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| TOPIC -- Apple II -- Memory map of the Apple II ROMs
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Memory map of the Apple II ROMs
* $F800-$FFFF
Monitor. Handles screen I/O and keyboard input. Also has a disassembler, memory
dump, memory move, memory compare, step and trace functions, lo-res graphics
routines, multiply and divide routines, and more. This monitor has the cleanest
code of all the Apple II monitors. Every one after this had to patch the monitor
to add functions while still remaining (mostly) compatible. Complete source code
is in the manual.
• $F689-F7FC
Sweet-16 interpreter. Sweet-16 code has been benchmarked to be about half the size
of pure 6502 code but 5-8 times slower. The renumber routine in the Programmer's
Aid #1 is written in Sweet-16, where small size was much more important than
speed. Complete source code is in the manual.
• $F500-F63C and $F666-F668
Mini-assembler. This lets you type in assembly code, one line at a time, and it
will assemble the proper bytes. No labels or equates are supported--it is a MINI
assembler. Complete source code is in the manual.
• $F425-F4FB and $F63D-F65D
Floating point routines. Woz's first plans for his 6502 BASIC included floating
point, but he abandoned them when he realized he could finish faster by going
integer only. He put these routines in the ROMs but they are not called from
anywhere. Complete source code is in the manual.
• $E000-F424
Integer BASIC by Woz (Steve Wozniak, creator of the Apple II). "That BASIC, which
we shipped with the first Apple II's, was never assembled--ever. There was one
handwritten copy, all handwritten, all hand assembled." Woz, October 1984.
• $D800-DFFF
Empty ROM socket. There was at least one third party ROM add-on.
• $D000-D7FF
Programmer's Aid #1--missing from the original Apple II, this is a ROM add-on
Apple sold that contains Integer BASIC utilities such as high-resolution graphics
support, renumber, append, tape verify, music, and a RAM test. Complete source
code is in the manual.