On May 28, 2010, at 7:42 PM, tortoise wrote:
A Pismo will accept 2 x 512 MB of "low-density" RAM for a total of
1024 MB (1 GB). The thicks may be either "low-profie" or "high-
profile" or both in any combination.
I thought that the lower slot on the pismo was picky in regards to the
512 cards in the actual physical fit of the card that some interfere
with it all going back together properly ? It seems there has been
discussion of that here in the past. That's partly why I didn't
upgrade mine -- can't use generic cards.
The issue is Apple relied on an early specification for the maximum-
sized stick, and then it went and put some ICs where they thought
would not interfere with the complete seating of the sticks.
This proved to be overly optimistic, and there are a number of JEDEC-
approved sticks which will not work in the Wallstreet through Pismo
PowerBooks on account of this interference.
Installing so-called "high-density" RAM in these machines will often
result in the stick being read as one-half capacity.
I've seen this happen in my beige g3 also, I didn't know why, but
again its lower on RAM than it should be
(only 192 and its running Jaguar still)
There is a fundamental flaw in the early G3 DRAM controller
design ... not enough addressing lines and/or lines which are not
multiplexed properly for all JEDEC-approved conditions.
It cannot properly handle every JEDEC-approved stick, only a subset
of these.
Those in the early G3 families (Wallstreet, Lombard and Beige) cannot
handle 512 MB sticks at all, and, indeed, these cannot handle "high-
density" sticks at all.
Those in the late G3 family (Pismo) can handle 512 MB sticks in both
slots, but it must be "low-density".
The so-called "first G3 PowerBook" (AKA, 3500/"Kanga") had additional
issues related to address lines and multiplexing, which is why there
is an Apple-branded 3400-only 128 MB card, an Apple-branded 3500-only
128 MB card and a third-party-branded combo 3400 and 3500 128 MB
card. There are also third-party-branded 3400-only 128 MB cards.
The 3500 was sold only one way: with 32 MB of on-mobo soldered RAM
and a 3500-only 128 MB card, for a total of 160 MB, and these models
have an absolute maximum capacity of 160 MB.
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