MIKBUG REV. 9 for Apple-1 with 6800

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MIKBUG REV. 9 for Apple-1 with 6800

In case anyone is interested, I've attached my port of MIKBUG REV. 9 to the 6800 Apple-1.

This version is adapted to use the RAM-based IRQ vectors in my variant of a1mon68, but it should work with unmodified a1mon68 as well, as long as IRQs (e.g. SWI) are not used.

Plain text iconMIKBUG.txt

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Micro BASIC Plus

Using the `L` command it's possible to load software from S-Records like the TSC 4K Micro BASIC Plus 4K variant found here (manual), which seems to be set up to use the MIKBUG entry points for I/O, though I'm not sure it's designed for this version so I don't know how well it will work without patching (I've been able to load and start it at entry point $0100, type in and run a simple Hello World program, but that's about it).

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6800 Co-Res Assembler

It's also possible to load the version of the co-res assembler found here  (reference 1, reference 2).

This actually works (tested under an emulator); I have been able to use it to assemble code successfully.

If the system has RAM beyond $7FFF then a patch is needed to adjust the address at locations $53,$54 to avoid symbol table overflow error (221). Also, for Apple-1 the $7F (DEL) at $10F9 should be replaced with $0D (CR). The following patch (to be loaded after the co-res S-record) does both of these things, and also sets the PC to the warm-start entry point so that the `G` command will avoid initialization that undoes these changes.

The procedure for loading this from MIKBUG is:

  1. Load and run cores assembler using `L` command (upload srecord) and `G` command.
  2. Exit cores assembler using `X` command.
  3. Load patch using `L` command (upload patch srecord) and then warm-start cores using the `G` command.

Plain text iconcores-patch.txt

 

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Source for cores-patch

Here is the source for the preceding co-res patch (which can be assembled with the co-res assembler itself). I had to recreate it, as I had lost the original file.

Plain text iconcores-patch.asm_.txt

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