222 lines
8.9 KiB
Plaintext
222 lines
8.9 KiB
Plaintext
Call file manager with CATALOG opcode.
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Set new V value as default for future commands.
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Exit to caller.
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.np
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A57A-A59D FP command handler.
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Set ROM card, if any, for APPLESOFT (A5B2).
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If successful, coldstart DOS (9D84).
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Otherwise, set status flag to indicate INTEGER BASIC
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is active.
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Set primary filename buffer to "APPLESOFT".
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Set flags to indicate RAM APPLESOFT and coldstart.
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Go to RUN command handler.
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.np
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A59E-A5B1 INT command handler.
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Set ROM card, if any, for INTEGER BASIC (A5B2).
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If not successful, issue "LANGUAGE NOT AVAILABLE".
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Otherwise, clear RUN intercepted flag.
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Coldstart DOS (9D84).
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.np
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A5B2-A5C5 Set ROM to desired BASIC.
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(This routine is passed a $4C for APPLESOFT or a $20
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for INTEGER, since these bytes appear at $E000 in
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these BASICs. It will work regardless of which
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BASIC is onboard)
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If desired BASIC is already available, exit.
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Try selecting ROM card.
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If desired BASIC is now available, exit.
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Try selecting onboard ROM.
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If desired BASIC is now available, exit.
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Otherwise, exit with error return code.
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.np
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A5C6-A5DC EXEC command handler.
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Open the file (A2A3).
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Copy file buffer address to EXEC's buffer pointer at
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AAB4,AAB5.
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Set EXEC active flag (AAB3).
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Jump into POSITION command handler to skip R lines.
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.np
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A5DD-A60D POSITION command handler.
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Locate the open file buffer (A764).
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If not found, open one as a TEXT file.
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Copy buffer pointers to file manager parmlist.
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If R was not given on command, exit.
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A5F2 Otherwise, test R value for zero and exit if so.
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Decrement R value by one.
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Read file byte by byte until a carriage return (end
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of line - $8D) is reached.
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If at end of file, issue "END OF FILE" message.
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Otherwise, go to A5F2 to skip next record.
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.np
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A60E-A625 Write one data byte to file.
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Insure that BASIC is running a program (A65E).
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If not, close file and warmstart DOS.
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Set up file manager parmlist to write the data byte
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to the open file.
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Call file manager and exit.
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.np
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A626-A65B Read one data byte from file.
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Insure that BASIC is running a program (A65E).
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If not, close file and warmstart DOS.
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Set CSWL intercept state to 6 (skip prompt character)
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A630 Read next file byte (A68C).
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If not at end of file, go to A644.
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Otherwise, close file.
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If state is not 3 (EXEC) issue "END OF DATA" message.
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Exit to caller.
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A644 If data byte is lower case character, turn its most
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significant bit off to fool GETIN routine in monitor.
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Store data byte in A register saved at entry to DOS.
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Using line index, turn high bit back on in previous
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data byte stored at $200 (input line buffer) to make
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it lower case if necessary.
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Exit DOS (9FB3).
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.np
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A65E-A678 Test to see if BASIC is running a program or is in
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immediate command mode.
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If active BASIC is INTEGER, go to A672.
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If line number is greater than 65280 and prompt is
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"]" then APPLESOFT is in immediate mode.
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Otherwise, it is executing a program.
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Exit to caller with appropriate return code.
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A672 Check $D9 to determine whether BASIC is executing a
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program and exit with proper return code.
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.np
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A679-A681 Close current file and warmstart DOS.
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.np
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A682-A68B EXEC read one byte from file.
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Select EXEC file buffer.
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Copy file buffer addresses to file manager parmlist.
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Set state to 3 (input echo).
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Go to A62D to read a file byte.
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.np
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A68C-A69C Read next text file byte.
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Set up file manager parmlist to read one byte.
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Call file manager driver.
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Return to caller with the data byte.
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.np
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A69D-A6A7 Set $40,$41 to point to EXEC file buffer.
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.np
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A6A8-A6C3 File manager driver routine.
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Call the file manager itself (AB06).
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If no errors, exit to caller.
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Otherwise, point $40,$41 at file buffer.
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If found, release it by storing a zero on the file
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name field.
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If error was not "END OF DATA", print error message.
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Otherwise, pretend a $00 was read and return to
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caller.
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.np
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A6C4-A6D4 Miscellaneous error messages.
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A6C4 "COMMAND SYNTAX ERROR"
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A6C8 "NO FILE BUFFERS AVAILABLE"
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A6CC "PROGRAM TOO LARGE"
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A6D0 "FILE TYPE MISMATCH"
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.np
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A6D5-A701 Error handler.
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Set warmstart flag and clear status (BFE6).
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If APPLESOFT ONERR is active, go to A6EF.
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Otherwise, print RETURN BELL RETURN.
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Print text of error message (A702).
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Print another RETURN.
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A6EF Replace DOS intercepts.
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If a BASIC program is in execution, pass error code
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to BASIC's error handler.
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Otherwise, warmstart BASIC.
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.np
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A702-A719 Print text of error message.
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Using the error number as an index, print the message
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text from the message table (A971) byte by byte.
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Last character has most significant bit on.
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.np
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A71A-A742 Complete file manager parameter list.
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Copy Volume value to parmlist.
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Copy Drive value to parmlist.
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Copy Slot value to parmlist.
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Copy address of primary filename buffer to parmlist.
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Save file buffer address in $40,$41.
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Return to caller.
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.np
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A743-A74D Copy primary filename to file buffer filename field.
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.np
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A74E-A75A Copy current buffer pointers to file manager parmlist
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Copy file manager workarea buffer pointer.
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Copy T/S List sector buffer pointer.
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Copy data sector buffer address.
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Copy next file buffer link address.
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Return to caller.
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.np
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A75B-A763 Reset state to 0 and set warmstart flag.
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.np
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A764-A791 Locate an open or free file buffer.
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Assume there are no free file buffers by zeroing $45.
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Point $40,$41 at first buffer on chain.
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Go to A773.
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A76E Point $40,$41 at next buffer on chain.
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If at end of chain, exit with file not open code.
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A773 Get first byte of filename field.
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If zero (file buffer free), save file buffer address
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at $44,$45 as an available buffer and go to A76E.
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Otherwise, see if name in primary filename buffer
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matches the name in this file buffer.
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If not, go to A76E to get next buffer.
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If so, return to caller with open file found code.
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.np
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A792-A799 Point $40,$41 at first file buffer on chain.
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.np
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A79A-A7A9 Point $40,$41 at next file buffer on chain.
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.np
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A7AA-A7AE Get first byte of file name in file buffer.
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.np
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A7AF-A7C3 See if current buffer belongs to EXEC.
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Is EXEC active?
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If not, exit.
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If so, does current buffer address match EXEC's?
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Return to caller with appropriate code.
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.np
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A7C4-A7D3 Check file type.
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Does file type of open file match desired file type?
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If so, exit.
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Otherwise, turn lock bit off and test again.
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If ok, exit.
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Otherwise, close file and issue "FILE TYPE MISMATCH".
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.np
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A7D4-A850 Initialize (build) DOS file buffer chain.
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Set $40,$41 to point to first buffer.
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Set counter to MAXFILES value.
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A7E5 Store zero on filename field to mark as free.
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Set up link pointers in buffer to point to file
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manager workarea (45 bytes prior to filename field).
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Set up link pointer to T/S List sector buffer (-256
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bytes from file manager workarea buffer).
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Set up link pointer to data sector buffer 256 bytes
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before that.
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Decrement counter.
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If zero, go to A82D to set HIMEM.
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Otherwise, set link to next file buffer as 38 bytes
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prior to data sector buffer.
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Go to A7E5 to set up next buffer.
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A82D Set link of last buffer to $0000.
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If INTEGER BASIC is active, go to A846.
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Otherwise, set APPLESOFT's HIMEM and STRING START
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pointers in zeropage to point just below the last
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buffer.
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Exit to caller.
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A846 Set INTEGER BASIC's HIMEM and PROGRAM START pointers
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to point just below the last buffer.
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Exit to caller.
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.np
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A851-A883 Replace DOS keyboard/video intercept vectors.
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Is DOS keyboard (KSWL) vector still set?
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If so, go to A86A.
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Otherwise, save current KSWL vector ($38,$39) at
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AA55,AA56 and replace with DOS intercept routine's
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address.
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A86A Is DOS video (CSWL) vector still set?
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If so, exit to caller.
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Otherwise, save current CSWL vector ($36,$37) at
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AA53,AA54 and replace with DOS intercept routine's
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address.
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Exit to caller.
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.nx ch8.4
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