COPY O.S.  Atari 6502
Version 1.2 (HTML conversion by SysOp Fox-1, July 2002)
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Download Download the "COPY O.S." utility.

Barry Gordon 1/92  

This program will copy the Operating System from an Atari XL/XE to disk for use with an EPROM burner. The Atari XL/XE Operating System chip is layed out in four sections:

-ROM Address- -Computer Address- -XL/XE OS Function-
$0000 - $0FFF $C000 - $CFFF Interrupt handlers, misc routines
$1000 - $17FF $5000 - $57FF Self Test code (enabled by PORTB)
$1800 - $1FFF $D800 - $DFFF Floating Point routines
$2000 - $3FFF $E000 - $FFFF Operating System

The Classic 800 OS had no Self Test memory, and did not allow ROM banking of the $C000 memory. Custom Operating Systems for the XL/XEs are usually based on this OS and will use these two areas to their fullest advantage.

COPYOS will create a file exactly 16,390 ($4006) bytes long. It will contain the above listed areas in the ROM address format, preceeded by a binary file header. This file can then be modifed and used by an EPROM burner to create a new OS chip.

The Self Test routines and the Floating Point routines were given special consideration when writing this program. The Self Test routines (which must be banked in by clearing Bit 7 of PORTB) are automatically disabled by the OS during disk I/O. The Floating Point routines are automatically banked out by the OS when a parallel device is accessed (i.e. a Hard Drive). The high-speed floppy operations in the Black Box also disable the Floating Point routines during disk I/O. Both of these routines are copied to a safe place in memory and written out to disk from there.

This program was not written for purposes of pirating copyrighted Operating System chips, but rather to encourage experimentation with firmware programming.

Happy EPROM burning!

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