2.2 KiB
Python Tools for A1B Relocation
This is a pair of simple (and far from optimized) Python tools that help you quickly and consistently move Apple 1 Integer BASIC (A1B) from it's normal location at $E000.
The source should be named a1basic.in and you should first run ./a1bmoveg.py. This will generate a file named a1basic.mod that lists the line numbers of all references to $Exxx.
The .mod file can be editted to comment out the lines you do not want to change. This can be a bit of trial and error (but not too much if you study the code). The example in this repository has the appropriate lines commented out.
Next you should edit ./a1bmovem.py so that Line 36 replaces all occurances of '$E' with the right value. I suggest using multiple of $2000 for relocation. (More about that in a minute.) You can then run this code and it will result in a file named a1basic.out that has the addressing modified.
There is one final step...
There is a reference in line 761 where a LDA #$76 is used followed by an ROL command (which has the effect of multiplying it by two resulting in A having a value of $EC). If you have stuck with a multiple of $2000, you just need to take the first hex digit, divide it by two, and replace the first hex digit in the constant.
At this point, you should have a source file that can be assembled and work from the selected location in memory.
I know you are safe moving to multiples of $2000. (I have working relations to $8000 and $A000.) Because of some of the tricks used there would definatly be problems not relocating to a page boundary. Can you select any page boundary? I'm not sure and would have to do some testing before I could say.
The fine print...
Copyright 2021 by Jim McClanahan W4JBM
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at
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