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Space Invaders Deluxe Roklan version.

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Roklan was working on an official conversion back then.  I found a prototype but I can’t get it to work. 

F2E3DA85-926A-45C5-9FC6-ACCA4663872F.jpeg

5626AA1C-293E-4893-82D8-98C40DEC40AF.jpeg

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30 minutes ago, Dutchman2000 said:

Roklan was working on an official conversion back then.  I found a prototype but I can’t get it to work. 

F2E3DA85-926A-45C5-9FC6-ACCA4663872F.jpeg

5626AA1C-293E-4893-82D8-98C40DEC40AF.jpeg

Maybe "compile" them into one 16k chip!

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23 hours ago, SoundGammon said:

Maybe "compile" them into one 16k chip!

Tried that, didn’t work.  

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Just now, SoundGammon said:

Maybe it's the 8-bit version.

Nope, found on a 5200 board in a 5200 case. 

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On 3/10/2021 at 8:04 PM, Dutchman2000 said:

Nope, found on a 5200 board in a 5200 case. 

 

Is it known who at Rocklan was working on the official conversion?

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On 3/26/2021 at 12:13 PM, Lynxpro said:

 

Is it known who at Rocklan was working on the official conversion?

No, it is not known who was working on it. 

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Bump.  Has anyone looked into this?  How close is the code to the 8-bit version?

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Posted (edited)

This is unlikely to work. The dumps seem to be correct, but there is a lot of unused space in them. The 8-bit version is 8K in size. These 3 chips contain only about 4K of data.

 

The HI chip is mostly empty, except for the init vectors at the end, so it should be mapped to $B000-$BFFF.

The LO-MID chip is fully filled, while the HI-MID chip only contains data in the first $50 bytes. I believe this is correct though - when joined together, LO-MID and HI-MID matchthe last ca. 4K of the 8-bit version. It seems that LO-MID should be mapped to$7000-$7FFF and HI-MID to $8000-$8FFF.

 

The issue is, there is no data on the chips that would match the first 4K of the 8-bit version. The init vector points to $6047, which means that the missing 4K should be mapped to $6000-$6FFF.

 

Overall, this cartridge seems to use the "Two chip 16 KB 5200 cartridge" mapping. The ROM image should be formed by joining the missing 4K, LO-MID, HI-MID and HI in that order, to form the following memory mapping:

???    -> $4000-$4FFF, $6000-$6FFF
LO_MID -> $5000-$5FFF, $7000-$7FFF
HI_MID -> $8000-$8FFF, $9000-$9FFF
HI     -> $A000-$AFFF, $B000-$BFFF

 

Edited by Kr0tki

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Thanks for confirming.  I guess we need to find that missing chip.  Sounds like the game was going to be the same as the 8-bit version though.

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I don't know much about ROM reading, but is it possible that LO-MID is in fact an 8K chip that was dumped as a 4K one?

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On 7/11/2021 at 11:32 AM, Kr0tki said:

I don't know much about ROM reading, but is it possible that LO-MID is in fact an 8K chip that was dumped as a 4K one?

Wouldn't they all have to be the same size?

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Not necessarily - it depends on the wiring of the cartridge PCB. I suppose that for prototyping they might have been using PCB's that are universal, i.e. accept either 4K or 8K chips in the sockets.

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The chips were found on a standard Atari made 5200 board.  The chips were read correctly and are in fact the correct size.

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I thought so.  So one is missing then.  Bummer

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