Hey everyone not a big commodore person (no offense) but I have this prototype board from 8250 development looks like they were slimming it down for other computers in their lineup. I don't know much about it or its history but if someone is interested in preserving it or buying it I'd love to give it a new home. But more than anything trying to see what information you all may know or could provide about it. Pictures below.

What makes you conclude it's a prototype? It looks like it has a daughtercard in, but that could just be a repair.

>> ClassicHasClass said:

What makes you conclude it's a prototype? It looks like it has a daughtercard in, but that could just be a repair. Click to expand...

Both looking at the ROM image and the fact that it was discovered internally at Commodore Labs. There were prototype IEEE drives being developed for use in the 720D. Some of the early examples of the boards did in fact have this "8250 Mini" riser board but mine is an earlier variation before some changes were made. It's also worth noting that this would've allowed for dual drives had these have actually come to market and none ever did hence why this is a prototype board. It started and ended in Commodore Labs and never came to fruition.

Did you ever find an answer for this? From what I could find and figure out, the add-on "8250 mini" board adds a second drive to the SFD1001. I have a Commodore 8296D with dual internal floppies using the same drives and the dual floppy controller board doesn't look like this. I also have an 8250LP dual external drive that uses these drives and it's also not the same. That said, I think it was purposely built for a dual SFD1001.

Very cool board.

Santo

I never got any replies but this is a confirmed Commodore prototype, I'd be more than happy to send it off for someone to see if they can get it booting up on loan.

I do have the right drive mechanisms and would be happy to do that but I am in Canada and these days, shipping to me is fine but having something go back to the US is not something I am willing to do until things change. There are more hoops than normal to jump through and I won't do that for your current administration. Sorry about that. I would have had fun trying.

>> snuci said:

I do have the right drive mechanisms and would be happy to do that but I am in Canada and these days, shipping to me is fine but having something go back to the US is not something I am willing to do until things change. There are more hoops than normal to jump through and I won't do that for your current administration. Sorry about that. I would have had fun trying. Click to expand...

I totally understand. I could ship it, what part of Canada are you around i fly to Canada a few times here and there so could pick it up at a later time. Would love to see what this does.

I am in Richmond Hill, just north of Toronto in Ontario. At the moment, we have a postal strike and it's best to ship with USPS. Shipping by courier will incur Border entry fees even if the item has no value. and that adds complexity. Let's hold off for now but I definitely want to try it at some point.

Hopefully, it's all there. The chips missing on the bottom board look to have been transferred to the daughterboard but the one chip missing on that might be an issue. Do you have the ability to read the 2716 on the daughterboard? I can compare it to the contents of what is normally on that EPROM to see if it's different. Hopefully the "x" doesn't mean it's bad.

I can read it, I'll get that file uploaded shortly.

>> snuci said:

I am in Richmond Hill, just north of Toronto in Ontario. At the moment, we have a postal strike and it's best to ship with USPS. Shipping by courier will incur Border entry fees even if the item has no value. and that adds complexity. Let's hold off for now but I definitely want to try it at some point. Hopefully, it's all there. The chips missing on the bottom board look to have been transferred to the daughterboard but the one chip missing on that might be an issue. Do you have the ability to read the 2716 on the daughterboard? I can compare it to the contents of what is normally on that EPROM to see if it's different. Hopefully the "x" doesn't mean it's bad. Click to expand...

Here you are @snuci.

Sadly, the first half of that 2716 EPROM is either empty or not read properly. 0x0000-0x3FF is all FFs. 0x400-0x7FF is similar to the second half of 251257-02A but not exactly. Makes it interesting. Hopefully the EPROM is not messed up or the 8250 Mini board will not work.

EDIT: Never mind. A friend had a copy and it matches your EPROM exactly.; even with the first half all FFs Very interesting.

I also tried to re-dump the .bin again. I've attached it below looks like slight difference this time.