mirror of
https://github.com/iKarith/beneath-apple-dos.git
synced 2024-06-01 01:41:37 +00:00
1d9b739d80
Looks like CH4 is somewhat hosed, a small amount of bit rot? Doesn't look like too much actually.
409 lines
16 KiB
Plaintext
409 lines
16 KiB
Plaintext
.np
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AF4B-AF5D Prepare for RWTS call with a T/S List sector.
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Copy address of T/S List buffer to RWTS parmlist.
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Get track/sector of sector.
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Exit to caller.
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.np
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AF5E-AFDB Read a T/S List sector to file buffer.
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(CARRY flag is set at entry to indicate whether the
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first T/S List for the file is wanted (C=0) or the
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next (C=1).
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Memorize carry flag entry code.
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Checkpoint current T/S List sector if necessary.
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Set up for RWTS (AF4B).
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Select T/S List buffer (AF0C).
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Is first or next wanted?
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If first, go to AFB5 to continue.
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Otherwise, get link to next T/S List from this one.
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If link is non-zero, use it to find next one and go
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to AFB5.
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Otherwise, we are out of T/S Lists for this file.
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If we are reading file, exit with error code.
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Otherwise, allocate a new sector (B244).
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Point old T/S List sector to new one's track/sector.
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Write old T/S List sector back to disk.
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Zero the buffer to form new T/S List sector.
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Compute and store the relative sector number of the
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first sector listed in this sector at +5,+6 into the
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buffer.
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Set RWTS opcode to write new T/S List sector to disk.
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AFB5 Set RWTS opcode to read old T/S List (unless we just
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allocated it above).
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Set track and sector and call RWTS to read old list
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or write new list.
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Compute relative sector number of last sector (plus
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one) in this list and store in workarea.
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Exit to caller with normal return code.
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.np
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AFDC-AFE3 Read a data sector.
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Set up for RWTS (AFE4).
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Set RWTS READ opcode and go to RWTS driver to do it.
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.np
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AFE4-AFF6 Prepare for RWTS with data sector.
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Copy address of data sector buffer to RWTS parmlist.
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Get its track/sector.
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And exit to caller.
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.np
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AFF7-B010 Read/write the VTOC buffer.
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AFF7 Read VTOC entry, go to AFFD.
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AFFB Write VTOC entry, fall through.
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AFFD Common code.
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Copy VTOC sector buffer address to RWTS parmlist.
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Get its track number and use sector $00.
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Exit through RWTS driver.
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.np
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B011-B036 Read a directory sector.
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(If CARRY flag is zero on entry, read first directory
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sector. If CARRY is one, read next)
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Memorize entry code.
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Set buffer pointers (B045).
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First or next?
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If first, get track/sector of directory sector from
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VTOC at offset +1,+2.
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Otherwise, get track/sector from directory sector at
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offset +1,+2. If track is zero, exit with error code
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(end of directory).
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Call RWTS to read sector.
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Exit with normal return code.
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.np
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B037-B044 Write directory sector.
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Set buffer pointers.
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Find its track/sector in workarea.
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Exit through RWTS to write it.
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.np
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B045-B051 Prepare for RWTS for directory buffer.
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Copy directory buffer address to RWTS parmlist.
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Exit to caller.
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.np
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B052-B0B3 Read/Write Track/Sector (RWTS) driver.
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Set track/sector in RWTS parmlist.
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B058 Set command code (read,write,etc.)
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If writing, set flag (B5D5).
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Set volume number expected in parmlist.
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Set slot*16 in parmlist.
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Set drive in parmlist.
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Set sector size in parmlist.
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Set IOB type in parmlist ($01).
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Call RWTS, passing parmlist pointer.
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Copy true volume found to file manager parmlist.
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Reset volume expected field in RWTS parmlist.
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If an error did not occur, exit to caller.
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Otherwise, get return code.
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Translate vol mismatch to rc=7, write protected to
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rc=4 and all other errors to rc=8 (I/O error).
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Exit file manager now.
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.np
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B0B6-B133 Read next data sector (if necessary).
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Is the current file position in the current data
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sector now in memory?
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If so, go to B12C.
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Otherwise, checkpoint data sector buffer.
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Is the current file position prior to or after this
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T/S List's domain?
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If not, go to B0F3.
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Otherwise, read each T/S List for the file, starting
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with the first, until the proper one is found.
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If it is never found, exit with error (ran off end of
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file reading).
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B0F3 Data is in this T/S List sector.
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Compute the displacement to the proper entry in this
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T/S List sector.
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Select the T/S List buffer.
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Get the track of the data sector wanted.
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If non-zero, go to B114.
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Otherwise, if not writing, exit with error (no data
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to read there).
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If writing, allocate a new sector and store its
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track/sector location in the list at this point
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(B134).
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Go to B120.
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B114 Read old data sector, using the track/sector found
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in the T/S List entry.
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B120 Save number of sector last read in workarea.
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B12C Select data buffer.
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Get byte offset and exit normally to caller.
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.np
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B134-B15A Add a new data sector to file.
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Allocate a sector (B244).
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Put track/sector numbers in T/S List entry.
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Select data buffer and zero it.
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Set flags to indicate that the T/S List sector and
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the data sector buffer require checkpoints.
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Exit to caller.
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.np
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B15B-B193 Increment record number and byte offset into file.
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Copy current record number and byte offset to file
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manager parameter list to pass back to caller.
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Increment byte offset in workarea.
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If byte offset equals record length, set byte offset
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back to zero and increment record number.
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Return to caller.
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.np
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B194-B1A1 Increment file position offset.
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Increment byte offset into current sector by one.
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If at end of sector, increment sector number by one.
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Return to caller.
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.np
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B1A2-B1B4 Copy and advance range address.
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Copy range address from file manager parmlist to $42.
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Increment range address in parmlist for next time
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through.
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Return to caller.
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.np
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B1B5-B1C8 Decrement range length.
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Decrement range length in file manager parmlist by
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one.
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If zero, exit file manager.
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Otherwise, exit to caller.
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.np
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B1C9-B21B Locate or allocate a directory entry in the catalog.
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Read the VTOC sector (AFF7).
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Set $42,$43 to point to file name we are looking for.
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Set pass number to one (locate file).
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B1D8 Initialize directory sector offset (first sector).
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B1E1 Increment sector offset.
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Read directory sector.
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If at end of directory, go to B23A.
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Set entry index to first file entry.
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B1EB Get track.
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If deleted, skip entry, go to B217.
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If empty, end of directory, go to B212.
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Advance index to filename in directory.
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Compare against filename wanted.
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If they match, return entry index and exit.
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If not, advance index to next entry in sector and
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loop back to B1EB.
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If at end of sector, go to B1E1 to get next sector.
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B212 If pass number is one, go to B1D8 to start second
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pass.
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B217 If pass number is one, go to B20B to skip entry.
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If second pass, fall through to allocate entry.
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.np
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B21C-B22F Copy file name to directory entry.
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Advance index to file name field in directory entry.
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Copy 30 byte filename to directory entry.
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Reload directory index and return to caller.
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.np
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B230-B239 Advance index to next directory entry in sector.
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Add 35 (length of entry) to index.
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Test for end of sector and return to caller.
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.np
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B23A-B243 Switch to second pass in directory scan.
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If on pass one, switch to pass 2 and go to B1D8.
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If on pass two, exit file manager with "DISK FULL"
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error.
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.np
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B244-B2C2 Allocate a disk sector.
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Is there a track currently allocated to this file?
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If not, go to B26A to find a track with free sectors.
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B249 Otherwise, decrement sector number to get next
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possible free sector number.
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If there are no more sectors on this track, go to
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B265 to find a new track.
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Otherwise, rotate the track bit mask by one position
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and get the bit for this sector.
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If the sector is in use, loop back to B249.
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Otherwise, add one to file's sector count.
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Pass back sector number (track number is at B5F1).
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And return to caller.
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B265 Indicate no track is being used at present.
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B26A Reset allocation flag to allow at least one complete
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search of all tracks for some space.
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Read VTOC sector.
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B272 Get last track allocated from and add direction value
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to get next track to examine (+1 or -1).
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Are we back to track 0?
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If so, go to B284.
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Otherwise, are we past track 34?
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If so, reverse direction and go to B28E.
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B284 Is this the second time we have come to track 0 ?
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(check allocation flag).
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If so, exit with "DISK FULL" error.
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Otherwise, set allocation flag to remember this.
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Set direction to forward (+1).
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B28E Begin at directory track (17 + or - 1).
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Compute bit map index (tracknumber*4).
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Copy track bit map from VTOC to workarea, watching
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to see if all four bytes are zero (track is full).
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In any case, set all four bytes in VTOC to zero
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(allocate all sectors).
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If no free sectors in the track, go to B272 to try
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next track.
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Otherwise, write VTOC to disk to insure file's
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integrity.
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Set sector number to last sector in track.
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Go to B249 to allocate one of its free sectors to
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the file.
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.np
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B2C3-B2DC Release pre-allocated sectors in current track and
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checkpoint the VTOC.
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Has a track been allocated to the file?
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If not, exit to caller.
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Otherwise, read VTOC.
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Get next sector which could have been used (number
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of times track map was shifted during allocation).
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Call B2DD to shift track bit map back and merge it
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back into the VTOC bit map.
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Indicate no track has been allocated.
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Exit to caller.
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.np
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B2DD-B2FF Free one or more sectors by shifting mask in file
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manager's allocation area back into VTOC bit map.
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(If CARRY is set, current sector is freed also)
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Rotate entire 4 byte track bit mask once.
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Repeat for as many sectors as were allocated.
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Compute index into VTOC for this track's map.
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If zero, exit.
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Merge ("OR") file manager's bits with those already
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in VTOC, freeing sectors which were never used by
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the file.
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Return to caller.
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.np
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B300-B35E Calculate file position.
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Set record number passed in file manager parmlist
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in workarea and in sector offsets.
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Clear sector offset high part.
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Perform a 16 bit multiply as follows:
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3 byte file position = record number times record
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length.
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Add the byte offset from the parmlist into the three
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byte file position value (B5E4,B5E5,B5E6).
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Return to caller.
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.np
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B35F-B37D Error exits.
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B35F RC=1 "LANGUAGE NOT AVAILABLE"
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B363 RC=2 "RANGE ERROR" (bad opcode)
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B367 RC=3 "RANGE ERROR" (bad subcode)
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B36B RC=4 "WRITE PROTECTED"
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B36F RC=5 "END OF DATA"
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B373 RC=6 "FILE NOT FOUND"
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B377 RC=9 "DISK FULL" (all files closed)
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B37B RC=A "FILE LOCKED"
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.np
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B37F-B396 Exit file manager.
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B37F Exit with no errors.
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Get return code of zero.
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Clear carry flag and go to B386.
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B385 Set carry flag to indicate error.
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B386 Save return code in parmlist.
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Clear monitor status register ($48) after RWTS has
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probably tromped on it.
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Save file manager workarea to file buffer (AE7E).
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Restore processor status and stack register.
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Exit to original caller of file manager.
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.np
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B397-B3A3 File manager scratch space.
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B397 Track/sector of current directory sector (2 bytes).
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B39B S register save area.
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B39C Directory index.
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B39D Catalog line counter/Directory lookup flag/Etc.
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B39E LOCK/UNLOCK mask/Allocation flag/Etc.
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B3A0 Four byte mask used by INIT to free an entire track
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in the VTOC bit map.
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.np
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B3A4-B3A6 Decimal conversion table (1,10,100).
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.np
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B3A7-B3AE File type name table used by CATALOG.
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File types are: T,I,A,B,S,R,A,B, corresponding to
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hex values: $00, $01, $02, $04, $08, $10, $20, and
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$40 respectively.
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.np
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B3AF-B3BA ASCII text "DISK VOLUME " backwards. Used by CATALOG.
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.np
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B3BB-B4BA VTOC sector buffer.
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B3BC Track/sector of first directory sector.
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B3BE DOS release number (1, 2, or 3).
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B3C1 Volume number of diskette.
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B3E2 Number of entries in each T/S List sector.
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B3EB Track to allocate next.
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B3EC Direction of track allocation (+1 or -1)
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B3EF Number of tracks on a disk.
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B3F0 Number of sectors on a disk.
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B3F1 Sector size in bytes (2 bytes)
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B3F3 Track 0 bit map
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B3F7 Track 1 bit map
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etc.
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B47B Track 34 bit map
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.np
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B4BB-B5BA DIRECTORY sector buffer.
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B4BC Track/sector of next directory sector.
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B4C6 First directory entry and
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Track of T/S List
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B4C7 Sector of T/S List
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B4C8 File type and lock bit
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B4C9 Filename field (30 bytes)
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B4E7 Size of file in sectors (including T/S List(s)).
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.np
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B5BB-B5D0 File manager parameter list.
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B5BB Opcode
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B5BC Subcode
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B5BD Eight bytes of variable parameters depending on
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opcode.
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B5C5 Return code.
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B5C7 Address of file manager workarea buffer.
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B5C9 Address of T/S List sector buffer.
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B5CB Address of data sector buffer.
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B5CD Address of next DOS buffer on chain (not used).
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.np
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B5D1-B5FD File manager workarea.
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B5D1 1st T/S List sector's track/sector.
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B5D3 Current T/S List sector's track/sector.
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B5D5 Flags: 80=T/S List needs checkpoint
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40=Data sector needs checkpoint
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20=VTOC sector needs checkpoint
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02=Last operation was write
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B5D6 Current data sector's track/sector.
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B5D8 Directory sector index for file entry.
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B5D9 Index into directory sector to directory entry for
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file.
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B5DA Number of sectors described by one T/S List.
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B5DC Relative sector number of first sector in list.
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B5DE Relative sector number +1 of last sector in list.
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B5E0 Relative sector number of last sector read.
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B5E2 Sector length in bytes.
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B5E4 File position (3 bytes) sector offset, byte offset
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into that sector.
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B5E8 Record length from OPEN.
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B5EA Record number.
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B5EC Byte offset into record.
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B5EE Number of sectors in file.
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B5F0 Sector allocation area (6 bytes).
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Next sector to allocate (shift count)
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Track being allocated
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Four byte bit map of track being allocated, rotated
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to next sector to allocate.
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B5F6 File type.
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B5F7 Slot number times 16.
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B5F8 Drive number.
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B5F9 Volume number (complemented).
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B5FA Track number.
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.np
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B5FE-B5FF Not used.
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.np
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B600-B6FF Start of Boot 2/RWTS image.
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B600 Boot 1 image which can be written to INITed disks
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on track 0, sector 0.
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B65D DOS 3.3 patch area.
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B65D APPEND patch flag.
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B65E APPEND patch. Come here when file manager driver
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gets an error other than end of data.
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Locate and free the file buffer.
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Clear the APPEND flag.
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Get the error number and go print error (A6D2).
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B671 APPEND patch. Come here from APPEND command handler
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to increment record number if APPEND flag is set and
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to clear the flag. Exit through POSITION.
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B686 VERIFY patch. Come here from I/O a range of bytes
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routine to exit through VERIFY after SAVE or BSAVE.
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B692 APPEND patch. Come here from file manager driver if
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return code was END OF DATA.
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Test the file position for zero.
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If non-zero, set APPEND flag on and return to caller.
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If zero (at start of file), copy record number and
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byte offset to file manager parmlist and return a
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zero data byte to caller.
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B6FE Page address of first page in Boot 2.
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B6FF Number of sectors (pages) in Boot 2.
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.br
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.nx ch8.7
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\x00 |