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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: yaqube on May 04, 2008, 11:56:20 AM
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Hello guys,
Now I'm working on improving Minimig's compatibility with games that don't work with currently released firmware. So far some work has been done and some games load now (although not all work correctly - there are still some sprite engine issues which will be solved later, i.e. Alien Breed or Super Frog: main character sprite is currently invisible or corrupted).
During my research I've found a game (Prince of Persia) which uses different mfm disk sync word ($4891 instead of $4489). This information isn't preserved within adf disk image file. I'm looking for similar games to check my firmare solution if it works also with other such games.
The game I'm looking for is the one with following symptom:
- the disk activity LED is still switched on (not blinking)
- and the Minimig doesn't respond to the F12 key or the Menu button.
If you have ever encountered such a game please report it to me. It will be helpful for further development.
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Have a look at:
http://www.opencircuits.com/Minimig_Discimage_support
http://en.wikipedia.org/wiki/MFM
http://de.wikipedia.org/wiki/Bild:FM-MFM-Codierung.png
One way to store non-compliant disc is to just put all the raw MFM bits as a long string of bits. That should allow most disc formats to be stored.
Approaches are sequence of:
* Packets specifying length and "1" or "0".
* Bits as in the MFM (http://de.wikipedia.org/wiki/Bild:FM-MFM-Codierung.png) code.
* Demodulated bits (see first line in the above picture link).
* MFM-Decoded bits as in ADF (which doesn't work.. ;) )
As the program space and processing capacity in the MCU is limited. It might be an idea to let the MCU simply shuffle the bits without processing them. And implement the different decoding schemes in the FPGA.
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freqmax wrote:
Have a look at:
http://www.opencircuits.com/Minimig_Discimage_support
http://en.wikipedia.org/wiki/MFM
http://de.wikipedia.org/wiki/Bild:FM-MFM-Codierung.png
One way to store non-compliant disc is to just put all the raw MFM bits as a long string of bits. That should allow most disc formats to be stored.
The raw MFM code would be twice the size of the ADF! But perhaps someone could write a raw bit reader for the Amiga and create a new format, for them that the minimig could use for difficult games.
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@yaqube,
Is there a site where your work on the MiniMig is available for others to download?
Are you still working on ECS implementation for MiniMig and have you done any work on 60Hz NTSC display for MiniMig?
Forgive me if these questions have already been answered in the past, I missed any answers given.
Thanks for improving the MiniMig with your work.