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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: Caius on February 11, 2008, 07:43:47 PM

Title: 5V and 3.3V SIMMs
Post by: Caius on February 11, 2008, 07:43:47 PM

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).

Title: Re: 5V and 3.3V SIMMs
Post by: DoogUK on February 11, 2008, 08:15:17 PM

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

Title: Re: 5V and 3.3V SIMMs
Post by: delshay on February 12, 2008, 12:05:09 AM

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

Title: Re: 5V and 3.3V SIMMs
Post by: banzai on February 12, 2008, 02:39:54 PM

DoogUK is right. According to Micron (http://download.micron.com/pdf/datasheets/obsolete/modules/DM44_2.pdf), 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

Title: Re: 5V and 3.3V SIMMs
Post by: Caius on February 12, 2008, 03:01:12 PM

@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.

Title: Re: 5V and 3.3V SIMMs
Post by: amiga1260 on February 12, 2008, 03:34:28 PM

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

The Blizzard cards only accept 5 Volt SIMMs.

Title: Re: 5V and 3.3V SIMMs
Post by: Caius on February 13, 2008, 08:19:45 AM

Quote

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.

Title: Re: 5V and 3.3V SIMMs
Post by: lorddef on February 13, 2008, 10:32:49 AM

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.