What is UDRAM?

[tcpf429]

Hi all,
I have recently obtained an IBM Aptiva (I believe it's a 2159) and I'm just basically messing with it-adding hard drives and random ISA cards, etc. But I noticed a unique and puzzling feature. Next to the four 72-pin SIMM memory slots, there is a slot for memory the same size as SDR SDRAM, but with different notching-a typical SDRAM chip won't fit in there (I ended up destroying the latches). The slot has "UDRAM" and "5.0 V" on it. I tried searching these on the Internet, but wound up with nothing to answer what it is or if I can get it. So, does anyone here have a clue?

Thanks!

 

[modem7]

The slot has "UDRAM" and "5.0 V" on it.

UDRAM or VDRAM ?

 

[Old Thrashbarg]

It's probably just for a regular 5V EDO DIMM. The 'U' in UDRAM may be for 'unbuffered', to make the distinction from the buffered type commonly used in Macs at the time.

 

[tcpf429]

UDRAM or VDRAM ?

Pretty sure it is UDRAM, I double-checked

 

[tcpf429]

It's probably just for a regular 5V EDO DIMM. The 'U' in UDRAM may be for 'unbuffered', to make the distinction from the buffered type commonly used in Macs at the time.

'K, but EDO memory doesn't fit in it. Can I get ahold of this memory anywhere for cheap?

 

[g4ugm]

A quick search on the IBM announcement database returns the this:-

http://www-01.ibm.com/common/ssi/Sh...A97-0003/index.html&lang=en&request_locale=en

which says ...

Memory SIMM: 72 pin, 60NS tin lead, fast-page or EDO,
32 or 36 bit
DIMM: 168 pin, 60NS, Gold, EDO or fast page mode,
64 bit

But I not several sites e.g.


http://www.buycomputermemory.com/memory/IBMAptiva2159S78MemoryRAM.html

warn about poor performance with certain memory configurations...

 

[Old Thrashbarg]

'K, but EDO memory doesn't fit in it.

I'm guessing you're associating EDO with 72-pin SIMMs, and of course those won't fit in a DIMM slot... but EDO came in several different form factors, including 168 pin DIMMs.

Where to get 'em cheap, I dunno. The buffered 5V ones are pretty common, and unbuffered 3.3V is pretty easy to get too, but unbuffered 5V is harder to find. (Assuming that's even what the thing takes... remember, I'm just making an educated guess here.) I'd say just skip it and stick to common SIMMs... it's not like there's any real advantage to using a DIMM in this instance anyhow, it's the same memory as what you get with a SIMM, just on different size stick.

 

[tcpf429]

Ok, will do.

Ok, will do.

I'm guessing you're associating EDO with 72-pin SIMMs, and of course those won't fit in a DIMM slot... but EDO came in several different form factors, including 168 pin DIMMs.

Where to get 'em cheap, I dunno. The buffered 5V ones are pretty common, and unbuffered 3.3V is pretty easy to get too, but unbuffered 5V is harder to find. (Assuming that's even what the thing takes... remember, I'm just making an educated guess here.) I'd say just skip it and stick to common SIMMs... it's not like there's any real advantage to using a DIMM in this instance anyhow, it's the same memory as what you get with a SIMM, just on different size stick.

If the Aptiva takes a max of 128 MB's of RAM, then I will just maxing that out with the SIMM's. Anyway, thanks everyone for your time in solving the question!