8080 Debug ICE User Manual Code Version 0.32 7/03
Contents
1. This command will verify compare two regions of memory and display any differences found Differences will be displayed as address in first region value in first region value in second region Format V start end dest Parameters are d16 All bytes from start to end inclusive will be compared W Write memory out as Intel Hex file Used to save target system EPROM images etc in Intel Hex format A 16 bit offset must be entered This offset will be added to the addresses in the Hex file before storing the file data in memory This may be useful if the code is located at an address other than 0 but you want the Intel Hex file addresses to start at 0 for loading into an EPROM programmer for instance Offset addition will wrap at 64K so OxFO000 0x1000 0x0000 If you don t want any offset just enter 0 Format W start end offset Parameters are d16 All bytes from start to end inclusive will be written Start must be a lower address than end X Examine and edit the contents of the 8080 s registers Used to display or change 8080 register contents Valid register selection arguments are F A B D H S P HL BC and DE must be edited as a 16 bit pair Format X regsel If no register selection argument is enterred the complete register set will be displayed Example OK gt X Lista A 00 BC 1234 DE F74C HL 5542 S FFFO P 824D MOV A L Chapter 7 Cabling Information Two ways to connect ribbon cable depending2. starting address Starting address entered as 1 4 hex digits If no starting address is entered current PC value is used I Input from I O port Input 8 bit data from selected 8080 I O port and display it Format I address 8 bit I O address entered as 1 2 hex digits L List memory Lists disassembles memory contents from start address to end as 8080 instructions Format L start end Addresses entered as 1 4 hex digits Both parameters are optional If no end address is entered 19 instructions will be displayed If no start address is entered display begins at the next address after the end of the last D or L command This is the saved memory address So entering just L will start displaying from the end of the previous L command Example OK gt 1 0 25 0000 F3 DI 0001 31 FO 80 LXI SP 80FO 0004 21 00 00 LXI H 0000 0007 01 00 00 LXI B 0000 000A 1E 1A MVI E 1A 000C 7E MOV A M 000D 81 ADD C 000E 4F MOV C A OOOF 78 MOV A B 0010 cE 00 ACI 00 0012 47 MOV B A 0013 23 INX H 0014 1D DCR E 0015 c2 Oc 00 JNZ 000C 0018 D3 00 OUT 00 001A 00 NOP 001B c3 00 00 JMP 0000 001E cc Oc 00 cz 000c 0021 c4 1a 00 CNZ 001A 0024 00 NOP 0025 00 NOP M Move memory block Moves a block of memory data from one area of memory to another The destination area must be writeable for the command to work but no attempt is made to confirm that the write actually succeeded Format M start end dest The block of
3. WRb signals from reaching the target system In Quit mode these two signals are forced to their inactive state in the target system to insure that the target system is not using the data bus This is necessary as the data bus is used for PIC to 8080 communication in this mode In Go mode the PIC chip starts up the 8080 and lets it run In this mode the ICE operates just like a normal 8080 chip In Quit mode the 8080 has been paused and can be used to implement the commands that give the ICE its power All communication with the target system s memory takes place through the 8080 To read data from a memory location the PIC arranges for the 8080 to read from that location and then hand the data to the PIC If the 8080 is halted it is not fetching op codes and cannot be controlled by the PIC chip This condition is detected and a message is displayed The system must be reset to restore normal operation The 74HC4049 chip converts the 0 12V PHI 1 and PHI 2 8080 clock signals into 0 5V signals that can be fed into the CPLD Chapter 9 Watchdog Timer 8080 Reset Issue Some 8080 based designs may have a circuit called a watchdog timer When code is executing normally the 8080 writes to or reads from a particular I O or memory address maybe a few times each second This action resets the timer and maintains normal operation If the CPU crashes it stops resetting the timer As a result the timer reaches a preset count which causes the RES
4. data between start and end inclusive is copied to a new area of memory starting at dest MD Memory detect Reads and writes 16 bytes at start of all 64 1K pages of target memory and tries to detect read only memory and RAM If data always reads the same despite writing several patterns we assume its read only memory If data always matches what we wrote we assume it s RAM Data in each 1K page is compared with data in lower 1K pages to detect stuck or unconnected upper address bits or the same memory appearing several times in the memory space Page number displayed is lowest 1K page in target memory that contains the same data as this one If no memory repeats then each page will display its own page number Note that if the bus always floats to the same value or is terminated to a logic one level when floating the data will always read the same so it will be detected as read only memory Note Executing this command will write to the first 16 bytes of every page so memory contents will be changed Format MD Example 0000000000000000111111111111111122222222222222223333333333333333 0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF RRRRRRRR RRRRRRRR RRRRRRRR 00000000 00000000 WWWWWwWww 00000000 00000000 33333333 01234567 01234567 89ABCDEF Above display shows 8K Read only memory located in first eight 1K pages and the same memory appears at 32K as well An 8K RAM appears only in the top 8K pages 00000000000
5. not used in this mode In Quit mode the 8080 is paused and can be used to implement the full set of commands such as displaying or disassembling memory computing checksums writing to I O ports etc The Trace and Untrace commands can be used in Quit mode to execute code but not at full speed Since the Trace mode displays all of the registers after each instruction its speed is affected by the baud rate being used This command is always slower than Untrace The Untrace command does not display anything after each instruction but it does grab the current PC value from the 8080 to check against breakpoints and printpoints This takes some time With the 8080 clocked at 2 MHz Untrace executes roughly 1600 instructions second This is not fast enough to keep up with data coming off of a floppy disk so don t try to boot from a floppy in untrace mode Interrupts The ICE can recognize interrupts in Go mode but not in Quit mode In Go mode the user can enable or disable interrupts reaching the CPU In Quit mode no interrupts can reach the CPU Hold Requests The ICE can recognize Hold requests in Go mode but not in Quit mode In Go mode the user can enable or disable Hold requests reaching the CPU In Quit mode no Hold requests can reach the CPU Reset The PIC MCU uses the same reset signal as the 8080 so it comes up in a known state whenever the 8080 gets reset Interrupts are enabled or will be at least when Go mode is en
6. on how you want ribbon cable to face on target system Right Angle Header Normal Connection r ICE C t DIP pl ket Components on this side A plugsacke 21 20 ae vA Ribbon Cable oo cae Red Stripe DIP Plug 1 raised pin numbers Pin 1 of 280 connects here are correct Pin 1 of ZRO connects here Reverse Connection ICE 1 40 0 Please be careful when using this connection as the pin numbers on the DIP plug and the red stripe will be Ribbon Cable misleading Plugging the ICE in incorrectly will probably damage it 20 21 ae N Red Stripe DIP Plug Right Angle Header raised pin NEA numbers Components on this side are incorrect Chapter 8 How does it work The ICE consists of a 2 MHz 8080 CPU a 74HC4049 level shifter chip a CPLD custom logic chip an RS 232 level translator charge pump chip and a PIC microcontroller The PIC chip communicates with a terminal through the RS 232 chip and controls the 8080 It is capable of reading 8080 register values loading the 8080 s registers single stepping the 8080 through code starting the 8080 running at full speed and stopping the 8080 The CPLD chip contains logic to allow the PIC to control the 8080 and also to inhibit the hold request and interrupt signals from reaching the 8080 It can also prevent the 8080 s DBIN and
7. or untrace command when reached and enabled during either of these commands They are compared to the current PC after each instruction is executed Breakpoints only work in Quit mode Current breakpoint status can be displayed with the ST command Format BP n d16 nis 1 2 or 3 d16 is a 16 bit address Example OK gt ST gt OABC 00 D gt 0246 00 D gt 0369 00 D IH OK gt BP 1 123 OK gt BP 2 654 OK gt BP 3 982 OK gt ST gt 0123 00 D gt 0654 00 D gt 0982 00 D IH BPC Set breakpoint pass count Sets the pass count for one of the three breakpoint addresses which are used by the trace and untrace commands Count 0 and count 1 will produce the same result Setting the count to 3 will cause a trace to stop on the third time that breakpoint matches the current PC If it is enabled If the pass count does not reach zero while a trace or untrace command is executing its value is preserved and can be examined with the ST command to see how many times that breakpoint was hit So if the pass count was set to 10 at the start of the command and is 7 after the trace or untrace stops that address was hit 3 times Format BPC n d8 nis 1 2 or 3 d8 is an 8 bit count Example OK gt ST gt 0123 00 gt 0654 00 gt 0982 00 IH ovg OK gt BPC 1 33 OK gt BPC 2 66 OK gt BPC 3 99 OK gt ST gt 0123 33 gt 0654 66 gt 09
8. 00000111111111111111122222222222222223333333333333333 0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR WWWWWWWWWWWWWWW WWW WWW WWW WWW WWW WWWWWWWWWWWWWwWWwwwwwwwwwOOOOOOO0O 0000000000000000111111111111111122222222222222223333333333333333 0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF Above display shows 8K Read only memory located in top eight 1K pages The rest of the address space is filled with RAM that is fully decoded Does not repeat MT Memory test Performs a destructive test of memory by writing a rotating pattern of first a single bit then a single 0 bit and the rest ones to each memory location in the indicated range After the pattern is written to the entire area all locations are checked to see if the value read matches what was written Any mismatches are displayed as address value written value read The entire memory range is written and read 16 times so any particular address may appear in the error list up to 16 times if it fails for all data values Format MT start end O Output to I O port Write 8 bit data entered to selected 8080 I O port Format O port d8 8 bit I O port number address entered as 1 2 hex digits P Put write data into a target system memory location Write 8 bit data entered to selected 8080 memory location This command writes to a single memory location and is useful for creating
9. 8080 Debug ICE User Manual Code Version 0 32 7 03 2011 Chapter 1 Introduction Background The Intel 8080 microprocessor was popular in the mid to late 1970 s and was the processor used in the first examples of what would later be called S 100 computer systems Once the Z80 was introduced the 8080 became less attractive as it required three supply voltages a two phase clock and an external status latch The Z80 worked off a single 5V supply required a single clock input and brought out the necessary status signals with no latch required This simplified the design and reduced cost After designing a simple PIC based Z80 ICE I decided to work on an 8080 version as well Hopefully it will be useful for maintaining and troubleshooting early 8080 based computer designs Like the Z80 ICE it can display memory write to I O ports etc Before I started the Z80 design I became aware of a product developed in the early 80 s by Nicolet Paratronics called the Z80 NICE It offered a lot more capabilities than I had planned to implement with only a small increase in component cost Using the capabilities of this device as a reference I designed the Z80 ICE which is very similar to the 8080 one I added some new capabilities as well which I hope will prove useful Many thanks to Jeff Jonas for the generous loan of his NICE unit so I could become familiar with it Chapter 2 Setup The 8080 ICE was designed to be used with either a terminal or a ter
10. 82 99 IH ovg EBP Enable breakpoint s Enables one of the three breakpoints which are used by the trace and untrace commands If no parameter is entered all three breakpoints will be enabled Format EBP n nis 1 2 or 3 DBP Disable breakpoint s Disables one of the three breakpoints which are used by the trace and untrace commands If no parameter is entered all three breakpoints will be disabled Format DBP n nis 1 2 or 3 Example OK gt ST gt 0123 33 gt 0654 66 gt 0982 99 IH ovg OK gt EBP OK gt ST gt 0123 33 E gt 0654 66 E gt 0982 99 E IH OK gt DBP 3 OK gt ST gt 0123 33 E gt 0654 66 E gt 0982 99 D IH EPP Enable printpoint s Enables one of the three printpoints which are used by the trace and untrace commands If no parameter is entered all three printpoints will be enabled Printpoints cause the current 8080 register values to be displayed when reached and enabled during an untrace command They are compared to the current PC after each instruction is executed Note that printpoints and breakpoints share the same three address values so a particular address can be enabled as a breakpoint a printpoint or both Breakpoint pass count values don t affect printpoint operation Format EPP n nis 1 2 or 3 DPP Disable printpoint s Disables one of the three printpoints which are used by the tra
11. 9 0000 C3 Fl A5 26 72 89 CE 27 F3 06 82 01 CD 00 77 BC This text do 0010 3c 1F 5A 62 CE 98 CE 27 F3 06 82 01 CD 00 77 BC es not go with t OK gt D 0020 C3 F1 A5 26 72 89 CE 27 F3 06 82 01 CD 00 77 BC he data on the 1 0030 3C 1F 5A 62 CE 98 CE 27 F3 06 82 01 CD 00 77 BC eft eee 0040 C3 Fl A5 26 72 89 CE 27 F3 06 82 01 CD 00 77 BC I once shot an 0050 3C 1F 5A 62 CE 98 CE 27 F3 06 82 01 CD 00 77 BC elephant in my p 0060 C3 Fl A5 26 72 89 CE 27 F3 06 82 01 CD 00 77 BC ajamas what he 0070 3C 1F 5A 62 CE 98 CE 27 F3 06 82 01 CD 00 77 BC was doing in my 0080 C3 F1 A5 26 72 89 CE 27 F3 06 82 01 CD 00 77 BC pajamas I 11 nev 0090 3c 1F 5A 62 CE 98 CE 27 F3 06 82 01 CD 00 77 BC er know E Examine a single memory location Read 8 bit data from selected 8080 memory address and display it This command reads from a single 8080 memory location unlike the D command and is useful for creating a repeated memory read operation with the Z and RL commands so that target system signals can be examined with a non storage oscilloscope Format E address 16 bit memory address entered as 1 4 hex digits F Fill memory Fills memory from start address to end with the value given Format F start end value Addresses entered as 1 4 hex digits Value is 1 2 hex digits Same value is written to every location No attempt is made to verify that the write succeeded G Go Go Start 8080 CPU executing at full speed Format G
12. ET input to the 8080 to go high resetting the CPU and restoring normal operation of the system If an ICE is used since the 8080 is paused a lot of the time the watchdog timer will not get reset and will keep resetting the 8080 and the PIC chip perhaps five times second or faster The ICE can t work if it keeps getting reset There are two ways that the ICE can be used in systems with a watchdog timer 1 Disable the watchdog timer Some boards may have a jumper on the main board that can be used for this purpose You may need to solder across two pads temporarily to disable the timer Other systems may have a different way to disable the timer or no way at all 2 Modify the ICE to supply its own RESET signal to the 8080 and the PIC chip If you do this you ll need to cycle power to the ICE to reset it since any target system reset switch will no longer function Provision has been made on the pc board for an optional reset circuit To use this circuit open jumper JP1 which is normally shorted and install C17 R1 and D1 These components are normally not installed The values shown on the schematic for R1 and C17 have not been tested and may need to be adjusted for reliable operation D1 prevents C17 from discharging into the CPLD and 8080 when power is removed 3 Chapter 10 Code with a Halt Instruction The PIC controls the 8080 by feeding it opcodes When the 8080 executes a Halt instruction it stops fetching opcodes and wai
13. a repeated memory write operation with the Z and RL commands so that target system signals can be examined with a non storage oscilloscope Format P address d8 16 bit memory address entered as 1 4 hex digits R Read Intel Hex file into memory Used to load target system memory with test programs etc saved in Intel Hex format An optional 16 bit offset may be entered This offset will be added to the addresses in the Hex file before storing the file data in memory This is useful if the code being loaded is relocatable If no offset is entered an offset of 0 is used No offset The R command can process data and store it in the target system s memory at up to 19 2 K baud if the target system is running at 1 MHz or higher If a slower 8080 clock is used higher baud rates can cause a data overrun condition which will cause an error message to be displayed Using hardware handshake won t fix this as the PC takes too long to react to CTS going inactive In this case simply switch to a slower baud rate Format R d16 S Substitute into memory Used to load hex data values into system memory No attempt is made to determine if write to memory was successful so you can substitute into EPROM but it won t accomplish much Format S d16 To advance to next address without changing contents hit CR To back up to previous address hit a dash To exit substitute memory mode hit a period SR Soft reset Caus
14. ce and untrace commands If no parameter is entered all three printpoints will be disabled Format DPP n nis 1 2 or 3 Example OK gt EPP OK gt ST gt 0123 33 E gt 0654 66 D gt 0982 99 E uuv OK gt DPP 2 OK gt DPP 3 OK gt ST gt 0123 33 E P gt 0654 66 gt 0982 99 IH moO EI Enable interrupts Enables interrupts to reach the 8080 when in Go mode If this command is entered while the CPU is in Go mode interrupts will be enabled immediately An T appears on the last line of the status display if interrupts are currently enabled Interrupts are always disabled in Quit mode even if an I is displayed Format DI EI Disable interrupts Prevents interrupts from reaching the 8080 when in Go mode If this command is entered while the CPU is in Go mode interrupts will be disabled immediately Format EI Example OK IH OK OK H OK OK IH OK gt 0123 33 gt 0654 66 gt 0982 99 gt 0123 33 gt 0654 66 gt 0982 99 gt 0123 33 gt 0654 66 gt 0982 99 gt gt mom uvu uvu uvu EH Enable hold requests Enables hold requests to reach the 8080 when in Go mode If this command is entered while the CPU is in Go mode hold requests will be enabled immediately An H appears on the last line of the status display if hold requests are currently enabled Hold requests are always disabl
15. cepted or caused an error when it was executed In either case the ICE is ready for a new command to be entered Some commands may take a long time to execute and you may decide to abort the command The following commands may be either paused using Ctl S then resumed using Ctl S or Ctl Q or stopped by using Ctl C D Display memory L List memory V Verify compare memory T Trace U Untrace It is possible to put more than one command on the same command line In this case use a semicolon instead of carriage return to signal the end of a command Using the repeat line RL command it is possible to repeat a sequence of commands in a loop Delay can be inserted between commands with the Z command For example the command O 80 A5 Z 10 RL lt CR gt will write A5 to I O address 80 then delay for 16 0x10 mSec and repeat To break out of the loop press Ctl C The following commands always end command line processing and will prevent looping if used in a command line repeat loop G L Q R S T U W X Chapter 4 Overview of Operation The ICE has two modes of operation Go mode and Quit mode In Go mode the ICE executes 8080 instructions at full speed but not all of the commands are available Basically commands that don t require participation by the 8080 can be executed in this mode such as enabling or disabling interrupts or hold requests to the 8080 Breakpoints can be changed in Go mode since they are
16. ed in Quit mode even if an H is displayed Format DH EH Disables hold requests from reaching 8080 when in Go mode If this command is entered while the CPU is in Go mode hold requests will be disabled immediately Format DH Example OK IH OK OK I OK OK IH OK gt 0123 33 gt 0654 66 gt 0982 99 gt 0123 33 gt 0654 66 gt 0982 99 gt 0123 33 gt 0654 66 gt 0982 99 gt gt Disable hold requests uvu uvu vuy EA Enable Autorun Enables Autorun after power up or reset This setting is saved in EEPROM and will be maintained even when power is removed Enabling Autorun causes the 8080 to immediately start executing code from address 0 at power up The ICE is in Go mode at this point Interrupts and hold requests are enabled The current Autorun setting is part of the status display Format EA DA Disable Autorun Disables Autorun after power up or reset This setting is saved in EEPROM and will be maintained even when power is removed Disabling Autorun causes the ICE to enter Quit mode at power up until a G command is executed Format DA Example OK gt EA OK gt ST gt 0000 00 gt 0000 00 gt 0000 00 IHA ovg OK gt DA OK gt ST gt 0000 00 gt 0000 00 gt 0000 00 IH 000 H Hex calculator Computes hexadecimal sum and difference If values entered are A and B in that ord
17. er command displays A B A B Results are limited to 16 bits and will wrap above OxFFFF Format H d16 d16 Values entered as 1 4 hex digits Example OK gt H 10A5 674C 77F1 A959 OK gt H FFFE 0002 0000 FFFC OK gt H 2000 1000 3000 1000 CF Clock frequency Measure the frequency of the 8080 clock Value displayed can have up to 1 part in 256 or about 0 4 error Minimum displayable clock rate is 19 KHz Format CF Example OK gt CF 8080 clock frequency is 1 993 MHz Q Quit Quit stop 8080 and enter Quit mode Format Q Example Pe aan A 00 BC 1234 DE F74C HL 5542 S FFFO P 824D MOV A L RL Repeat Line This command may be used to repeat a command or group of commands on a single command line This could be used together with the sleep command to create a repetitive write to the same memory location for instance so that an oscilloscope can be used to observe timing and signal behavior To break out of the loop press Ctl C Example OK gt P 8000 A5 Z 9 RL Above command line will write 0xA5 to address 0x8000 then it will delay for 9 mSec then repeat ST Status Display breakpoint printpoint and hardware status The first three lines of the status display are devoted to breakpoint printpoint information The first value is the address which will be compared to the PC The second value is the breakpoint pass count The third value is either a D or E which indicates whe
18. es the ICE to reset all of the 8080 s registers to zeroes Format SR T Trace This command may be used to step through target system code one instruction at a time The 8080 s internal registers are displayed after each instruction An optional parameter may be entered to specify a number of instructions to be executed Entering T 10 will execute 10 instructions and then stop If an enabled breakpoint is reached before 10 instructions have executed the trace will stop immediately If the number of instructions to execute is entered as 0 the trace instruction will continue until a breakpoint is hit and will not count instructions If no parameter is entered only one instruction will be executed If the 8080 encounters a Halt instruction when tracing it will stop fetching opcodes and will no longer be controllable by the ICE A message will be displayed in this case and the system will need to be reset to restore normal operation Format T d16 U Untrace This command is similar to the trace command but the registers are not displayed after every instruction so execution is much faster The registers may be displayed when specific PC values are hit using printpoints Untracing will stop if the requested number of instructions has been executed or if an enabled breakpoint has been reached A parameter must be entered to specify a number of instructions to be executed Entering U 10 will execute 10 instructions and
19. f work which I couldn t justify It didn t seem useful enough to warrant the effort
20. gle memory location for scope loops W Write out memory as Intel Hex EA DA control start up behavior Go or Quit display help screen with command list Other differences L command displays hex data bytes along with instructions L command resolves branch target addresses M command checks for overlap between source and destination regions and changes move order if nec U command displays branch trace instead of the last few PC values as backtrace U and T commands check for of instructions 0 which disables instruction count limit U command displays total instructions executed since start of command 8080 HLTA halt status bit is monitored and a message is displayed if CPU is halted IC sockets enable using different 8080 chips or replacing PIC or RS 232 chip if damaged RS 232 level translator chip is used to provide better voltage levels to PC or terminal NICE uses 5V and Gnd R command read Intel Hex can operate at higher baud rates The manual for the NICE unit implies that a maximum of 300 baud can be supported without hardware handshaking I haven t seen any problems loading files at much higher baud rates with no hardware handshake Operating current NICE draws about 500 mA from the Z80 socket My unit draws much less The PALs and MCU used in the NICE draw much more current than the CPLD and PIC chip NICE supports assembly of instructions into RAM I don t This is a nice feature no pun intended but a lot o
21. hangs reset or power down the system and try again If you would prefer to have the ICE come up and start running automatically as a standard 8080 chip would use the EA command to enable AutoRun mode This setting will be saved in EEPROM and the next time you power up the 8080 will start executing from address 0 after reset ends The DA command can be used to disable AutoRun mode Note In my simple test system using the ICE instead of the 8080 by itself adds about 100 mA to the total system current Chapter 3 Command Line Interpreter Commands may be entered in either upper or lower case All numeric values such as addresses or counts are entered and displayed in hex When entering a 16 bit value d16 1 4 hex digits can be entered 1 or 2 digits can be entered for an 8 bit value d8 If a command accepts parameters it must be followed by a space The parameters can be separated by either a comma or a space Each command must be followed immediately by either a semicolon or a carriage return The command line can hold up to 31 characters Once that limit is reached you should hear a beep from the terminal Any additional characters entered will replace the last character on the line The command s on the command line will be executed when a carriage return is typed There are two prompts OK gt indicates the last command was accepted and executed without error ERR gt indicates that the last command was either not ac
22. minal emulation program such as TeraTerm or HyperTerm running on a PC or Mac Serial settings are 8 data bits no parity and 1 stop bit No hardware handshaking is needed Note The R command can process data and store it in the target system s memory at up to 19 2 K baud if the target system is running at 1 MHz or higher If a slower 8080 clock is used higher baud rates can cause a data overrun condition which will cause an error message to be displayed Using hardware handshake won t fix this as the PC takes too long to react to CTS going inactive In this case simply switch to a slower baud rate The ICE automatically detects the baud rate After powering up the unit hit Enter on the terminal to send acarriage return The ICE uses this to detect the baud rate and set its rate to match Supported rates are 300 600 1200 2400 4800 9600 and 19200 baud After the ICE has set its baud rate it will send the sign on message If you don t see this after pressing Enter reset or power down the system and try again Note The ICE s PIC microcontroller is reset by the same active high signal that resets the 8080 If there is a problem with the target system that causes this signal to stay high or float the ICE s microcontroller will be held in reset and will never send anything to the terminal The ICE will initially come up in Quit mode 8080 paused Press X to dump the registers and see if everything is OK If the register display
23. mory location intended for scope loops Read Intel Hex file into memory Substitute into memory Soft reset Trace Untrace Verify Write Intel Hex file from memory Examine change registers CS Checksum memory region Adds memory contents from start address to end address inclusive and displays 16 bit sum The result may exceed 16 bits but only the low 16 bits are displayed This should match the checksum generated by many EPROM programmers CS can also be used to check how reliable EPROM memory reads are by repeating the command and comparing the results Format CS startend Addresses entered as 1 4 hex digits Format CS Example OK gt CS 0000 03FF Checksum Ox73FD D Display memory Displays memory contents from start address to end Start address is truncated so that display always starts at nnnO Multiples of 16 bytes are displayed until end address is reached or passed ASCII equivalents for the data are also displayed A dash is inserted after the first 8 bytes Format D start end Addresses entered as 1 4 hex digits Both parameters are optional If no end address is entered 0x80 bytes are displayed If no start address is entered display begins at the next address after the end of the last D or L command This is the saved memory address So entering just D will start displaying from the end of the previous D command Example ASCII section is not correct OK gt D 0002 001
24. tered Hold requests are enabled as well The ICE comes up in Quit mode unless Autorun is enabled then it comes up in Go mode with the 8080 executing code All breakpoint and printpoint enables are cleared The saved memory address is set to OXFFFF More on this later The default PC starting value for the next G command is reset to 0000 Since the PIC gets reset whenever the 8080 is reset you need to send it a carriage return to allow the auto baud detection to complete If characters are not echoed to the terminal after you see the version text displayed reset or power down the target system and try again BP BPC EBP DBP EPP DPP EI DI EH DH EA DA CF RL ST Chapter 5 Go Mode Commands These commands can be entered in either mode except Q Set breakpoint address Set breakpoint count Enable breakpoint Disable breakpoint Enable printpoint Disable printpoint Clear all breakpoints and printpoints Enable interrupts Disable interrupts Enable hold requests DMA Disable hold requests Enable start up Autorun setting saved in EEPROM Disable start up Autorun setting saved in EEPROM hexadecimal sum and difference Clock frequency measurement 8080 clock Quit pause 8080 Repeat command line Status display Sleep insert delay BP Set breakpoint address Sets one of the three breakpoint addresses which are used by the trace and untrace commands Breakpoints end the current trace
25. then stop and display the registers If an enabled breakpoint is reached before 10 instructions have executed the untrace will stop immediately If the number of instructions to execute is entered as 0 the untrace instruction will continue until a breakpoint is hit and will not stop based on instruction count When the untrace command stops the total number of instructions executed during this one command is displayed This could be used to count for instance how many 8080 instructions are executed between system reset and a prompt appearing Ctl C can also be used to stop the untrace command If the 8080 encounters a Halt instruction when untracing it will stop fetching opcodes and will no longer be controllable by the ICE A message will be displayed in this case and the system will need to be reset to restore normal operation During an untrace command the 8080 s PC is monitored and when instructions that modify it such as branches calls and returns are executed their address is saved in a 12 entry FIFO buffer When the untrace command stops these instructions are displayed above the CPU registers and can be used to trace backwards from the current PC value to see what the recent sequence of calls or branches was before we stoppped A maximum of 12 of these instructions will be displayed If fewer than 12 were executed during the current untrace command only that number will be displayed Format U d16 V Verify compare memory
26. ther that address and pass count are currently enabled E or disabled D as a breakpoint The fourth value if displayed is a Pif the address is currently enabled as a printpoint The fourth line shows the current states of the two hardware enables If interrupts are enabled an I will be displayed If Hold requests are enabled an H will be displayed Note that both of these are always disabled in Quit mode regardless of what is displayed If start up Autorun is enabled an A will also be displayed Finally if the 8080 is currently executing instructions at full speed a Go command has been issued the word Running will be displayed Format ST Example OK gt ST gt 0123 33 E P gt 0654 66 D P gt 0982 99 E P IH Execution begins at gt 473F OK gt ST gt 0123 33 E P gt 0654 66 D P gt 0982 99 E P IH Running Z Sleep Causes the command processor to insert a variable delay before processing any other commands Format Z d8 The parameter is used to specify the desired delay in mSec Q n eS PS Cee AO ee EG Chapter 6 Quit Mode Commands These commands can only be used in Quit mode Generate and display 16 bit checksum of memory region Display memory Examine a single memory location intended for scope loops Fill memory Go Input from I O port List disassemble memory Move memory block Memory test destructive Output to I O port Put data into a single me
27. ts for an interrupt or reset Some code may normally sit in a halted state waiting for an interrupt then perform some action such as checking for a key press serial character received etc then after any required tasks have been performed execute a halt and wait for the next interrupt The ICE will not work properly when executing this type of code as the 8080 stops fetching instuctions when halted and cannot be controlled by the PIC The ICE can still be used in this type of system but the code containing the Halt instruction cannot be executed To avoid executing the Halt instruction as soon as the system is powered up disable autorun mode so that the 8080 will come up paused after reset To do this reset the system hit lt Enter gt to get the sign on message and prompt then type DA lt Enter gt This will disable autorun mode This setting is saved in EEPROM Now reset the system and hit lt Enter gt to get the sign on message and prompt Now you should be able to use the ICE to test memory access I O ports etc but don t execute the code that includes the Halt instruction as the ICE won t work after that Chapter 11 Differences between this unit and Nicolet s Z80 NICE New commands not present in NICE CF Measure clock frequency CS form 16 bit checksum of memory block E Examine and display a single memory location for scope loops MD Try to detect RAM and EPROM in target memory space P Put data into a sin
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