|The Acorn 6502 Microcomputer Kit||Firmware|
Timeline & people
Using the Monitor
Included in the Microcomputer
User’s manual is a listing of
the monitor program, which resides in the PROMs addressed at the
top two pages of the memory map ($FE00-$FFFF).
[The ‘$’ sign on this page and in
the code indicates that the following number is written in
This listing is well commented, but has a number of errors (missing labels, incorrect hex codes, etc.), which would seem to indicate that it has been produced manually, possibly by retyping from a handwritten assembly listing. There is also a significant change in the actual PROM code (the key debounce delay has been doubled by adding an instruction in the DELAY loop).
I have therefore edited a new copy of the monitor code in order to produce an assembler source file which can be assembled using Squak Valley Software’s Shareware TASM assembler. This includes equates for the monitor variables (in page $00), the stack (in page $01), and the RAM/IO memory and registers (in page $E0).
Here are the original text and the updated source and output files: