I/O Interface

[MADrigal]

Sorry I wrote bit 6 but I meant bit 5.

[@username@]

From looking a little deeper today - it seems the ROM is significantly different from the original colecovision.

These offsets are fixed as part of the OS - but line up with the dumped laser.bin

Code: Select all

LASER.BIN
Offset 0x0069 == 0x3C == Country byte (America == 0x3C, Europe/Japan == 0x32)
Offset 0x006A == 0x2BAD - Adjust for stuck bit (AND 0xDFDF) == 0x0B8D == ASCII Character table
Offset 0x006C == 0x2B25 - Adjust for stuck bit (AND 0xDFDF) == 0x0B05 == Number table

NTSC.BIN
Offset 0x0069 == 0x3C
Offset 0x006A == 0x16AB
Offset 0x006C == 0x1623

When comparing these tables, after adjustment, they are the same upper and lower case characters and punctuation!

[MADrigal]

There is an update!
It looks like my friend Mark was able to 'fix' the EPROM and obtain stable dumps of both 4Kb chips.
Let's continue this conversation on the right thread (the one on the Colecovision module).
I have also uploaded the file there - please feel free to download and analyse it. It is Z80 code. Pls don't share the file outside of the forum for the time being - until it is confirmed to be working.
viewtopic.php?p=4466#p4466