Disc Filing System User Guide
Contents
1. 1 20 will work with DFS 2 10 obvious exceptions being protected discs which employ direct access of the 8271 disc controller DFS 2 10 uses the same commands as DFS 1 20 but some commands have been slightly modified as detailed below There is no utilities disc with DFS 2 10 the FORM lt 40 80 gt and VERIFY utilities which are disc based with DFS 1 20 are filing system commands with DFS 2 10 references to a utilities disc which occur within the user guide should be ignored DFS 2 10 contains several new commands which are not present in DFS 1 20 see below Throughout this text references to ROM read only memory should be understood to include any non volatile memory device with ROM compatible connections and access time such as a 2764 27128 or 27256 EPROM with 250ns access time DFS 2 10 only Commands CLOSE Purpose closes all sequential files All disc file data held in RAM output buffers will be copied to the disc CLOSE has the same effect as the CLOSE 0 in BASIC Example CLOSE Notes The minimum abbreviation for CLOSE is CL EX lt dir gt Purpose to display information about the specified directory The information is displayed across the screen in hexadecimal in the following order reading from left to right lt directory name gt lt file name gt protection attribute load address execution address length in bytes start sector number Examples EX might give BOOT L FF1900 FF8023 00003B2. 205 MENU L FF1900 FF1900 000332 00B EX D might give D ROB FF1900 FFB023 000695 07B D WORK 000000 000000 000015 2A9 If no lt dir gt is given the currently selected directory is examined Associated commands CAT INFO Support Group Application Note No 023 Issue 1 2 Support Group Application Note No 023 Issue 1 9th July 1992 FORM lt 40 80 gt lt drive gt lt drive gt lt drive gt lt drive gt etc Purpose this command is used to format a disc enabling it to be used with DFS 2 10 or with earlier DFS versions The command has the same function as the utilities described in chapter 7 of the user guide but has slight operating differences as detailed below Examples FORM 40 Format which drive 0 GO Y N Y Formatting drive 0 track lt track number gt runs from amp 00 to amp 27 This formats a 40 track disc in drive 0 FORM 80 Format which drive 0 GO Y N Y Formatting drive 0 track lt track number gt runs from amp 00 to amp 4F This formats an 80 track disc in drive 0 FORM 80 0 2 GO Y N Y Formatting drive 0 track lt track number gt Formatting drive 2 track lt track number gt Formats both sides of an 80 track disc in drive 0 FORM 800 2 1 3 GO Y N Y Formatting drive 0 track lt track number gt Formatting drive 2 track lt track number gt Formatting drive 1 track lt track number gt Formatting drive 3 track lt track number gt Formats bo
3. 3 Issue 1 9th July 1992 ROMS lt rom id gt Purpose Produces a list of the installed ROMs The information displayed consists of the ROM socket number rom id see Notes below the ROM type the title of the software in the ROM and its version number if appropriate If a lt rom id gt is included then information is displayed just for the specified ROM if it is present The ROM can be identified by its socket number or by its title The ROM type is displayed as L for a language ROM S for a service ROM eg a filing system ROM or SL for a service language ROM Examples model B only ROMS Rom 15 L BASIC Rom 11 S DFS 2 0 catalogues the installed ROMs ROM 11 Rom 11 S DFS 2 0 catalogues the ROM with id number 11 ROMS BASIC Rom 15 L BASIC catalogues the BASIC rom Notes The ROM socket numbers for the BBC Micro Model B are detailed under the FX142 command heading in chapter 43 of the BBC Micro System User Guide VERIFY lt drive gt lt drive gt lt drive gt lt drive gt etc Purpose checks the integrity of each sector of a disc FORM lt 40 80 gt performs an automatic verification of each track immediately after formatting it Examples VERIFY Verify which drive 1 Verifying drive 1 track lt track number gt verifies drive 1 lt track number gt runs from amp 00 to amp 27 or amp 00 to amp 4F as appropriate VERIFY 0 Verifying drive 0 track lt track number
4. 9th July 1992 Issue 1 Author Support Group Application Note a Number 023 Cor ww Disc Filing System User Guide Addendum This addendum details the differences between the Acorn 1770 Disc Filing System DFS and DFS 1 20 as described in the Disc Filing System user Guide issue 2 Applicable Related Hardware Application BBC B Notes BBC B Copyright Acorn Computers Limited 1992 Every effort has been made to ensure that the information in this leaflet is true and correct at the time of printing However the products described in this leaflet are subject to continuous development and improvements and Acorn Computers Limited reserves the right to change its specifications at any time Acorn Computers Limited cannot accept liability for any loss or damage arising from the use of any information or particulars in this leaflet ACORN ECONET and ARCHIMEDES are trademarks of Acorn Computers Limited Support Group Acorn Computers Limited Acorn House Vision Park Histon Cambridge CB44AE Support Group Application Note No 023 Issue 1 9th July 1992 General The Acorn 1770 DFS DFS 2 10 is designed to be compatible with the Acorn DFS version 1 20 and earlier versions DFS 2 10 works with a 1770 disc controller whereas DFS 1 20 operates with an 8271 disc controller Programs ROMs which directly access an 8271 disc controller will not work with an DFS 2 10 disc system Most discs that work with DFS
5. command will format the disc size given by the FORM lt 40 80 gt parameter Note that an 80 track drive cannot correctly format discs for 40 track drives and vice versa The command VERIFY will check a properly formatted 40 track disc in an 80 track drive set to 40 track operation Error Messages The Drive Fault error message amp C5 has been deleted Keyboard Links The interpretation of the keyboard link settings varies slightly from the description given in chapter 12 as shown below Link 3 Link 4 Step time 0 0 6 ms 1 0 12 ms 0 1 20 ms 1 1 30 ms default BBC Micro 800k drives give optimum performance with a stepping rate of 6 ms Drive stepping rates can be set with the FX255 command The the BBC Micro User Guide for details Support Group Application Note No 023 Issue 6 Support Group Application Note No 023 Issue 1 9th July 1992 Special Starting Procedure for Protected Discs Some discs use specially formatted sectors tracks which are normally reported as faulty by the DFS This means that BACKUP COPY etc will not read the disc and so the owner of the disc will be unable to reproduce it Certain formats which were used in conjunction with a 8271 disc controller IC cannot normally be read by a 1770 disc controller The special loading program which is on a protected disc will not therefore work on a machine using 1770 DFS The model B is highly compatible with model B machines the late
6. gt verifies drive 0 Associated commands FORM40 FORMS80 Notes if the first attempt to verify a track fails a will be displayed with the track number If the track fails to verify after five more attempts verification is abandoned and a disc fault is reported The minimum abbreviation for the VERIFY command is V Support Group Application Note No 023 Issue 5 Support Group Application Note No 023 Issue 1 9th July 1992 Changed Commands The following keywords to not behave exactly as described in chapter 6 of the user guide BACKUP DESTROY ENABLE BACKUP and DESTROY employ a similar prompt system to the FORM lt 40 80 gt command see above They do not need to be enabled but prior use of the ENABLE command will result in the GO Y N prompt being omitted DRIVE lt drive gt The syntax of this command has been changed to DRIVE lt drive gt 40 80 The new parameter allows an 80 track drive to read 40 track discs by double stepping the drive head Examples DRIVE 1 40 switches drive 1 of an 80 track drive to 40 track disc mode read only DRIVE 1 80 sets drive 1 to 80 track operation Notes DRIVE lt drive gt 40 and DRIVE lt drive gt 80 should not be used with a 40 track disc drive Attempting to write using an 80 track drive whilst in 40 track mode will result in a Disc read only error message FORM ignores the 40 track mode selected with DRIVE The FORM lt 40 80 gt
7. r OS version 2 00 fitted to model B does not normally affect its compatibility However some protected programs include an additional test which reads the machine Operating System type code by using INKEY 256 or its OSBYTE equivalent Unfortunately this test fails on the model B OS 2 00 CTRL Z BREAK A special boot loading mode CTRL Z BREAK has been introduced into 1770 DFS 2 20 and later This new mode uses an alternative 8271 emulation technique which may enable otherwise unloadable discs to be booted in successfully In addition the special boot mode returns 1 to the INKEY 256 command and so will improve the compatibility of the model B with software written for model B machines When to use CTRL Z BREAK Normally discs are booted in by using SHIFT and BREAK or SHIFT D BREAK if DFS is not your default filing system This procedure will automatically EXEC a file called BOOT from drive 0 Always try SHIFT lt D gt BREAK first If SHIFT lt D gt BREAK fails to load a disc try using the special boot mode SHIFT Z BREAK or even CTRL SHIFT Z BREAK hold down CTRL SHIFT and Z together press and release BREAK quickly followed by CTRL then release SHIFT and Z together If none of these options will run the disc program you should check with the software supplier or the dealer from whom you bought the disc about its compatibility with 1770 DFS Support Group Application Note No 023 Issue 7
8. tempts formatting is abandoned and a disc fault reported The minimum abbreviation for FORM is FO FREE lt drive gt Purpose to display for the specified drive the number of files that can be added to the catalogue together with the amount of space used and left to be used in terms of sectors in hexadecimal and bytes in decimal Examples FREE 31 Files 31E Sectors 204 288 Bytes Free 00 Files 002 Sectors 512 Bytes Used displays free space in the current drive FREE 1 00 Files 038 Sectors 14 336 Bytes Free 31 Files 2E8 Sectors 190 464 Bytes Used displays free space in drive 1 Associated commands COMPACT MAP Notes the minimum abbreviation for FREE is FR MAP lt drive gt Purpose to display a map of the free space available on the disc The format is a list of pairs of numbers of the form lt Sector address gt lt length in sectors gt Examples MAP Address Length 010 004 10A 023 180 050 displays the free space map on the current drive MAP 1 Address Length 045 001 119 080 200 03A displays the free space map on drive 1 Associated commands COMPACT FREE EX Notes If there are a large number of entries in the free space map then the disc contents have become fragmented and compaction is needed use the COMPACT command The minimum abbreviation for MAP is MA Support Group Application Note No 023 Issue 4 Support Group Application Note No 02
9. th sides to 80 track discs in drives 0 and 1 of a dual disc drive Associated commands ENABLE VERIFY Notes It is not possible to format discs for a 40 track drive in an 80 track drive nor is it possible to format discs for an 80 track drive in a 40 track drive 40 track drives use 48 tracks per inch 80 track drives use 96 tracks per inch The formatting process uses some I O processor RAM space approximately 3 5K bytes above OSHWM usually PAGE in BASIC so if you wish to save a program you should do so before formatting a disc When formatting a disc screen memory corruption may occur in any non shadow display mode for values of OSHWM greater than amp 2200 For example formatting a disc using a BBC Micro with DFS 2 10 and ADFS installed and with a second processor connected and switched on will corrupt screen memory in display MODEs 0 1 or 2 It is not necessary to insert a space before any of the parameters following FORM Pressing anything other than Y in answer to the GO Y N prompt results in the formatting sequence being abandoned Using the ENABLE command immediately before the FORM command results in the GO Y N prompt being omitted from the sequence Support Group Application Note No 023 Issue 3 Support Group Application Note No 023 Issue 1 9th July 1992 If formatting a track fails at the first attempt a is displayed after the track number concerned If the track fails to format after six at
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