At 11:20 PM -0500 2/17/03, gabriel rosenkoetter wrote:
>On Tue, Feb 18, 2003 at 02:10:32AM +0100, Lo'oRiS il Kabukimono wrote:
>  > PAL simms???
>
>Don't recall what the acronym means, but it's a specific format for
>the SIMM.

The original Mac II was built before JEDEC had completely 
standardized high-density SIMM's.  Consequently there is a particular 
combination of RAS/CAS/address signals that triggers a test mode on 
newer SIMM's which the Mac II generates by accident, sometimes.  When 
it does the machine crashes if it has some of the new SIMM's 
installed.  A few SIMM's were built which had a PAL added to the 
standard memory chips to catch the condition and block it from the 
memory.  These SIMM's are specific to the Mac market and therefore 
both rare and (at the time) more expensive.

Only the Mac II needed them AFAICR.
-- 
The opinions expressed in this message are mine,
not those of Caltech, JPL, NASA, or the US Government.
Henry.B.Hotz@jpl.nasa.gov, or hbhotz@oxy.edu