SUMMARY: Ultra 5 Memory

From: Burak Baysal (
Date: Fri Jun 12 1998 - 00:54:23 CDT

Ok, I think it is about time I posted a summary.
thanks to all the people replied.

My Original question was:

> Got a question about SUN memory (DIMMs). Are they compatible with the
> regular PC DIMMs? It is physically different, the notches are a
> little skewed, but are there any architectural inconsistencies? The
> same goes with the SPARCStation 5, I think they have the same
> type of memory with the Ultra 5, right? Since Sun has priced
> 64 Meg Ultra 5 memory kit as $395 (~$240 for edu.) and the PC
> DIMMs cost only ~$100 (~$140 for PC-100) for the same size,
> intuition tells me that there must be a difference. but then again
> it has failed me more than once.
> the Ultra 5/10 service manual sez:
> C.1.4..Memory Architecture
> The memory architecture uses the 168-pin JEDEC standard extended
> data out (EDO) 3.3-Vdc buffered DIMMs.
> .
> .
> .
> C.1.4.2..DIMMs
> The DIMMs used in the system unit have the following characteristics:
> JEDEC standard in 168-pin DIMM
> Support ECC (.72)
> Single 3.3-Vdc +/- 0.3-Vdc power supply
> LVTTL-compatible input and outputs
> All inputs are buffered with exception of RAS_L
> CAS_L before RAS_L refresh capability
> Since the notches are a little skewed, is it really
> JEDEC standard? I looked at some data sheet of PC memory
> I don't see why it wouldn't work if the notches were in the right
> spot.

There is no voltage conflict as couple people mentioned. nor there are
any size problems, other than the obvious different key. the answer
was that Sun uses EDO buffered DIMMs (coming from Chris O'Neal and
Andreas Holzhammer), it also sez in the service manual. PC-Dimms are
appearently SD-Ram.

People advised me to various manufacturers, I contacted venturatech
at and they were quite helpful.

btw, Richard.Dansereau sez:
"...I can definitely say that Ultra 5 DIMMs and SPARCStation 5 memory
are different and are NOT compatible."

so, thanks again to all who took the time to reply.

Burak H. BAYSAL				|	|
Laboratory Manager, Electrical Eng.	||
Southern Ill. Univ. at Edwardsville,	|Voice: (618) 650-2523	|
Campus Box 1801,	IL, 62026	|Fax: (618) 650-3374	|

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