Tim wrote
>OK, bear with me. So I have two identical Powerbase 180s; each had 32MB of
>RAM (two 8MB + one 16MB = 32). I decided it was time to upgrade, one
>computer at a time. On my first order, I bought two 32MB EDO DIMMS and
>replaced the two eights. Aside from not booting unless the 16MB (we'll call
>it the Mitsubishi 16) was in the first slot, I got my 32+32+16=80MB. Call
>these two 32s "32 old".
>
>Second order. I bought exactly the same part numbers (although the chips
>that came are from a different manufacturer). The 16MB in the second
>computer is from Cubig, not Mitsubishi. Putting the DIMMS in the same
>positions, I got an indicated 40MB! Switching the two new 32s (call them 32
>new) with the two 32olds I then got 72MB! To summarize:
>
>Config 1: 16Mitsu + 32old + 32old = 80MB
>Config 2: 16Cubig + 32old + 32old = 72MB
>Config 3: 16Mitsu + 32new + 32new = 48MB
>Config 4: 16Cubig + 32new +32New = 40MB
>
>I *know* that both of my 16MB DIMMS are really 16s, because I had a total of
>32MB in each computer before I started. Obviously I will return the new
>32s, and try to get the same brand I got the first time, but that doesn't
>explain why the Cubig 16 plus the two old 32s only yields 72MB. I zapped
>the PRAM on both machines with no change. Thanks in advance,
welll...
three comment first...
-are you using OS 8+ ie do you have the system profiler which shows which
slots have
what size dimms?
-the PowerBase is supposed to be able to recognize a 32mb dimm in the first
slot
-a proper pram zap is from startup rather than restart on PowerPC machines
I remember a ram simm once which had written on it 16mb (32mb EDO)
I suspect a memory controller problem here
Before you send them back, try 3x 32 in the first computer.
also, check out
http://www.chipmunk.nl/DRAM/ChipManufacturers.htm
which lists dimms by manufacturer of the IC's on the stick
to check that all the dimme have are similar (ie EDO, same speed and same
refresh rate.)
A few more tests are in order
2 x 16 to check for 32 mb
8 + 2 x 16 to check for 40 mb
Also...from the http://www.macgurus.com website...
Apple Technical Information Library (TIL) article Power Macintosh
Computers:
-snip-
In the event FPM and EDO memory are mixed in these machines, the
memory controller will address the DIMMs in Fast Paged Mode (FPM).
Interestingly, MacGurus has noted far
better compatibility in these Alchemy variants using 5v EDO rather
than 5v FPM, and strongly recommends its use.
-snip-
1Note: Power Computing Corporation has publicly confirmed that PowerBase
clones require 5v 2k refresh EDO DIMMs with an access speed of 60ns,
although other logic boards
based on the Alchemy specification, like the Performa 5400 & Performa
6400, also accept FPM DIMMs. In fact, PCC goes so far as to state: "The
PowerBase and all Alchemy based
machines require EDO DIMMs. Fast paged mode DIMMs, which are commonly
used on previous machines, will not work."
Cheers...Michael
So...
--
Power Computing is sponsored by <http://lowendmac.com/> and...
123Inkjets.com <http://lowendmac.com/ad/123inkjets.html>
Support Low End Mac <http://lowendmac.com/lists/support.html>
Power Computing list info: <http://lowendmac.com/power/list.html>
Send list messages to: <mailto:[EMAIL PROTECTED]>
To unsubscribe, email: <mailto:[EMAIL PROTECTED]>
For digest mode, email: <mailto:[EMAIL PROTECTED]>
Subscription questions: <mailto:[EMAIL PROTECTED]>
List archive:
<http://www.mail-archive.com/powercomputing%40mail.maclaunch.com/>
Using a Macintosh? Get free email and more at Applelinks!
<http://www.applelinks.com>
