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 Post subject: ROM identification
PostPosted: Sun Jun 03, 2007 7:20 am 
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Joined: Sun Jun 03, 2007 6:43 am
Posts: 130
Location: Rethan Manor, Balmora, Hlaalu District
As you probably know, there is an identification scheme in place with the "official" Retro Replay ROMs that the "official" Cyberpunx Flash-Util utilizes to display information about the ROM you are about to flash.

The identification method has not been documented anywhere, so I bugged CountZero about it. A long time went without an answer to my email, but then I managed to ambush him on IRC and gained the information.

I will share it with you now here. I also learned from C0 that he does not read his emails - just to let you know. This appears to be true for Mr. Aachten as well, because I had to do the same with him to request a BIOS feature.

Okay, here is the deal. The identification is 128 bytes into the image, at $8080 in memory when the first ROM window is selected. It starts with "RR" and is followed by 3 bytes in normal ASCII for version information.

Then, a free form text string of 16 bytes length follows. This is intended to give the name of the ROM. The "official" ROMs actually have an author attribution there instead. Here is the whole thing:

Code:
index    content

$80-$81  ID tag, literal "RR" or $52 $52
$82      major version number
$83      minor version number
$84      revision (letter or second digit)
$85-$94  string for name (16 bytes)


The numbers are stored as their ASCII values, for example "38B", so it can actually be interpreted as a string as well. Finally, here is a dump (yes, it is actually called that) from the RR ROM version 3.8B using my hextype utility:

Code:
Printing rr38bpal.bin from $000080 to $00009F:

000080: 52 52 33 38 42 2D 43 4F 55 4E 54 20 5A 45 52 4F   RR38B-COUNT ZERO
000090: 2F 43 50 58 2D BD 00 42 30 01 00 00 00 00 00 00   /CPX-..B0.......


Hope this is of use to my fellow RR ROM hackers. :D

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Commodore 128 Programmer
City of Kouvola, Finland

http://mydarkgothvampiricplace.endofthe ... Commodore/


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PostPosted: Sun Jun 03, 2007 10:56 pm 
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Joined: Wed Jan 11, 2006 12:22 pm
Posts: 860
Great info!

*Thumbs up*


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