From that part code on the ZIP memory there, it appears to be an M5M41000 which is a 1mbit x1 memory chip.
https://www.datasheetarchive.com/datasheet/M5 … 1&term=m5m41000

There's 32 of them so you have a 32MB FPM SIMM there, pretty rare I think? They're using 32 to get it to the full 32-bits that the 72-pin SIMM uses.

That's a really cool module 😀

Thermalwrong wrote on 2025-08-28, 13:54:

From that part code on the ZIP memory there, it appears to be an M5M41000 which is a 1mbit x1 memory chip.
https://www.datasheetarchive.com/datasheet/M5 … 1&term=m5m41000

There's 32 of them so you have a 32MB FPM SIMM there, pretty rare I think? They're using 32 to get it to the full 32-bits that the 72-pin SIMM uses.

Cool

Thermalwrong wrote on 2025-08-28, 13:54:

From that part code on the ZIP memory there, it appears to be an M5M41000 which is a 1mbit x1 memory chip.
https://www.datasheetarchive.com/datasheet/M5 … 1&term=m5m41000

There's 32 of them so you have a 32MB FPM SIMM there, pretty rare I think? They're using 32 to get it to the full 32-bits that the 72-pin SIMM uses.

i can't find one to sell anywhere. it could have a expensive value. Which system could accept that ? my 486 vlb dont detect it, dont boot with it.

And another one... https://www-crashcomputer-com-br.translate.go … &_x_tr_pto=wapp

renejr902 wrote on 2025-08-28, 14:08:

Which system could accept that ? my 486 vlb dont detect it, dont boot with it.

A 486 system is supposed to work with a module like that. It should behave like a standard 4MB PS/2 SIMM, possibly slightly slower due to the extra buffering chips.

EDIT: Oops, does it say "-10" at the end of the model number of the ZIP chip? That would be a 100ns chips, which is too slow for 486 systems, at least at FSB33. You might try to lower the FSB to 20 or 25MHz to check whether the module is detected that way.

mkarcher wrote on 2025-08-28, 18:15:

renejr902 wrote on 2025-08-28, 14:08:

Which system could accept that ? my 486 vlb dont detect it, dont boot with it.

A 486 system is supposed to work with a module like that. It should behave like a standard 4MB PS/2 SIMM, possibly slightly slower due to the extra buffering chips.

EDIT: Oops, does it say "-10" at the end of the model number of the ZIP chip? That would be a 100ns chips, which is too slow for 486 systems, at least at FSB33. You might try to lower the FSB to 20 or 25MHz to check whether the module is detected that way.

I think it's -70 per the label on the back

Either way, is there any advantage other than possibly cost to build a 72-pin SIMM like this? Is it analogous to 9 vs. 3 chip 30-pin SIMM, and in (C) 1995 per the board wouldn't 4MB, 72-pin SIMMs be down to commodity pricing?

edit: could there have been some other device like laser printers that took 72-pin SIMMs, but had the same refresh issue as 9 vs. 3 chip?

Possibly space limitations, if the motherboard (or whatever thing used it) only had a single slot for memory.
With that many chips, it could be a load issue for the driver of the memory bus, if you had multiple sticks.

Hardware RAID controller cache buffer.

Etc.

Some bespoke slot with enough voltage, and need for specific timings, where you can expect them to not be crowded together.

i will try to get it working

jakethompson1 wrote on 2025-08-28, 18:26:

I think it's -70 per the label on the back […]
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mkarcher wrote on 2025-08-28, 18:15:

renejr902 wrote on 2025-08-28, 14:08:

Which system could accept that ? my 486 vlb dont detect it, dont boot with it.

A 486 system is supposed to work with a module like that. It should behave like a standard 4MB PS/2 SIMM, possibly slightly slower due to the extra buffering chips.

EDIT: Oops, does it say "-10" at the end of the model number of the ZIP chip? That would be a 100ns chips, which is too slow for 486 systems, at least at FSB33. You might try to lower the FSB to 20 or 25MHz to check whether the module is detected that way.

I think it's -70 per the label on the back

Either way, is there any advantage other than possibly cost to build a 72-pin SIMM like this? Is it analogous to 9 vs. 3 chip 30-pin SIMM, and in (C) 1995 per the board wouldn't 4MB, 72-pin SIMMs be down to commodity pricing?

edit: could there have been some other device like laser printers that took 72-pin SIMMs, but had the same refresh issue as 9 vs. 3 chip?

Zip chips were always a strange expensive high end device used to save space installed individually inside old 80’s computers that needed lots of low density memory chips or used in the late 80’s / early 90’s as video memory.

Using low density zip chips on a 72 pin simm in 1995 smells of a high end upgrade for a legacy machine like a late 80’s early 90’s server that theoretically could accept 32mb but never had modules when current or to simply use up old stock as a module like that would be more at home in 1990 as a $5000 part than 1995.

And no 4mb we’re not really commoditized in 1995, ram was bloody expensive alongside the release of memory hungry windows 95, so a pair of more expensive than you would want 4mb SIMMs was still a common system configuration.

32mb of coarse existed but really weren’t common until 1998

rmay635703 wrote on 2025-08-30, 07:42:

And no 4mb we’re not really commoditized in 1995, ram was bloody expensive alongside the release of memory hungry windows 95, so a pair of more expensive than you would want 4mb SIMMs was still a common system configuration.

That makes sense; 8mb worth of 72-pin FPM would still be state of the art on those pre-Triton systems that would be selling then. Perhaps I was thinking of 30-pin 1 meg.