another_808286 wrote on 2024-06-18, 17:39:

Does anybody know anything about these cards or what their original purpose may have been? I am especially curious about the second one that has FPGAs on it.

Stricly speaking, these chips are PLDs not FPGAs. The distinction is a bit hazy but the main point is the PLDs don't have as many internal logic resources as FPGAs do. They serve more basic functions like address decoding and bus interfacing - like what they do on these ISA cards. The second card doesn't need as much help with this so there're just GALs there.

My point being these chips can sort of tell you how many of these cards were made. PLDs are sometimes used in products that are mass produced but you want to avoid it, not even because of the cost but it's a problem for the production line to get all these programmed and tested. PLDs in sockets are even less desirable, although that does give you some flexibility (can be inserted post-production). If the TQFP chips are floppy controllers then this could've been either a custom system to interface non-PC floppy drives to a PC, or perhaps some part of a floppy duplication system - for software distribution. Big enough operation that it required more than 2 drives and possibly parallel writing capability, but not so bit that you'd need to buy some expensive machine to do it. That's my guess.

Deunan wrote on 2024-06-18, 19:19:

another_808286 wrote on 2024-06-18, 17:39:

Does anybody know anything about these cards or what their original purpose may have been? I am especially curious about the second one that has FPGAs on it.

Stricly speaking, these chips are PLDs not FPGAs. The distinction is a bit hazy but the main point is the PLDs don't have as many internal logic resources as FPGAs do. They serve more basic functions like address decoding and bus interfacing - like what they do on these ISA cards. The second card doesn't need as much help with this so there're just GALs there.

My point being these chips can sort of tell you how many of these cards were made. PLDs are sometimes used in products that are mass produced but you want to avoid it, not even because of the cost but it's a problem for the production line to get all these programmed and tested. PLDs in sockets are even less desirable, although that does give you some flexibility (can be inserted post-production). If the TQFP chips are floppy controllers then this could've been either a custom system to interface non-PC floppy drives to a PC, or perhaps some part of a floppy duplication system - for software distribution. Big enough operation that it required more than 2 drives and possibly parallel writing capability, but not so bit that you'd need to buy some expensive machine to do it. That's my guess.

Ok, thanks for the clarification on the chips. The TQFP chips are the actual FDCs I did a bit more research and according to the datasheet, they have integrated tape-drive support and "Perpendicular Recording Support for 4 MB Drives" not sure if these were just common features of all FDCs of the time, but if not then maybe this card is for controlling floppy-connected tape drives? At some point, I may try to just use them as a normal fdc in an old PC to see if that works, maybe they could be used as somewhat normal FDCs. it is off that the one with the PLDs does not have offer the same configuration jumpers as the one without.

These cards came from a school, so I doubt they would have been running a software distribution system there.

Also, I looked a little more at the Allegro II and it does seem pretty low volume. The resistor pack in between the two FDCs is in a socket that has rather sloppily been cut from a longer line of pins (some of the plastic is missing) and it almost looks like the resistor pack itself was cut down from a larger one. Also, the serial number being ALG2-0140 could inmply that this is only the 140th one ever made and since there are only four digits, maybe they only expected to make a few thousand?

The Altera chips are just low capacity CPLDs, doing stuff like address decode as mentioned previously. I'm presonally quite fond of those chips, very nice to make 5V compatible things with ~