🚀 go-pugleaf

Andrew Watts <Andrew.Watts@tba.gov.uk> wrote:

> We have just added a 16MB Ram chip to an LCIII.  On reboot the LC does its
> usual 'dong' note, and then proceeds to do 4 chimes going up in scale,
> followed by four notes going down in scale.  The screen remains black and
> the mac does not go any further.
> 
> Removing the chip and putting back the 8MB chip that was there enables the
> mac to start up ok.  This is the second 16MB chip we have tried so I do not
> think it is a faulty chip.

I'm going to pick nits again - you've got a single-in-line memory module
(SIMM) which is (most likely) made up of 8 dynamic RAM integrated
circuits (IC or chip for short).  It might have 9 chips - the extra one
hold the parity bit for each byte of memory (redundant on virtually all
Macs).  If it's got more than 9 chips, it's best to avoid it (that'd
make it a composite SIMM, which Apple has a bit of a downer on).

> The label on the chip says 16MB SIMM 72pin, 70NS, which I think should work.
> 
> Anyone got any ideas?

Well, some months ago I bought a 16MB SIMM - 72 pin, 70ns, 5V, for my
Performa 475 (very similar beastie to an LCIII).  It didn't work - same
symptoms as you describe.  I took it back to the shop, and they asked me
`Is it going in a 486 or Pentium motherboard'.  After the stunned
silence when I said `neither' - `What, you've got a 386?' `No, a 68040'
(etc), they explained they'd had a lot of trouble with that particular
SIMM which worked fine in Pentium boards but not in a lot of 486 boards
- they tested the SIMM in a Pentium PC while I was there, and it worked
perfectly; and then in a 486 PC which didn't like it at all.  They could
offer no explanation of *why* this happened, but replaced my SIMM with a
different one that they said ought to work, and it did.

Rowland.

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