Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!wasatch!cs.utexas.edu!tut.cis.ohio-state.edu!rutgers!bellcore!faline!thumper!ulysses!mhuxo!mhuxu!alux2!smh
From: smh@alux2.ATT.COM (S. Henning)
Newsgroups: comp.sys.mac
Subject: Re: Confused about SIMMs
Summary: dips, chips, and gull-wings
Message-ID: <316@alux2.ATT.COM>
Date: 14 Apr 89 15:13:53 GMT
References: <195@xochitl.UUCP> <72@nisca.ircc.ohio-state.edu>
Reply-To: smh@alux2.UUCP (S. Henning)
Distribution: na
Organization: Laboratory 5217
Lines: 29

In article <72@nisca.ircc.ohio-state.edu> (Bob DeBula) writes:
: 
: High profile SIMMs generally contain standard 1 Mb (or 256K as the case may
: be) DRAM chips soldered to the SIMM board.
           ^^^^^ read DIPS not CHIPS.

: Low profile SIMMs generally contain the itty-bitty "surface mount" chips.
                                             Read PACKAGES not CHIPS ^^^^^

Also know that the CMOS chips run much cooler and avoid the need for special
power supply considerations and special cooling.

A SIMM with CMOS chips in surface mount packages (low profile) is the
only configuration that is compatible with all Mac options.  Any other
configuration requires certain restrictions.

By the way, the chip is a piece of semiconductor that is in a DIP or
surface mount package. A DIP is a dual-inline-package with leads that
are soldered through holes in the SIMM, and a surface mount package is
a very small package with J-shaped leads that are soldered on the
surface of the SIMM.  Some surface mount packages are called J-leaded
and the J curves away from the package and others are called gull-winged
and the J curves under the package.  All the ones I have seen on SIMMs
are gull-winged.  Also, surface mount packages have leads on all 4 sides
while DIPS only have leads on 2 sides.

Cheers,
Steve Henning, AT&T Bell Labs, Reading, PA           UUCP: att!alux2!smh
****                    Lang May Your Lum Reek                      ****