Whoops, I did it again! VIC-20 on the way...

[rubber_jonnie]

Hmm, interesting:

IMG_20220216_142552.jpg

Very nice work here, I suspect it's factory, but don't know enough to say what it's for. I'm guessing to replace missing or bad tracks on this version of mobo.

[stephen_usher]

Seems to be using a few unused OR and NOT gates on the '02 and '04.

I can't see any references to those bodges on-line.

[rubber_jonnie]

Seems to be using a few unused OR and NOT gates on the '02 and '04.

I can't see any references to those bodges on-line.

It does seem to be, yes. Will have a look later too, see if I can find anything, Makes you wonder if some tracks were missed out.

[stephen_usher]

I think I have an answer...

From what I've just read Commodore used larger RAM chips than was required as they had an over-stock, so I think this mod is trying to use the upper half of the RAM chips as a memory expansion. However, this was from Stack Exchange so it's probably wrong.

[rubber_jonnie]

I think I have an answer...

From what I've just read Commodore used larger RAM chips than was required as they had an over-stock, so I think this mod is trying to use the upper half of the RAM chips as a memory expansion. However, this was from Stack Exchange so it's probably wrong.

Interesting. I'm seeing only 3.5KB so it isn't using anything extra, or at least showing anything extra. Will dig more after work :)

[stephen_usher]

Can the VIC=20 basic see more than that? I don't think that it can.

[stephen_usher]

I've just posted that picture elsewhere to see if they know what the mod is.

[rubber_jonnie]

Can the VIC=20 basic see more than that? I don't think that it can.

It can be expanded via the cartridge slot to 32KB from what I've read, though I will be looking at other internal options.

[rubber_jonnie]

I've just posted that picture elsewhere to see if they know what the mod is.

Cool thanks. I did the same.

[stephen_usher]

Looks similar to this: http://www.sdiy.org/richardc64/vic20/vic01.html