VOGONS


First post, by Sidewinder

User metadata
Rank Newbie
Rank
Newbie

An acquaintance found this memory card and shared it in a retro hardware group on Facebook. So far we have not been able to identify what it is for. There is speculation that it is an ide card, but I think it is a cache of something.
What do you think? I googled some info but found only that 74ACT244 is a buffer and KM44C is memory that could be in any other ram module. Could it be a ram module from some old rig? no idea. My knowledge reaches this far.
Thanks in advance.

tB68IWe.jpg
v2fr8Q7.jpg

Reply 1 of 3, by dionb

User metadata
Rank l33t
Rank
l33t

The PCB is pretty clear: this is a 1MB memory module. The 8 256kx4 FP DRAM chips indicate it works with a 32b wide bus, which would correspond to a 386DX or 486 if this were system memory for a PC. 4x 256kx1 chips are for parity, and the 74ACT244 chips are indeed buffers. Essentially this is a 72p buffered FD SIMM with an odd connector. No really new info here.

Now, the form factor is clearly proprietary. I suspect it's Samsung (not only are the chips Samsung too, but "SEC code" sound suspiciously like "Samsung Electronics Corporation" and Made in Korea is another indication). It *could* be system RAM, but the combination of such a low quantity with a 32b wide bus would be odd, no 386 upgrade would just do 1MB, even back in 1991. Video memory might also have been an option for 1MB FP, but I'm not aware of any video solutions using parity memory. So my bet would be on some non-PC solution. Perhaps an upgrade for a laser printer?

Reply 3 of 3, by mkarcher

User metadata
Rank Member
Rank
Member
dionb wrote on 2021-02-02, 07:46:

It *could* be system RAM, but the combination of such a low quantity with a 32b wide bus would be odd, no 386 upgrade would just do 1MB, even back in 1991.

I dont think it is 32bit wide. With parity, that would be 36 pins just for data. The connector is clearly labeled as 40 pin connector, so this doesn't work out. Let's assume it's just x16. In that case, it would be two banks of 256K x 16. That needs

  • 18 data pins (16 actual data + 2 parity)
  • 9 address pins (9 columns * 9 rows makes 256K addressable cells)
  • 2 /RAS pins (one per bank. these pins also work as bank select pin)
  • 1 /CAS pin
  • 1 /WE pin
  • 2 power pins (better something like 3*5V, 3*GND, i.e. 6 power pins)

This results in a minimum pin count of 33 pins, and 37 pins with a sensible amount of power and ground pins. This fits the actual 40 pins quite well. So my money is on 16b wide bus.

Of course, this does not mean the final conclusion that this might be a printer module needs to be wrong. If the printer is 68000 based, it would have a 16 bit bus, and a 16 bit module would fit quite well. 68000 processors were quite common in early laser printers.