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The project is mainly about converting Msx1/ColecoVision games, firstly the
16k ones (seems more easy to convert), and so the others when those 16k were
'easily' converted.

ColecoVision can be a next step of the project - coleco seems to have a
hardware very close to Msx1 (when playing the same games as Cabbage Patch
Kids and Rock-N-Bolt you can bet are the same hardware) - maybe differences
between Coleco and Msx1 are as i/o and bios addresses and so on. Processors
(cpu, video and sound) seems to be exactly the same.

Difficulties:

- Msx1 games normally calls MsxBios routines (like LdirMv and others), which
  means some of those has to be rewritten on ZxSpectrum
- reallocate all game data starting at 0x8000 instead of 0x4000
- the main code is always ready, seems to just needed to be patched (?)
- the msx1 hardware sprite issue (have to be simulated as is on almost whole
  of zx games)
- another sprite issue - normally Konami sprites are overlapped and stagered
  (trying to avoid the 1 colour sprite limitation on Msx1) - maybe that can be
  a real problem - the code of Msx1 games seems to manage a couple of sprites
  only for just one figure element, when you just need 1 on ZxSpectrum. 
- scroll speed - msx1 can manage 'graphics-mode' (screen2) as 'text-mode',
  which provides a very faster scroll (1/16 of the time, or 1/9 (comparing
  with ZxSpectrum) - some ZxSpectrum games are very looking like this scroll
  one (like on Perico Delgado and Tour de Force)
- on Msx1 sprites you just have to set their coordinates, and on ZxSpectrum
  you really have to redraw all that on screen. (the main problem would be
  only speed and screen refresh, colour attribute noise seems to be a minor
  problem)
- pokes on video memory are via i/o commands (or bios routines would call
  those), not ld or some others. Msx1 video memory has it own processor, and
  z80 can't directly access that as ZxSpectrum can
- ZxSpectrum (extended on 48k models?) seems to use the same sound board as
  Msx1 uses. 
- colours are not exactly the same but can be somehow close (as playing
  performance wouldn't be a further problem)

I think that's all for now

Paulo
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