5V and 3.3V SIMMs

[Caius]

I'm about to buy 100 EDO SIMMs for next to nothing. However I don't know if they're all 5V or not. Can I damage my Blizzard 1230IV if I put a 3.3V SIMM into it? Also, is there any way I can tell if a SIMM is 5V or 3.3V? They don't generally seem to be marked as such (or I just don't know where to look).

[DoogUK]

Well to say the least 3.3v simms are very rare, more often they were dimms for early ppc macs.

[delshay]

3.3v simms normally have a regulator. check the manufacture for comformation.

[banzai]

DoogUK is right. According to Micron, these SIMMs only came as 5V units. If there were any 3.3V models made, they were proprietary, and not common (I've never seen one, but I have seen 32-pin SIMMs!).

The Micron pdf linked above should give you enough info to figure out what you've got. I usually look at the individual chips on the board, and go from there. If you see eight xx44256-80 chips on there, then every two chips gives you 256Kx8, four gets 256x16, and you wind up with 256x32 counting all eight. Divide this by four to get 8 bit-wide, which means you multiply by four to get the memory count (32b/4=8, 256Kbx4=1024K). So, that SIMM would be a 1M SIMM.

Most chips are marked similarly, with xx#1#### meaning "by 1 bit", and xx#4#### meaning "by 4 bit". The last numbers indicate the capacity, usually 256, 512, 1024, etc. The number after the hyphen is the speed, in nano seconds, a "-80" or "-8" meaning 80nS.

Hope this helps...

banzai

[Caius]

@banzai
That's good info, thanks!

For the record, I've come across 3.3V 72pin simms several times in my searches. Often for IBM servers, so proprietary, yes.

[amiga1260]

Years ago I asked DCE about The Blizzard 1260 SIMM Voltage.

The Blizzard cards only accept 5 Volt SIMMs.

[Caius]

amiga1260 wrote:
Years ago I asked DCE about The Blizzard 1260 SIMM Voltage.

The Blizzard cards only accept 5 Volt SIMMs.

You contacted them and actually got an answer? Wow, that must be one in a million. I tried contacting them myself a few times in the old days, never received an answer. I also know several other people who never was able to get in touch with DCE.

[lorddef]

I've got a Cobalt Qube2 that's supposed to only take 3.3v simms, however it seems to work fine with 5v ones too.