Apple comments on 3rd party RAM
Author: from AppleLink
Date: February, 1989
Keywords: memory hardware upgrade SIMM
Text: Many users have asked about the differences between Apple SIMMs and those in other vendors' products -- particularly physical size differences, speed differences and parity checking. Numerous third-party vendors offer SIMMs that seem to work fine in the Macintosh. Although we don't specify the technical requirements of third-party SIMMs, many of those suppliers have either obtained Apple's specification or determined our system requirements, designing their chips accordingly. IBM is another computer manufacturer that is using SIMMs in its PS2s. Some differences are include parity checking, basic configuration and speed. A SIMM that provides for parity checking doesn't exclude that RAM from being used in a Macintosh. Such SIMMs could be used if all other timing and pinouts were compatible, since the Mac will merely ignore that extra line. Apple engineers have experimented with 2 IBM Model 30 256K x 9 SIMMs in a Macintosh Plus, and although the testing has not been extensive, these SIMMs have functioned using routine applications -- Excel, HyperCard and Microsoft Word -- and have passed a short- and extended-memory test. However, just because these SIMMs appear to work doesn't mean that Apple endorses the use of ''IBM'' SIMMs in our systems. IBM suppliers and third-party vendors use differing RAM and designs to meet PS2's requirements, not ours. Another consideration is the height of the board itself: it must not be so tall as to interfere with expansion cards in a Macintosh SE (if any), or the chassis in a Macintosh Plus. However, there ought to be plenty of vertical room in a Macintosh II. (NOTE: Apple LaserWriter SIMMs are physically and electronically incompatible with Macintosh SIMMs.) Copyright 1988 Apple Computer, Inc.
Copyright © february, 1989 by from AppleLink