 5 25 inch flexible disc drives The only difference is that the 9130A drive mechanism is individu ally packaged and receives all of its signals and power from the HP 86 mainframe The HP 86 user can purchase two of these units for less money and have the same storage capa bility as provided by an 82901M Flexible Disc Drive The savings comes from not having to purchase a separate power supply and controller The built in parallel printer interface provides a Centronics compatible connector that will work with the HP 82905B Option 242 Printer or many commercially available printers
56. e low cost objectives for the product After the technology was chosen other low cost design strategies had to be developed see article on page 23 They were as follows The plotter design was broken down into several modu lar assemblies such as the motor and encoder power supply electronics mechanics and packaging Cost ob jectives both materials and labor costs were set for each module Low cost manufacturing processes were selected wher ever possible such as 1 Custom integrated circuits HP manufactured NMOS servo chips 2 Semicustom integrated circuits to perform a number of logical functions 3 Two layer printed circuit board 4 Injection molded plastic parts 5 Linear logic power supply unregulated supply for motor drivers 6 Low parts count see Fig 2 Avoiding the use of conventional expensive manufac turing and design techniques as much as possible For example eliminating or reducing the use of 1 A cooling fan 2 Optical sensors and microswitches 3 Adjustments 4 Painting for mechanical parts 5 Silk screening 6 Multiple printed circuit boards and the associated number of expensive less reliable interboard con nectors Contracting with several specialized companies to man ufacture some standard parts and partial assemblies such as the selectively gold plated printed circuit board and the power module wire assembly These specialized vendors offer high quality parts and a
57. e more than 64K bytes of RAM but only 64K bytes are ena bled at any one time This and other techniques for memory expansion were considered but most were rejected because they placed too much of a burden on the system software to be efficient The method chosen for the EMC in the HP 86 and HP 87XM permits access to memory outside the di rectly addressable 64K range without burdening the operat ing system with excessive page swapping requirements The extended memory blends in with the Series 80 ar chitecture in a very direct manner Fig 5 The software specifies a 24 bit physical address and the EMC hardware manipulates it under software control The result is similar to adding a 24 bit stack pointer to the system except that the pointer is not kept inside the CPU but rather in each memory controller Each EMC can control either 32K 64K or 128K bytes of dynamic RAM Since the total memory space is broken into 32K byte banks this represents either one two or four memory banks per EMC A select code input into each EMC determines where the RAM it controls is located in the overall 24 bit memory address space Each EMC contains two 24 bit address registers that the CPU can read or write via a set of dedicated I O addresses To read an extended memory location the CPU must write its three address bytes low order first into one of the 24 bit address registers in each EMC The CPU then performs an indirect read operation to all EMCs b
58. ed to the main drive motors Since this voltage has to supply about 1 ampere rms it is less expensive if it does not have to be regulated This is possible because of the voltage sensing and servo gain adjust schemes described above To supply the negative voltages required for the I O and the servo chips charge pump circuits Fig 3 were chosen to run off the secondary of the transformer A half wave pump is used for the HP IB and HP IL interface versions of the 7470A The RS 232 C CCITT V 24 version requires a full wave pump The part sizes for operation at the low frequency limit of 47 Hz were acceptable so there was no need to consider operating at a higher frequency The extra parts needed for the charge pumps cost less than adding an extra transformer winding Copr 1949 1998 Hewlett Packard Co Custom IC Electronics for a Low Cost Plotter Itwas apparent early in the development of t was a need to integrate much of the electronics The digital portion most readily lends itself to integration in some form of custom IC The analog circuits on the other hand were designed with off the shelf parts but nevertheless benefited from the use of commercially available ICs In deciding which part of the digital electronics should be made into acustom IC we noticed that the microprocessor memory I O controller and buffers and the servo controllers were all in LSI large scale integration form already Our strategy then
59. ely conducting A typical trace is shown in Fig 1 n SCR SCR Relay Relay g Reverse Conducting Bouncing Closed k Biased gt g 1 6v 3 i 0 Time Fig 1 Typical voltage waveform across one of the 14570A s relays during turn on To check relay operate and bounce times it is only necessary to see if the voltage drop across the closed switch is above or below one volt When it is above one volt the SCR is conducting When it is below one volt the relay contacts are closed The one volt threshold can be raised to two volts to check whether the forward drop of the SCR is within limits A block diagram of the 6942A Multiprogrammer system designed to measure the timing and the voltage drops of the switch is shown in Fig 2 The 69771A Digital Input card has an ac In 38 HEWLETT PACKARD JOURNAL DECEMBER 1982 Testing the 14570A Fig 3 Photograph of the production test system analog comparator for each of its 16 inputs The reference voltage for these comparators is derived from a 697204 Digital to Analog Converter DAC card For instance if the DAC card is set to one volt the output of the digital input card will follow the position of the relay contacts With five microsecond response time the 69771A is able to follow very fast bounces The 69790A Memory card is connected to the input card so that up to 4095 sequential readings can be taken on the state of the 12 relays A 69735A Pulse Train Output card is
60. er the interpreter can step sequentially through the entire program regardless of its length or location Taking advantage of the architecture of the Series 80 processor some special features were added to the EMCs The processor has a number of multibyte commands that can operate on data one to eight bytes at a time Because multiple bytes are loaded and stored in the same sequence the EMC has to know the number of bytes being operated on to use these commands with the autoincrement autodecre ment features For example if the command is to au todecrement and store five bytes then the EMC has to dec rement its pointer by 5 before the bytes are stored This is done by allowing the EMC to monitor the instruction fetch line from the CPU Each EMC keeps track of the current instruction and therefore knows what number of bytes is being accessed This operation is transparent to the CPU and requires no additional processing time Display The HP 85 has a built in CRT that displays 16 lines of 32 characters each or a graphics display of 256 by 192 dots While this is adequate for most analysis and controller applications it can be very limiting when trying to do word processing or other business applications An 80 character line display is considered necessary to perform these applications properly Although the Series 80 com puters are not intended to be a family of business comput ers it is realized that many scientists and engineers h
61. es F July Harper Timothy V Dec Murrillo Richard D Mar Szeto Christina M Chambers Donald R July Hasebe Kunio Jan Muto Arthur S Nov Szeto Roger To Hoi Chen Devereaux C Oct Hay Robert A June Chiang Shang yi Aug Helmso Bennie E Mar Neil J Martin Nov Ta Chuong C Chiu Kuang Yi Aug Hodor Ken M Mar Nelson Loyd F May Takeda Teruo Chorak Steve May Holland Edward R Mar Neukermans Armand P Aug Takagi Susumu Coverstone Randy A Dec Holland Gary L July Taylor Wilhelm Cristal Edward G July Holmlund Gary W Feb Obara Michitaka Oct Thalmann James Crumly James D July Horning Robert J May Oh Soo Young Oct Toschi Elio A Hubby Laurence M Jr July Okada Susan Aug Tribolet David C Dalichow Rolf Feb Oldfield Danny J Apr Tsuruda Fumiro Davidson Andrew W Dec Ikemoto Jin ichi Oct Orr Jerry Feb Deane Pat Nov llic Dragan B Aug O Toole Michael M Aug Uhlrich Robert P DeGabriele Richard F Mar Ison Roger E May Mang Alert S Dejenfelt Anders T Oct Palermo David W May eS DR E Detro Michael C Nov Johnson Daniel E Dec Pecenco Irene V SU AMET Dierschow Carl M May Jones Victor C Feb Peetz Bruce E Nov Slee AREE Donald David K June Juve Ronald A June Petersen David M Dec Wilson john R Douglas J Guy Apr Peterson Val Feb Woo Arthur N Duffy William Sept Kamins Theodore I Aug Porcelli Robert J Des Weed mie Karin Michael J
62. etector plate spacing Solid mounting of optics holder to endbell assembly Careful attention was given here to make sure that the optics holder misaligned Also we tis gener asily dowr fear of damaging the code wheel fixturethat simulates an actual encoder to o ensure operation under worst Aspecially test the op case conditions Acknowledgments We would like to acknowledge Choung Ta for his efforts in designing and testing the optical holder and components code wheel and phase plate as well as his efforts on the printed circuit board layout which was inseparable from the product design of the overall encoder Also we would like to thank John Powell for his contribution in designing the encoder tester electronics Arthur K Wilson Art Wilson received an MS degree in mechanical engineering from the University of Arizona in 1970 He joined HP that same year as a de Sign engineer His most recent work has been the development of the 7470A s optical encoders He was born in Tucson Arizona is married and has one son Now living in San Diego California Art enjoys re storing antique automobiles his current project is a 1909 two cylin der Maxwell c Ui yr Af hib y a Daniel E Johnson Dan Johnson was born in Washington D C He attended Lafayette College Pennsylvania earning a BSEE degree in 1965 and the Polytechnic Institute of New York earning an MSEE degree in 1967
63. etion date One interesting application we have discovered allows the engineer to design a project on a microcomputer Dasoft M design automation software provides a library of ICs from which the engineer calls up pieces and specifies the signal names that correspond to the pins on the device The designer then specifies device placement on the schematic and printed circuit board The computer and its Wordstar is a trademark of Micropro Intemational Corporation SuperCale is a registered trademark of Sorcim Decimal Address Hexadecimal Address 65535 FFFF 60928 EE00 57344 E000 55296 D800 256 0100 o 0000 Fig 4 Memory map for 82900A system software take over and draw the schematic generate sorted network and material lists generate a wire wrap list that includes information on wire length autoroute 80 of the printed circuit board allow editing of the board lay out and generate artwork for the printed circuit board manufacturer Acknowledgments Jay Phillips was responsible for the boot ROM and BIOS software and was a key person in getting the 82900A done on time Ching Chao Liu did the binary executive Timothy V Harper Tim Harper joined HP in 1980 after earn ing a BSEE degree in computer design at Brigham Young University He has worked in both R amp D and production engineering on Series 80 plug ins such as the 82940A GPIO and 82929A pro 7 grammable ROM modules Tim was the project leader for the CP M m
64. f the spike that cannot be clipped This reduces the possi bility that these fast edges will be capacitively coupled into sensitive equipment connected to the 14570A The 14570A has three independent sections so it can be used in applications where distribution of three phase power is desired This also permits control of a mixture of 120V and 240V power Acknowledgments Special thanks to Yefim Kaushansky for help in finding suitable connectors and for designing the package that filled the sometimes contradictory requirements of meeting the required safety spacings being strong enough to meet environment specifications and being compact UNEAQUIPUITS Fig 4 Rear panel connectors were selected for safety and ease of use Raymond A Robertson Ray Robertson earned a BS degree in electrical engineering from Newark Col lege of Engineering in 1967 and an MS degree in computer science from New Jersey Institute of Technology in 1982 He joined HP in 1978and was a produc tion engineer before becoming project leader on the 14570A Before coming to HP he served three years in the U S Army and worked for a variety of elec tronics companies Ray was born in the Bronx New York is married lives in Rockaway Township New Jersey and has two sons He is a co inventoron two patents one on an electronic lock sys tem and the other on an automatic optical comparator and his work n the 14570A has resulted in a
65. g a simple integrated circuit mask change for the HP 85 RAM controller it still would have been unable to control more than a 64K address space A new dynamic RAM controller called the extended memory controller EMC was developed to access memory addresses beyond the 64K limitation of the HP 85 control ler The EMC serves two functions First it is an upgrade of the HP 85 RAM controller capable of handling either 16K or 64K dynamic RAMs the HP 85 controller can handle only 4K and 16K RAMs Second it provides for 24 bit addresses VisiCalc s a registered trademark of VisiCorp Additional UL 16K Plug in RAM 256 VO Addresses Fig 4 Memory map for HP 85 Computer Banks 2 18 HP 86 Banks 2 20 HP 87XM Each bank is 32K HP 86 Memory Limit Includes 32K system ROM HP 87XM Limit Includes 32K system ROM Fig 5 Memory map for HP 86 and HP 87XM Computers which makes it possible to address an effective memory space up to 16 megabytes considerably more than the cur rent physical memory limit including the 32K byte system ROM of 672K bytes for the HP 87 XM or 608K bytes for the HP 86 Since many microprocessors including the HP 85 s are designed to access only 64K bytes of information some special techniques are needed to expand memory beyond this limit Some systems accomplish this by page swapping in which the central processing unit CPU can enable or disable many different RAM pages These systems hav
66. hat the CP M system be loaded Once the system is loaded the boot code turns execution over to CP M and disappears A memory map of the 82900A RAM is shown in Fig 4 Applications The real power of the CP M operating system is the number of application programs available These applica tions run the complete range of microcomputer software In many cases a new piece of software is written for CP M before being coded for other systems The HP PLUS software program aids the user in finding and purchasing the HP disc formatted CP M software necessary to make your HP 86 or HP 87XM Computer intoa powerful new machine One of the most comforting things about CP M is that it offers every major language for computers So no matter what language you are used to programming in Pascal C COBOL FORTRAN all versions of BASIC Forth or assem bly all are available under the CP M umbrella Word processing software such as Wordstar and elec tronic spreadsheets such as SuperCalc will run under CP M Accounting software for a number of business appli cations is also available A novel application that could be quite useful is a PERT program evaluation and review technique chart gene tion program called Milestone With a friendly user in terface it asks you questions about how tasks are scheduled and arranged It then generates a PERT chart printout show ing when tasks should be performed on a project to meet its scheduled compl
67. he first time in the history of our lab it was not necessary to bulid a special box to control 1 power The 14570A is used to test the 145704 One section E 14570A is set for 115 volt operation and a second section is set for 230 volts Thus itis possible to select either 1150r 230 program control Fig 3 shows the 14570A test set drawn through a series resistor The resistor has a value that allows the relay to remain energized with less current than it needs to operate The lower current means that there are fewer watt seconds of energy stored in the coil The initial ener gizing current forced by the high operating voltage is well within the rated surge current for the coil Even with the increased operate current the reduced holding current brings the average power in the coil to less than the rated power In addition the circuit has a Zener protection diode across the drive transistor instead of the usual flyback diode across the relay coil The smaller amount of energy stored in the coil in conjunction with the higher flyback voltage for the coil greatly speeds up the release time With these measures it was possible to make the relay operate reliably in less than one fourth line cycle and release in less than one eighth line cycle Safety Considerations The 14570A is designed to meet the safety requirements of UL 1092 CSA 584A IEC 348 ANSI C39 5 VDE 0411 and the HP product safety manual One major safety problem that w
68. he translator chip was originally designed to interface with the 8049 microprocessor which has a multiplexed address data bus Because the Z80A does not have a multi plexed bus it was necessary to design the logic to do the multiplexing By using software to do the multiplexing we saved printed circuit board area Two Z80A instructions do the job One sends the address to the translator chip via the data bus and the second instruction sends or receives data toor from the translator chip It takes seven gates about one and one half LSTTL IC packages to implement this func tion T PACKARD JOURNAL 9 Copr 1949 1998 Hewlett Packard Co The RAM control logic is more complex than the other logic support area This logic generates four signals that control the RAM row address strobe RAS switch address multiplexers SMUX column address strobe CAS and read write WRITE All these signals are negative true A memory access to RAM consists of the following se quence The Z80A presents the desired address on the bus and signals a memory request MREQ The WRITE signal goes high or low depending on whether the access is a read ora write RAS becomes true and the RAMs latch in the eight row address bits The next edge of the clock switches the address multiplexers CAS becomes true one half clock cycle later and strobes the column address bits into the RAM After a finite delay the RAM has either read or wr
69. hnology invented in HP Laboratories in the 7580A Drafting Plotter and the 4700A Pag Cardiograph eliminates the problems associated conventional plotters by doing without heavy moving arms paper transport drums and belts Consequently be cause the microgrip drive system offers mechanical simplicity and low mass less power is required to drive the High impact plastic cover ac power module Two layer printed circuit board 13 button keyboard Optical encoder dc motor Pen axis tooted rubber belt drive Pinch wheel lever arms Paper foading lever 14 HEWLETT PACKARD JO BER pen and media This simple mechanism leads to a dynamic system that is easy to control aiding the design of a better servomechanism to give the plotter higher performance and output quality Although step motors would have fur nished a lower cost X Y drive dc motors were chosen to provide much higher plotting throughput An optical en coder built into each dc motor provides the necessary feed Metal ground plate stand Printed circuit board insulation One piece molded plastic chassis VN Penn solenoid Pen slider rods NE 1l POSEE and pen picks Pen drive belt tensioner Direct microgrip drive with grit wheels attached Copr 1949 1998 Hewlett Packard Co back to control the X Y movements This optical encoder was specially designed see article on page 26 to meet th
70. ics modes GRAPHALL mode allocates all the CRT memory to graphics and produces a display of 544 by 240 dots CRT graphics operations with the new CRT controller are faster than HP 85 graphics Graphics programs written on an HP 86 will run on an HP 87XM and vice versa but since the sizes and shapes of the CRT display are different they will produce differently shaped plots The HP 87XM provides an isotropic display with a 1 1 aspect ratio The physical distance between the dots is the same in the horizontal and vertical directions The monitor selected by the user for the HP 86 determines the aspect ratio but a SCALE statement is provided to allow the display to be adjusted to any monitor Internal Interfaces Built in interfaces are other features of the HP 86 and HP 87XM With the many Series 80 I O interface and expan sion modules available some HP 85 users find that the four expansion ports are quickly filled The problem could be worse for HP 86 and HP 87 XM users because they also have an assortment of RAM modules to choose from To help relieve this problem the new Series 80 computers are de signed with commonly used interfaces built in Not only does this free more expansion ports for specific user appli cations but the cost of a built in interface is less than that of a plug in module Additional ports are made available by including the mass storage and printer ROMs inside the HP 86 and HP 87 instead of having to use two ROM
71. ing off It is difficult to turn a relay on at zero voltage because of the several milliseconds of time uncertainty between the application of coil power and contact closure There are also several milliseconds of bounce when the relay contacts come together This bouncing causes rapid changes in load current which cause severe EMI and some Power c padecen o NU 2 ANNO Logic 36 HEWLETT PACKARD JOURNAL DECEMBER 1982 erosion of the relay contacts When the relay opens there is also a few milliseconds of time uncertainty between the removal of coil power and opening of the contacts This makes synchronization to the line cycle impractical When the contacts open there is less bounce than when the con tacts close but damage to the contacts is more severe and the EMI is worse than upon closing This seeming con tradiction exists because the air gap between the relay con tacts ionizes as they open The ionized air isa good conduc tor and might have as low as a 30 volt drop at six amperes The gap continues to conduct and carry almost the full load current until the line voltage nears the arc voltage While arcing therelay dissipates more than 100 watts of power for few milliseconds generates much EMI and suffers ero sion of itscontacts This results in two limitations on relays It is common to see relays rated at 240Vac but only 32Vdc because at 240Vdc the arc will not extinguish Also relays are usually re
72. iscellaneous logic can be divided into five func tional areas oscillator and clock driver circuitry ROM sel ct logic wait state generation Z80A translator com wpe 64K x1 RAMs RAM Multiplexers Fig 2 The electronics for the 82900A is mounted on a single printed circuit board munication control and RAM control logic simple Colpitts oscillator circuit is used to provide an 8 MHz sine wave This signal is divided by two to create the 4 MHz 50 duty cycle square wave clock necessary to run the single board computer The 2K x 8 boot ROM is switched into the address space whenever the module is reset from the mainframe a com mand is provided in the BIOS so that the Z80A can reset the system if necessary At power on the module is reset and the processor begins executing code from the boot ROM The system is organized so that all memory reads are ini tially from ROM and all memory writes are to RAM The boot ROM is switched off by executing any I O instruction that is INPUT port or OUTPUT port in the Z80A software and then all read or write operations are from or to RAM respectively Wait state generation is necessary on instruction fetches to allow the use of slower 200 ns RAM This causes a pro cessing speed loss of 10 to 15 depending on the software being executed This was considered a good tradeoff for the cost and power saved This circuitry is implemented with a spare flip flop and two gates T
73. itten the data and is ready for the next memory cycle From a hardware viewpoint here is what happens at power up The ROM is the selected memory device and the Z80A executes its instructions from ROM The Z80A does some housekeeping tasks RAM self test load boot code from ROM to RAM et cetera and then asks the mainframe to load the CP M system from the disc into the module s memory While the module is busy at power up the main frame HP 86 or HP 87XM performs its own self test and then loads the autostart program on the CP M disc which in turn loads and executes the binary program that services the T O requests of the 82900A The request to load the CP M operating system is granted and the standard CP M prompt A gt is displayed At this point CP M is operative and will execute any valid command CP M System CP M is an environment in which programs can be run and files can be accessed It provides a shell so that any standard CP M program can be run on any machine that can run the CP M operating system The operating system itself is not very complex but is an important link Without it much of the application software commercially available for small computers would not be executable on the Series 80 machines CP M is built of three basic parts The console command processor or CCP interfaces to the user and interprets the CP M commands the user gives it The basic disc operating system or BDOS handles file management operati
74. key assignments and the presence or absence of other I O buffers Thus each command must do a memory search to find the O buffer before the data it holds can be used The advantages of the I O buffer are that data is pro tected from inadvertent modification and that its use is totally transparent to the user Creating Bar Code The HP 41C uses a two level bar code meaning it is composed of two different bar widths Narrow bars repre sent 0 and wide bars represent 1 Spaces between bars serve only as delimiters and carry no information Two powerful user language programs are provided in the plotter module s manual to facilitate producing bar code The first is a collection of subroutines that labels and plots one row of program or data bar code The second PLOTBC is interactive and provides a quick and easy method for the novice user to produce bar code of programs and data An example of the output of this program appears in Fig 4 Developing a set of plotting parameters that would pro duce bar code of optimal geometry proved to be challeng ing Variations between pens and within the lifetime of a pen result in slightly different ink flow rates and line widths This difference is not significant for most plotting DECEMBER 1982 HEWLETT PACKARD JOURNAL 17 Copr 1949 1998 Hewlett Packard Co SINX X ROW 1 LINES 1 4 ROW 2 LINES 5 11 uses but it is enough to slightly alter the geometry of the bar code produced Thu
75. l positions Note that the carriage stalls in a unique position for each of the four cases A parking a pen in the stable B picking a Pen Stable P f b 32 HEWLETT PACKARD JOURNAL DECEMBER 1982 pen from the stable C no pens in both the stable and holder and D pens in both the stable and holder This is possible because the positions of the stable arms and pen holder arms depend on whether or not a pen is present Thus various mechanical stops present themselves to the carriage based on the relative positions of the stable and pen holder arms Fig 10 Sincea pen may exist in any or all of three locations there are eight possible ways pens could be configured upon power up An algorithm in the 7470A s electronics deter mines where all the pens are by simply using the various pen changer stall positions to deduce which of the eight possible pen configurations has been set up Chassis On the injection molded chassis are mounted all the mechanical parts for the operation of the pen carriage and paper mover servomechanisms and the pen lift system In addition it functions as an enclosure for the electronics and is cosmetically visible to the user see Fig 2 on page 14 As the main structural member of which many close tolerances are required high strength and processing re peatability are critical Maintaining a flat drawing surface David M Petersen David Petersen was born in Palo Alto California He joi
76. ld Roger D June Fitzgerald Kathleen A June Lewis John R July Roberts Richard J Armour John May Folchi Jack A Nov Linsky Mark S Mar Robertson James L Ashkenas David J Mar Fong Waymond Jan Liu E David Aug Robertson Raymond A Azmoon Majid Dec Foster Phillip G July Lowe Lawrence Apr Robison Billie J Frolik William R Dec Rogers Ronald G Balliew Pat May Fu Horng Sen Oct Ma Peter L Dec Rubinstein Jon Barber V Alan Sept Fullmer Douglas E Feb Maeda Kohichi Oct Beetem James E Mar Furukawa Michio Feb Marcoux Paul J Aug Sakayori Hiroshi Bennett Paul I Feb Martini Neal J Dec Sanders Steven N Biddle Stephen A Apr Garrettson Garrett A Aug Mason William R Jan Schwettmann Frederic N Bidwell John L May Gordon Philip June Matheson W Gordon Mar Schwiebert Erwin H Bird Steven C Nov Goris Andy May McDonald Bill Feb Shreve William R Brown Dave May Grinolds Hugh Aug McLucas James W May Sorden James L Brown William A Aug McTigue Mike Spencer Paul R Burgess Ken L May Haley James F Apr Meinert Karen L Sproviero Michael J Hall James A June Merchant Paul P Stewart Don D Camis Thomas June Hallissy Robert M May Meredith John Stewart J Marcus Campbell John W Sept Hansen Von L July Miller Robert M Stiglich Ronald F Campbell Monte R Sept Harding Russell J Sept Moll John L Stockton David Catlin Jam
77. le the 14570A can be interfaced to many different controllers using standard TTL voltage levels it was de signed as an accessory for HP s 6940B and 6942A Multipro grammers Thus it is most easily connected to a user s application as one of many functions under the supervision of the multiprogrammer Design Considerations Power relays have a typical lifetime of about 50 000 oper ations at full load In a test set that takes one minute to test each unit and operates for one 8 hour shift per day there will be over 100 000 relay operations a year Thus a typical relay will have a life of only about one half year A useful life of 10 years was one of the design goals for the 14570A Other goals were to design a safe and reliable rack mountable unit that would be easy to connect and compati ble with the 6940B and 6942A Multiprogrammers or any open collector digital source We were looking for an ac switch that generates no EMI has no losses and can withstand long term electrical abuse Fig 1 The HP 14570A AC Power Controller is designed for high reliability low interference au tomatic ac power switching in sys tems applications It has 12 out puts organized into three groups of four switches Each group has a single 115V or 230V ac power in put Twelve TTL compatible inputs control the 12 outputs Copr 1949 1998 Hewlett Packard Co Tominimize EMI generation the switch must turn on when the line v
78. mass pen carriage and electronic limit sensing provide an elegant simple and accurate plotting mechanism An Improved ac Power Switch by Raymond A Robertson A novel combination of solid state switches and mechanical relays provides reliable noise free control of ac power circuits In this Issue eme Our cover suggests a potential airfoil design application for two of this month s featured n products the HP 86 Personal Computer and the 7470A Plotter We re grateful to Pterodactyl Ltd of Watsonville California for their help with the photo Their original design calculations were done with an HP 35 Calculator mm The HP 86 and the HP 87XM two new members of HP s Series 80 personal computer family are the subjects of the article on page 3 These computers feature very large maxi mum memory capabilities up to 576K bytes for the HP 86 and up to 640K bytes for the HP 87XM That s quite a lot for a personal computer of this class and the article tells how they re able to do it Both computers can talk to a wide range of peripherals and instruments by means of built in and optional interfaces A plug in option described in this issue beginning on page 8 makes them compatible with the impressive variety of software packages based on the popular CP M operating system The 7470A Plotter is the latest and most economical of HP s plotters using the low mass low inertia microgrip paper drive technology first described in our October 1981 issue
79. mber 1981 issue of the Hewlett Packard Journal In this scheme two opposite edges of the plotting medium are each pinched between an aluminum oxide coated drive wheel and a pinch wheel As the drive wheels rotate the aluminum oxide particles form minute depressions in the surface of the plotting medium thus producing a drive track which can be followed on successive passes of the medium through the plotter Ideally each depression al ways realigns with the same aluminum oxide particle that created it Asa result of the tracking ability of the micro grip drive the 7470A achieves a repeatability of 0 1 mm with any given pen In plotters with a pen lift system paper flatness is a key design specification A plotter with poor paper flatness must use a higher pen lift to avoid inadvertent marking during pen up moves A large pen lift height increases the time required to raise and lower the pen thus impairing plotter throughput The 7470A uses a new approach to maintaining paper flatness tapered pinch rollers The tapered roller consists of a nylon hub beneath an elastometric polyurethane cover having a two degree taper Fig 4 When a sheet of paper is driven between the grit wheel and the conical pinch roller the paper tends to move laterally toward the large diameter end of the roller Thus if the pinch rollers are oriented with their large diameters toward the edge of the paper sheet Dynamic Contact Area Static Contact Area
80. n plotters such as the 7470A it is important for the plotter to know where all the pens are This prevents such undesirable events as trying to write without a pen selecting a nonexistent pen selecting the wrong pen and jamming two pens into each other When the 7470A is powered up a pen could exist in any or all of three loca tions the left stable the right stable and the pen holder It is a desirable feature if the plotter can identify where all the pens are without requiring the customer to power up the machine with a specific pen configuration In addition it is desirable if the plotter can detect a new pen configuration after initialization Earlier solutions to the pen sensing problem included the use of mechanical switches and opti cal detectors but these schemes entail added cost as well as reduced reliability A completely new scheme for sensing pens was de veloped for the 7470A This scheme uses Y axis servo posi tion error in combination with mechanical stops in the pen stables to assess where pens are and are not present The Y axis is driven by a dc motor in conjunction with an optical encoder which gives a position resolution of 0 025 mm Hence each count on the servo equals 0 025 mm of carriage motion The Y axis is said to stall or saturate when the servo position error reaches 48 counts This occurs when the pen carriage hits a mechanical stop such as a surface in the pen stable Fig 9 shows the various pen axis stal
81. n the pen s fiber tip resulted in a pen suspension natural frequency that was very sensitive to paper roughness Instead of tracking the paper the pen would skip over paper bumps leaving dashed ink lines This pen skipping was eliminated by getting the paper to track the nib and by reducing the Z axis natural frequency A 0 4 mm deep and 4 mm wide groove was molded into the platen under the line of pen tip travel The portion of the paper bridging the groove deflects under the pen s 20 gram writing force in effect placing a low stiffness leaf spring in series with the high stiffness pen fiber tip The pen suspension natural frequency is considerably lowered and more important over the deflection range of the paper the paper tracks the pen tip as it moves up and down The pen holder design required a plastic that would pro vide High material stiffness and strength to allow a low mass part Excellent processing and dimensional stability to allow tight tolerances to be held for pen change interfacing requirements Lubricity for low sliding friction A low wear rate for long service life Polycarbonate with 3096 glass fiber and 1596 Teflon was selected Its remarkable insensitivity to processing varia tions allowed holding a tolerance of 0 1 mm on an open section over a 40 mm length with reasonable ease It met the above goals well with high pressure velocity limits and dimensional stability allowing bushing to slider clea
82. nal memory built in interfaces and video display configuration Fig 1 The HP 86 Fig 2 is designed to provide the nucleus for the lowest cost Series 80 workstation system It has 64K bytes of internal RAM uses an external video monitor and has built in interfaces for two flexible disc drives and a printer The design provides a low cost computer that al lows the user to select peripheral components from a vari ety of sources The HP 87XM Fig 3 was designed as the premier per sonal computer of the Series 80 family It has 128K bytes of internal RAM and a built in 80 character by 24 line CRT display It uses a built in HP IB interface to communicate with external disc drives plotters and printers Both computers have four expansion ports which can be used to enhance their capabilities These ports are com pletely compatible with all Series 80 I O interfaces ROM and RAM modules for the HP 86 and HP 87XM are not interchangeable with the HP 85 s ROM and 16K RAM modules RAM modules are available in 32K 64K and 128K byte sizes Up tofour of these memory modules in any combination can be inserted into the ports of the HP 86 to increase its total RAM up to 576K bytes and in the HP 87XM to increase its total RAM to 640K bytes 1980 HEWLETT PACKARD introduced the HP 85 Software With a large number of HP 85s already in use it is desir able for new Series 80 computers to be compatible with existing HP 85 BASIC language
83. ned by the user to suit individual programming preferences User defined functions are changed to allow more than one parameter to be passed to the function Capabilities for handling one and two dimensional string arrays are also added Memory A major feature of the HP 86 and HP 87XM Computers is their ability to accommodate extremely large amounts of user memory This enables the user to manage larger pro grams and data files than previously possible on a personal computer With the development of memory intensive programs such as VisiCalc and linear programming software the need for more and more memory becomes apparent While only a couple of years ago the maximum 64K byte memory option for most 8 bit machines was considered an expen sive luxury now it is considered a minimum necessity This has been caused by the rapid drop in the cost of RAM devices coupled with the increased density with which RAM can be packed on logic boards The HP 85 has a maximum addressable memory space of 64K bytes see Fig 4 The first 32K bytes are reserved for the ROM operating system and external plug in ROMs The next 16K bytes are internal RAM A RAM module can be installed that occupies the next 15 75K bytes The last 256 memory addresses are used for I O devices and access to the CRT display memory One of the design objectives of the HP 86 and HP 87XM was to provide a minimum of 32K bytes of user RAM While this could have been done by makin
84. ned HP in 1978 and worked on the Y axis and pen lift of the 7470A He is a member of the ASME and has a BSME degree 1978 from California State Polytechnic University He is returning to school to earn an MSME degree at the University of California at Davis through HP s Fellow ship Program David is a cycling en thusiast and is working on a recumbent bicycle design His other interests in clude spending time with his family sail ing and beekeeping David is married has two sons and lives in Escondido California Fig 10 Diagram of interaction between the pen holder and the pen stable at the four stall posi tions a Parking Case A Note that the pen holder travels farther into the stable in parking than in picking b Picking Case B c No pen to no pen interference Case C d Pen to pen interfer ence Case D Note that because the tip of the pawl describes an arc about its pivot point the pen hold er travels slightly farther toward the stable if no pens are present than if two pens are present as in d V Copr 1949 1998 Hewlett Packard Co with less than 0 3 mm of bow over a distance of 215 mm is important to pen drop performance Because it serves asthe platen over which the paper moves the chassis needs to be conductive with no more than 20001Y 7 surface resistance to bleed off electrostatic charge After evaluating several plastic formulations a modified polyphenylene o
85. nical shape can be readily removed from the mold In addition by using a larger pinch force on one side the paper can be kept aligned against a reference edge located on the side with the higher pinch force This elimi nates the problem of lateral paper walking Early in the 7470A s development it became clear that the X axis was inherently a lower inertia mechanism than the Y axis However servo design is simplified if the two axes have equivalent inertias since this helps ensure that both axes have the same dynamic and steady state error be havior Inertia matching was achieved by incorporating a large diameter flywheel into one of the three parts used to couple the X axis motor to the drive wheel shaft Since the coupler part with the flywheel is injection molded the cost of inertia matching is very low Pen Changing Mechanism Multicolor and multipen plotting is clearly a desirable feature in a hard copy graphics device Conventional ap proaches to multicolor graphics include pen turrets off carriage pen arrays and on carriage pen arrays Pen turrets can be used to store a large number of pens and are well Fig 6 a Cross section of ta Net Force pered pinch roller showing defor AAA mation where it is pressed against S the paper b Magnified outline of static and dynamic contact area between the roller and the paper The asymmetry in the dynamic contact patch is caused by hys teresis in the deformed roller c Dyn
86. o concerts and playing guitar and is interested in audio equipment DECEMBER 1982 HEWLETT PACKARD JOURNAL 7 Copr 1949 1998 Hewlett Packard Co Module Brings CP M to HP s Latest Series 80 Computers This small computer system plugs into the HP 86 and HP 87XM Computers to allow them to use the wide variety of CP M compatible software available to the personal computer user by Timothy V Harper HE CP M OPERATING SYSTEM is the basis for some very well written software to help make your computer more friendly and useful To make it pos sible to use this software in the HP 86 and HP 87XM Com puters Hewlett Packard developed the HP 82900A CP M System Module The main focus of the 82900A design project was to cost effective solution to providing CP M capability and still have the power of the host computer available The 00A CP M tem Module is easy to use The module plugs into any available I O expansion slot in the back panel of an HP 86 or HP 87XM Computer Fig 1 a CP M disc is inserted into an attached drive unit and the system is turned on In a few seconds the second computer system provided by the 82900A for CP M operation is avail able for use develop a simple System Implementation This new computer module uses a Z80A as its master processor and the custom Series 80 processor as a slave I O processor The I O section BIOS of the CP M operating system is modified for
87. ode implements a software interface in two directions When communicating with BDOS it must rec ognize all the standard BIOS calls To handle the mainframe interface a protocol suitable for this application was in vented In most CP M systems the BIOS actually does the low level I O driving of peripherals In the 82900A BIOS sends commands to the mainframe where the low level drivers reside in the binary executive and the system ROMs of the HP 86 and HP 87XM The binary executive makes the mainframe a slave to the CP M system It interprets commands sent to it from the BIOS and causes the requests to be executed by the Series 80 peripherals Part of the problem in coding this binary pro gram is that the HP 86 87XM operating system is already a complex piece of software It is necessary to operate at a lower level than the available routines to achieve the de sired results A good example of this is the possibility of simultaneous interrupts from multiple devices Since it is not necessary to handle this situation under CP M no software for it is included in the binary executive This speeds up CP M operations In addition the binary execu tive insulates the CP M system from the Series 80 peripher als thus off loading some processing An example of this is key mapping To the normal Series 80 user an escape key is unnecessary but CP M applications do occasionally require an escape The binary executive maps the TR NORM key on the HP 86
88. odule and now is a project leader for new system electronics design He is a member of the IEEE and was born in Medford Oregon Tim is married has two chil dren and lives in Corvallis Oregon Besides being active in his church his greatest enjoyment is spending time with his family DECEMBER 1982 HEWLETT PACKARD JOURNAL 11 Copr 1949 1998 Hewlett Packard Co Development of a Low Cost High Quality Graphics Plotter A novel plotting technology and a design for low manufacturing cost have resulted in an inexpensive X Y plotter capable of fast high resolution graphics output by Majid Azmoon EWLETT PACKARD S San Diego Division has been supplying high quality graphics plotters to operate with HP computers and measurement systems since the development of the 9125A Plotter over a decade ago During this time several trends have developed The plot ter market is composed of several segments that are chang ing Within computer graphics the personal computer re volution is taking place More and more low cost personal computers are becoming available with capabilities previ ously reserved for much larger and more expensive sys tems Examples of low cost high performance HP personal computers are the HP 85 and more recently the HP 87XM and HP 86 As computation prices come down the need for low cost hard copy graphics increases At the same time many measurement devices are becom ing available that directl
89. oltage is zero and therefore when the load current is also zero It must turn off when the load current is zero Since the line voltage is not necessarily zero when the current is zero there must be provision for the voltage across the open switch to rise gradually to the line voltage Solid State Switches While it is possible to build a solid state switch that approaches the required low EMI most commercially available solid state switches do not perform as well as they could The main reason is that most solid state relays derive gate current for the switching element from the ac line The switch can not turn on until the line voltage has risen to a level sufficient to provide enough current A solution that is rarely implemented is to provide a separate supply for gate current The typical circuit for a solid state switch is given in Fig 2 It contains an isolation device a gate current limiting resistor and a solid state switching device In this case the isolator is an optocoupler A small relay is sometimes used in its place The switch in Fig 2 uses a triac triode ac semiconductor switch SCRs semiconductor controlled rectifiers are sometimes used instead and this results in a more rugged device but a somewhat more complicated cir cuit The circuit of Fig 2 has some problems The circuit is not synchronized to turn on at the zero crossing of the ac line Although this one does not some solid state relays do con tain a volt
90. only has to switch the voltage drop in the SCR circuit After the first half line cycle the gate current is removed from the SCR The turn off sequence is nearly the reverse of turn on When the external command is received to turn the channel off the logic signal is deglitched Just before the next posi tive line peak the SCR receives gate current and the relay coil is deenergized A few milliseconds later the relay contacts open and the SCR carries the line current until the SCR ceases to conduct at about zero current When the relay opens there is almost none of the destructive arcing that usually occurs when a relay opens because it only has to break the low forward voltage of the SCR The gate current is removed just after the line voltage goes to zero There were several reasons for choosing an SCR over a triac for the solid state switching element SCRs are gener ally more rugged they will withstand greater di dt and overcurrent Because SCRs are unidirectional they can be given gate current while the ac line is still negative and only a few milliamperes of parasitic remote base transistor cur rent will flow When the line forward biases it the SCR will start conducting immediately giving zero voltage turn on This eases the timing requirements on the solid state de vice To make the SCR even more immune to failure it has a 0 5 ohm resistor and a 1 microhenry inductor in series with it The resistor limits the peak current that
91. ons and allows application programs to access the wide range of system functions available by using simple subroutine calls like home disc read file et cetera The basic input output system or BIOS implements the low level I O functions such as get character and put character Of these three pieces only the BIOS needs to be rewritten for use on a new HP 86 or HP 87XM 10 HEWLETT PACKARD JOURNAL DECEMBER 1982 computer system This is one of the reasons CP M is such a popular system It is relatively simple to get it running on any computer with an 8080 Z80 or 8085 microprocessor Some other reasons for its popularity are the number of good application programs available for the operating sys tem CP M has been around a long time and a lot of pro grammers have had time to experiment with writing code that runs under it Because it is a software development environment it is naturally attractive to programmers CP M also has a large installed base and is available on many different manufacturers hardware This means a big market for anything that a programmer writes The Series 80 implementation of CP M is a standard no frills version of CP M That was the design goal and what is provided However the software provides for later addi tions to the system Currently things like graphics and HP IB function calls are not available because these would make the CP M for the Series 80 computers nonstandard Software The BIOS c
92. oodward An Input Output System for a 1 MIPS Computer W Gordon Matheson and J Marcus Stewart The Advanced Terminal Processor A New Terminal IO Controller for the HP 3000 James E Beetem GUEST A Signature Analysis Based Test System for ECL Logic Edward R Holland and James L Robertson Designing for Testability with GUEST Karen L Meinert Packaging the HP 3000 Series 64 Manmohan Kohli and Bennie E Helmso April 1982 An Integrated Test Set for Microwave Radio Link Baseband Analysis Richard J Roberts Design of a Precision Receiver for an Integrated Test Set J Guy Douglas and David Stockton Control and Display System for a Baseband Analyzer Law rence Lowe and Brian W Woodroffe A Combined Tracking and White Noise Generator John R Pottinger and Stephen A Biddle Wideband Fast Writing Oscilloscope Solves Difficult Measure ment Problems Danny J Oldfield and James F Haley May 1982 Advanced Multilingual Computer Systems for Measurement Automation and Computer Aided Engineering Applications John L Bidwell and David W Palermo Hardware Design for an Integrated Instrumentation Computer Sys tem Don D Stewart Robert J Horning Ken L Burgess Ronald G Rogers and James W McLucas VO Philosophy and Architecture for Instrumentation Control Loyd F Nelson Low Cost Printers for the 9826A and 9836A Computers Michael J Sproviero The 9826A 9836A Language Systems Kathryn Y Kwinn Robert M Hallissy and Roger E
93. phics Plotter uses dc motors for pen and paper positioning and optical encoders for position feedback To achieve good graphic output at a low cost the p system requires encoders with the following capabilities Two channel output for determining direction 500 line count per channel 500 r min maximum motor speed 25 degree phase accuracy per channel In addition to these requirements the 7470A project design team had two main objectives low cost and high reliability To achieve low cost we used A special motor with a built in endbell to house the encoder assembly Fig 1 This allows us to install the encoder directly lotter drive Drive Motor gt Endbell on the motor with no additional machining or related mounting costs An etched stainless steel code wheel and phase plate By using an etched code wheel with a closely toleranced bore we were able to use a low cost part and also eliminate the require ment of having to center it on the motor shaft Self stick adhesive bonding of the code wheel to the hub and pressfit of the code wheel hub assembly on the motor shaft jres eliminate the need for gluing fixtures and e and space required for this procedure We also These two f he code wheel hub assembly on the motor shaft to its y This elimi plate spacing correct location before adding th tics a nates having to adjust the code wheel to phas Encoder Printed
94. projects through the rear of the unit Each line input first passes through a line filter The first section of the filter is a common mode choke which at tenuates EMI generated by the 14570A as well as noise generated by the devices being controlled The second sec tion contains a normal mode filter and a pair of metal oxide varistors These components limit the magnitude of line spikes to less than 750 volts peak and reduce the rate of rise to less than 75 volts per microsecond This relatively clean power is then distributed to the devices being controlled Thefiltered power isalsorouted toa bias supply that is used to operate the timing circuits and to drive the relays and SCRs The 14570A turn on cycle begins when an external logic signal is received for a channel to turn on This signal goes through a digital delay circuit that filters out glitches short er than two milliseconds The logic circuit waits until one millisecond before the next positivetransition of the ac line The SCR is then given gate current and the relay coil is energized The SCR is reverse biased for a millisecond while the line is negative As soon as the line goes positive the SCR conducts The SCR gate current is derived from a separate bias supply and does not flow through the load A few milliseconds later the relay contacts close and the relay takes the burden of the line current from the SCR The SCR turns on and off every time the relay bounces so the relay
95. quential alpha and alpha append as well as commands to plot bar code Interactive plotting program This program prompts the user for the necessary data and then creates a complete plot It hasa wide range of options and is easily extended by user contributed subroutines The program provides data to three subroutines that initialize the plotting area plot the function or data and annotate the plot These three subroutines are also available for use in other user programs Plotting on the 7470A Like other HP plotters the 7470A s platen is divided into addressable units called absolute plotter units APUs On the 7470A there are 40 APUs to a millimeter To move the pen toa new location on the platen a plot command is sent to the plotter followed by X and Y coordinates in APUs However for the vast majority of plotting uses these default units are inappropriate Therefore it is useful to be able to superimpose another scale on top of the APUs Executing the plotter module s PINIT command maps a default scale called the graphic units GU scale onto the area specified by the plotter s lower left and upper right reference points P1 and P2 respectively On the 7470A the GU scale provides 0 to 100 units in the Y direction and 0 to 138 9 units in the X direction using the default settings of P1 and P2 In addition to scaling the entire platen it is convenient to be able to specify a portion of the platen as the active plotting a
96. r ances as low as 0 008 mm on a 6 4 mm diameter slider rod over an operating temperature range of 0 C to 65 C Unfor tunately it became apparent that 30 of the machines after life testing emitted a loud squeaking noise from the pen holder bushings Experiments varying bushing geometry and shaft surface roughness and employing lubricants failed to quiet the squeak The cost and clearance com promise solution uses screw machined bushings of Delrin A F which are snapped into place X Axis In the 7470A small diameter grit covered wheels move the plotting medium in the X direction obviating the need for many of the massive components typically found in the X axes of fixed media plotters Hence the paper moving Fig 4 Cross section of tapered pinch roller DECEMBER 1982 HEWLETT PACKARD JOURNAL 29 Copr 1949 1998 Hewlett Packard Co Edge Guide Ma Conical Pinch Roller Paper Fig 5 The plotting medium is kept flat by using tapered pinch rollers as shown The difference in forces F and Fz keeps the medium registered against the edge guide on the left approach yields an inherently low inertia X axis This in turn permits the use of smaller lower cost drive motors In addition a low inertia X axis makes the task of high per formance servo design somewhat easier and reduces power consumption The cornerstone of the 7470A s paper drive is the micro grip drive mechanism previously described in the Nove
97. rea and then superimpose a new scale on this area Then after a function has been plotted Fig 2 annotation can be done outside of this area so as not to obscure the data The plotter module s LOCATE statement allows the user to specify any desired subset of the plotter limits and the SCALE command maps any desired user units UU to the plotting area SINOO X os oo 05 1 Bom age I KN OG BO uS Fig 2 Example of a function plotted by an HP 41C 82184A Plotter Module 82160A HP IL Module and a 7470A Graphics Plotter Fig 3 Memory map of HP 41C system RAM VO Buffer To perform these functions the plotter module must keep all scale factors as well as P1 P2 and the endpoints of the area specified by LOCATE in memory Additional space is needed for status information and temporary storage of bar code geometry parameters The module stores all of this information in an I O buffer VO buffers are created in the HP 41C s memory above any key assignments see Fig 3 For the plotter module a 26 register I O buffer is needed The I O buffer has a header register which tells the operating system and any module scanning memory that an I O buffer has been found to which module the buffer belongs and how many regis ters there are in the buffer The drawback to using the 1 0 buffer structure is that its location in the HP 41C s memory is not fixed It may be shifted up or down depending on the number of
98. recorder Spectrum analysis SPICE parameters bipolar process Stability SMU Standards electrical interface Stimulus measurement unit SMU Storage digital waveform Storage oscilloscope Surface acoustic wave devices SWAMI process Sweeper stabilization microwave Switch ac power Synthesizer accuracy for microwave sources Synchronizer microwave source i Tape unit waveform recorder Terminal controller Thin film deposition plasma enhanced CVD Thin film stress Threshold voltage measurements Time base stability requirements waveform recorder Toner laser printer Tracking generator design Transmission line deflection plates Trench isolation process Triboelectric effect Trigger delay pre and post Trigger flag Trilayer resist process u User functions parameter testing v Variable persistence storage oscilloscope Vector processor IC chip Vector scan CRT display module Vernier electronic Vertical position circuit VLSI process technology w Waveform recorder Waveform storage digital White noise generator design White noise loading measurement White phase noise floor process Wideband power measurement Writing rate oscilloscope X ray lithography X ray masks X ray source Aug Aug Nov June Apr Apr Aug June Nov Sept Aug Oct Apr Apr Jan Sept Sept Aug Nov Sept Nov Apr Apr Nov Apr Apr Aug Aug Aug DECEMBER 1982 HEWLETT
99. s parameters set to produce suitable bar code with a new pen may later produce unreadable bar code as the pen begins to wear Plotting discrete bars would have required the pen to be dropped as many as 1584 times for a single page of bar code Pen wear caused by repeated nib impact against the paper is minimized by connecting all of the bars in a row at the top Fig 4 so that the pen is only lowered once at the start of a row of bar code This also speeds bar code production by eliminating the time delays associated with raising and lowering the pen Default parameters were chosen to produce the most con sistently readable bar code for the widest range of pen nib conditions and ink flow A 0 3 mm pen is assumed for these parameters and good results were obtained with both fiber tip and transparency pens Recognizing that users may choose to use different pens and that the pen nib width changes with use a command is provided to alter the bar code parameters BCSIZE allows users to specify in APUs any or all of the bar code parameters Creating bar code with the plotter module is a two step process Data is entered into either the X register or the ALPHA register of the HP 41C and then the appropriate bar code function is executed This creates the bit pattern of the desired bar code and places it in the ALPHA register A second command BC must then be executed to plot the bar code on the 7470A Interactive Plotting Program NEWPLOT is
100. s of that figure mat should be MAt DECEMBER 1982 HEWLETT PACKARD JOURNAL 15 Copr 1949 1998 Hewlett Packard Co Controlling a Graphics Plotter with a Handheld Programmable Calculator by Robert M Miller and Randy A Coverstone HE ADVENT OF THE HP IL Hewlett Packard Inter face Loop transformed the HP 41C from a pro grammable calculator into a true computer system with m s memory a variety of printers and a video dis play However one capability still lacking was some form of graphics output The HP 7470A Graphics Plotter with an HP IL interface and the HP 82184A Plotter Module Fig 1 was developed to satisfy that need As a computer the HP 41C possesses a powerful and flexible instruction set but is limited in speed and memory While it is possible to connect and control a plotter using only the control functions built into the interface module the resulting graphics programs would consume most of the available RAM and execution would be painfully slow The 82184A Plotter Module was designed to free the user from these limitations By providing a high level set of graphic commands in external ROM the HP 41C s system RAM is entirely available for the user s application programs Further all of the graphics primitives are written in machine language to minimize execution time The HP 41C with the 82184A Plotter Module the 82160A HP IL module and the 7470A Graphics Plotter make up a low cost
101. software For this reason a BASIC language interpreter and operating system is pro vided Because there are some differences in the internal Hewlett Packard Interface Bus HP s implementation of IEEE Standard 488 1978 representation of programs in these two new computers compared to the HP 85 s internal representation the HP 86 and HP 87XM havea built in translator to convert an HP 85 BASIC program to their internal representation after it is loaded The translated program can then berun or stored for future use as an HP 86 or HP 87XM program Keyboard Fig 1 System block diagram for the HP 86 and HP 87 Other than the differences in video output configuration built in inter faces and amount of internal memory the two computers use the same electronic system DECEMBER 1962 HEWLETT PACKARD JOURNAL 3 Copr 1949 1998 Hewlett Packard Co Binary programs written for the HP 85 will not run on the HP 86 or HP 87XM These programs do not know how to access the additional memory and do not know the loca tions of system subroutines in the HP 86 and HP 87XM ROMs Therefore HP 85 binary programs must be modified and recompiled before they can be used in the HP 86 or HP 87XM Most of the HP 85 software including its BASIC lan guage and on screen editing features is available in the HP 86 HP 87XM Several enhancements are added Al Fig 2 The HP 86 Computer is the a modular computer system It can
102. stricted to some slow rated switching speed such as 0 5 Hz This is necessary to keep the average power dissipated in the gap within the physical limits of the relay A typical medium power relay would last for less than a minute at its rated load if switched at 30 Hz The 14570A Solution From the above discussion it can be seen that relays make pretty good switches but physical limitations restrict what can be done to improve their performance On the other hand solid state switches offer a lot of promising capabil ity but typical circuit implementations and their lack of ruggedness make them less than ideal The 14570A AC Power Controller takes the best characteristics of each method to overcome the deficiencies of the other An SCR and a relay in parallel form the switching element The SCR makes and breaks the load current while the relay carries the load except for the first and the last few milliseconds of each on cycle Fig 3 is a block diagram of the 14570A The 14570A is an ac power distribution system There are three independent boards in each unit Each board has four ac power switching channels that share a common neutral line Thus there are 12 channels per box The ac power is fed Fig 3 14570A block diagram Only one of the 12 output channels is shown Each power input serves four output channels Copr 1949 1998 Hewlett Packard Co to each board through a connector that is mounted on the bottom of the board and
103. taining a power supply a relay and a relay driver Some of the fancier ones include inductors to enhance the life of the relay contacts and some sort of EMI electromagnetic interference filter ing While these devices do the job they generate EMI when turning on or off Many are special one of a kind designs and it is not only time consuming to design and fabricate a mounted box that has convenient input and output onnections but the finished product is sometimes less than ideal from the points of view of safety reliability and ctromagnetic compatibility The new HP Model 14570A AC Power Controller Fig 1 is a digitally controlled ac power line switch and distribu tion system that is designed to alleviate these problems It combines the best characteristics of relays and solid state switching devii an ac switching device that is safe and reliable s little EMI and has a relatively long life The 14570A is useful in applications that require any of the following capabilities Direct control of many medium power ac devices under program control e g process automation Control of ac devices where generation of EMI would cause sensitive equipment to malfunction Distribution of filtered ac power to sensitive instruments Typical applications include production test process control time or temperature cycled production burn in and other programmed control of small to medium power ac loads Whi
104. the SCR will see under fault conditions while the inductor limits di dt to a value that the SCR can safely withstand Since the SCR the series resistor and the series inductor conduct for only brief periods the impedance of the protection network can be relatively large to afford the necessary protection while the average power dissipated is very small in comparison to the peak Load Types Having chosen an SCR for the switching device there are some restrictions on the type of load to be switched and on the operate and release time of the relay The circuit de scribed works for any type of load at turn on Any resistive capacitive or inductive load has zero current at turn on if the line voltage is zero It is only after the load has been on that the line current starts to lead or lag the voltage At turn off for the SCR to conduct both the voltage and the current must be positive For a purely inductive load the earliest that this happens in a given cycle is just after the line has hit its peak and the current is just starting to go positive For a capacitive load this point is when the line is just starting to go positive and the load current is at its peak Inductive and capacitive currents are 180 degrees out of phase and the turn off circuit can not effectively work under both sets of conditions It was decided to have the turn off circuit optimized for inductive loads This includes motors solenoids and similiar types of lo
105. third patent application In his spare njoys numismatics rebuilding a vacation home home com puters stained glass lamp building and raising ducks time he HEWLETT PACKARD JOURNAL CHANGE OF ADDRESS Bulk Rate stage Paid ewiett Packai mpany 02001 AC a gzon ACECAOO JOHN IV APP A SOHN poco LAUR MD 20707 Copr 1949 1998 Hewlett Packard Co
106. tting axis is handled sepa rately to reduce mechanical complexity The pen carriage can select either of two pens stored in stalls located on opposite edges of the paper Y and Z Axes Patterned after the Y axis of the original Sweetheart mechanism developed by HP Laboratories the Y axis of the 7470A is driven by a dc motor and optical encoder assembly A drive pinion timing belt and idler pulley make up the power transmission loop the belt being attached to a slider block assembly which holds the pen The Z axis pen drop mechanism is a rotational spring mass and damper system To write the pen is allowed to fall and rest on the paper The pen is lifted as needed for nonplotting movement The design of the Y and Z axes uses the existing line of HP plotter pens whose delicate fiber tips can be easily crushed upon pen drop impact producing an undesirably wide ink line The inertia and impact velocity dictated by the pen size indicated that pen drop damping was required to avoid fiber tip damage The pen change system dictated a pen holder with complex detail and tight tolerances Servo per formance required keeping the pen drop mechanism and slider block masses low as well as minimizing Y axis fric tion and deadband The pen holder one of the two main parts of the slider block Fig 1 uses snap in bushings machined from Del tin A F and mounts directly on a stainless steel slider rod centerless ground to a precise diameter It
107. ttle bit of miscellaneous digital circuitry in the gate array implementations we began development of the array ICs First the circuits were designed using standard 74LS series ICs After breadboarding and testing was performed to check out the design a gate count was done to determine the array size required The resulting total gate count of 1200 precluded the use of one large array Instead two moderate sized arrays were chosen The circuits were then partitioned for a good fit in the following way The circuit functions for gate array A include the baud rate generator interrupt timer servo control and status ports memory decode Y axis motor drive control and Y axis servo gain adjust The circuit functions in gate array B include the pen solenoid pulse width modulator power supply voltage measurement circuit front panel input ports memory decode X axis motor drive control and X axis servo gain adjust During the development of the gate array ICs the LSTTL ver sion of the gate array circuitry was made into printed circuit boards These boards served as logic simulators for the ICs allowing the prototype 7470A instrument to operate while the ICs were in development These boards plugged directly into two 40 pin sockets on the instrument board via ribbon cables When the gate array ICs were ready the boards were replaced Peter Ma David M Ellement David Ellement received the BSEE de gree in 1976 from the University
108. uence the product design for improved manufactur ability This team developed the processes machines tooling and test fixtures for the fabrication assembly and testing of the 7470A The manufacturing team established a set of eleven objectives The primary objective coincided with that of the development team which was to keep the total manufacturing cost of the plotter below an established goal The plotter was not only to be low in cost but the volume was projected to be over two times that previously experienced by HP s San Diego Division This meant things had to be done differently on the production line The manufacturing team chose to try to provide a printed circuit board without gold a cost effective alternative to silk screening and an automated assembly line that would fit into 2700 square feet of factory space Two other major goals were to ensure a greater than 50 yield of good loaded printed circuit boards at the first pass on an HP 3060A Circuit Test System and better than 97 5 good printed circuit assemblies arriving at the assembly line The team was able to meet the total manufacturing cost target value within 10 and met all of the other objectives with the exception that gold is needed under the dome switches in the 7470A s keyboard area Parts Minimization The basic approach used throughout the product s develop ment to meet the manufacturing objectives was to reduce the number of parts to a minimum The product
109. use with HP Series 80 products A binary executive communicates with the CP M module to make the HP 86 or HP 87XM host processor behave as a slave I O processor The 82900A system has some special features most im plementations of CP M do not offer The HP 86 and HP 87XM can address a great deal of external RAM but CP M only recognizes the 64K of RAM addressable by the Z80A This implementation of CP M uses the mainframe RAM as a print buffer thus providing a pseudo print spooler For easy installation of CP M application software the 82900A offers subsets of two different terminal screen con trol protocols Both the HP 262X and Soroc 120 protocols are supported to the extent necessary under CP M Hardware Software Description A key to this project s success has been its short develop ment time From start of investigation to production was only nine months To adhere to sucha tight schedule it was important to keep the design simple and stay with the original design definition Fig 1 The HP Mode 82900A CP M System Module is a small stem containing a 2AM that plugs easily Copr 1949 1998 Hewlett Packard Co Clock Circuitry Miscellaneous Gate Logic HP Translator Ic ZB0A Microprocessor cono Cost was a concern too Not many people would be will ing to pay for example 1000 U S more for CP M capabil ity on their HP system Another big problem was designing hardware em with 64K of RAM an
110. ut only the EMC con trolling the desired memory location responds to the indi DECEMBER 1982 HEWLETT PACKARD JOURNAL 5 Copr 1949 1998 Hewlett Packard Co rect read by supplying the desired data byte to the CPU Writing is performed in the same manner using an indirect store command Whilethis may seem likea lot of overhead to read or write a single byte the EMC contains some features that greatly simplify the operations The 24 bit registers in the EMC are provided with some autoincrement and autodecrement fea tures similar to the stack pointer used in many micro processors Although it takes three bytes to access a single memory location the CPU can access the next higher or lower byte simply by using another indirect load This allows the CPU rapid access to an extremely large number of consecutive data bytes Since all EMCs load and modify their address registers together they always contain the same values The CPU can start using data from one EMC and continue reading past its assigned memory space into the address space of a second EMC Since the controllers are tracking one another the operation is passed between them without requiring any attention from the CPU This type of extended memory operation is especially suited to the Series 80 architecture The built in BASIC language interpreter considers the entire BASIC program to bea large data file By using the other 24 bit address register in each EMC as a program count
111. xide containing 1096 glass fiber 1096 car bon fiber for conductivity and 496 carbon black was specified for production At first this formulation was tried without the carbon black and it met the conductivity strength and platen bow requirements production parts have less than 0 15 mm of bow over 215 mm But dis couragingly the glass and carbon fibers were well displayed as light streaks in a sunburst pattern opposite the mold sprue gate located in the center of the platen After brainstorming the mold designers decided to move the sprue gate against a rear wall of the chassis which greatly improved the uniformity of appearance but not the color Carbon fiber loading in plastic means you can have any color as long as it is a shade of gray or black To achieve the uniform black color desired we added the 4 carbon black to the base composition which sufficiently hides the fiber streaks without making the part too brittle At this point in the plastic selection it was pointed out that the chassis function as an ac line voltage electronics enclosure required that the plastic composition be Under writers Laboratories U L flame rated V O This was at tempted by adding 20 of a flame retardant filler The Robert J Porcelli Bob Porcelli has been with HP since 1973 when he received the BS degree in mechanical engineering from the University of Texas at El Paso He is currently a manufacturing engineering supervisor at HP s
112. y use graphics plotters providing an attractive cost effective alternative to photographing CRT displays and plotting data by hand Many HP mea surement devices such as the 4145A Semiconductor Parameter Analyzer directly support plotter graphics and many more supply data toa controlling computer which in turn can drive a graphics plotter These two trends the availability of personal computers with big computer capabilities and intelligent instruments supporting plotter graphics have precipitated the need for a low cost plotter designed without sacrificing any of the high quality HP customers have come to expect To meet this need HP has developed the 7470A Graphics Plotter Fig 1 with the following feat res Accommodates either 812 by 11 inch ANSI A or 210 by 297 mm ISO A4 paper or HP s overhead transpar ency film Two built in pen stalls make two color plotting easy For additional colors the plotting can be halted from the 7470A 5s front panel or by program control new pens can be installed and the plotting resumed an inexpensive instru high quality output for mart instru ution mul and the us Copr 1949 1998 Hewlett Packard Co Manufacturing Team in the R amp D Lab A manufacturing team was formed early in the lab prototype phase of the 7470A Graphics Plotter project and became an integral part of the development effort Its primary responsibility was to infi
113. yet powerful graphics solution The Plotter Mod ule allows HP 41C users to produce bar and line charts as well as function and point plots on paper and transparen cies It also provides the capability to produce bar code of HP 41C programs and data on either the 7470A or the HP 82162A Thermal Printer The bar code can then be read back into the HP 41C via the HP 83153A Optical Wand Command Set The 82184A Plotter Module is an 8K word unit word length is 10 bits which adds 52 microcoded commands to the HP 41C s function set along with a sophisticated inter active plotting program written in RPN reverse Polish notation Many of the command names and functions are based on the graphic command sets of the HP 9845 Com puter and the HP 85 Personal Computer This allows users familiar with these products to master the plotter mod ule s commands quickly The module s functions are divided into three categories Plotting primitives These commands set up the plotter scale the plotting area to any convenient user units pro vide windowing move the pen from one location to another change pens raise and lower the pen draw and Fig 1 Modu he HP 82184A Plotter HP 82160A HP IL re easily inserted into two n Copr 1949 1998 Hewlett Packard Co label axes and digitize points Bar code primitives This category contains commands that create the bar code bit patterns for user programs and data numeric se
114. ying on belt tension to hold it in place Damper within Rigid Holder Slider Rod a Fig 2 Pen transport mechanism The slider block is sup ported and accurately guided by a centerless ground stainless steel rod The slider block is restrained from rotating about this rod by an aluminum lift bar whose rotation raises and lowers the pen Copr 1949 1998 Hewlett Packard Co Automatic Belt Tensioning Device Fig 3 Pen drive belt tensioner mechanism The pen lift is activated by a solenoid Held to the main chassis with one screw it lifts and drops the pen by rotating the aluminum extrusion It also retains the extrusion and plastic linkage parts Mounting the solenoid off the slider block greatly lowers slider block mass and reduces parts count and cost by not requiring a flexible trailing cable Off axis mounting also removes size and shape constraints allowing a low cost large mass produced solenoid to be used A compression molded silicone diaphragm pressed into the mounting detail on the carriage performs as a bellows damper see Fig 2 During a pen drop the solenoid rotates the aluminum extrusion so that the pen holder is free to fall As the pen holder descends it deflects the diaphragm This provides viscous damping by forcing air through a 5 mm long 0 4 mm diameter hole molded into the carriage During the initial development of the Y axis friction and deadband were found to be unacceptable The i

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