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Update README.md: Formatting

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tomcw 2017-04-21 22:21:14 +01:00
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@ -8,25 +8,22 @@ So as a little R&D proj, I thought I'd convert Dave Rogers' Spectrum
128 Cybernoid routine (written in 1988).
Here's a summary of how I did it:
. I got cybernoid.ay from
http://www.worldofspectrum.org/projectay/gdmusic.htm
. Split it into bin's with AYSplitR
. Disassembled with Inkland's dz80w (http://www.inkland.org.uk/dz80/index.htm)
. I wrote 6502 macros to replace the z80 opcodes
. For cybernoid, I hand converted the z80 code to 6502 (using the
macros)
. I added a few extension to AppleWin's debugger to help debug the 6502
code (ACME symbol loading & ZP pointer support).
- I got cybernoid.ay from (here)[http://www.worldofspectrum.org/projectay/gdmusic.htm]
- Split it into bin's with AYSplitR
- Disassembled with Inkland's dz80w (here)[http://www.inkland.org.uk/dz80/index.htm]
- I wrote 6502 macros to replace the z80 opcodes
- For cybernoid, I hand converted the z80 code to 6502 (using the macros)
- I added a few extension to AppleWin's debugger to help debug the 6502 code (ACME symbol loading & ZP pointer support).
I use Skyfox's MB detection routine.
The Z80 regs are emulated with zero-page memory locations $F0..$F8
The playback routine is very inefficient, as it:
. saves the ZP memory
. restores the Z80 regs
. runs the IRQ handler
. saves the Z80 regs
. restores the ZP memory
- saves the ZP memory
- restores the Z80 regs
- runs the IRQ handler
- saves the Z80 regs
- restores the ZP memory
This allows playback to work simultaneously with Applesoft & ProDOS. If
DOS3.3 doesn't disable IRQs around disk I/O, then it won't work on a