🚀 go-pugleaf

In article <1067@apple.UUCP> lsr@apple.UUCP (Larry Rosenstein) writes:
>
>The Mac II and new RAM upgrade kits use 120 ns RAM.  The older machines (ie,
>Mac Plus) use 150 ns RAM.  It could be that the recent Mac Pluses also use
>120 ns RAM, which would account for some SIMM modules working and other not.
>
>I think if you examine the RAM chips carefully, you will see an indication
>of their speed.

Dynamic RAMS are a lot like floppy disks in this reguard.  Most of the disks
labled single sided work double sided (it's often cheaper to just have one
assembly line making disks, and those that don't pass inspection are always
single sided, many others happen to be double sided).  Many 150 ns RAMs are
really 120 ns RAMs (in fact, many 200 ns RAMs are really 150 ns RAMs--this
is one of the ways that ATARI cuts costs on the ST--uses 200 ns RAMs at 150 ns
speed).

Larry's explanation might be right, I haven't looked at the latest batch of
Mac Plus SIMMs lately.  But in many cases you'll find that 150 ns RAMs pass
as 120 ns under all but the most thorough tests (the sort of thing that they
go through 1 month after the warranty is over).

So, use 150 ns RAMs in your MacII at your own risk!

Peter
--
Peter "Arrgh" Korn	 			Oh when, oh when will my MacII
korn@ucbvax.Berkeley.EDU				 arrive?  Oh where, oh
{decvax,dual,hplabs,sdcsvax,ulysses}!ucbvax!korn	      where can it be?