Article Created: 18 July 1995 Article Review/Updated: 8 August 1995
TOPIC
The following is a list of common questions and answers (Q&A) concerning the new type of RAM, DIMMs (Dual Inline Memory Modules) used in the Power Macintosh 9500 series computers.
DISCUSSION
QUESTION: How many SIMM (Single Inline Memory Module) slots are available in the Power Macintosh 9500 computers?
ANSWER: There are no SIMM slots in the Power Macintosh 9500 computers. Memory expansions slots on the Power Macintosh 9500 are called DIMM slots, not SIMMs. There are 12 DIMM slots total in the Power Macintosh 9500.
QUESTION: Is the 16 MB standard configuration of these computers using up any slots or is the RAM soldered onto the logic board?
ANSWER: The Power Macintosh 9500 series computers come standard with 16 MB of memory. Since there is no memory soldered on to the logic board we currently configure the system with either two 8 MB DIMMs or one 16 MB DIMM depending on availability.
QUESTION: Does memory (DIMMs) have to be installed in pairs?
ANSWER: Unlike the original Power Macintosh computers, the Power Macintosh 9500 DIMMs do not have to be installed in pairs. However, if you intend to take advantage of the increase in performance that memory interleaving offers, you will need to install the DIMMs in identical pairs. Refer to the "Power Macintosh 9500 Technical Information" booklet that is included with the Power Macintosh 9500 series computers for additional information on which DIMM slots to use to take advantage of memory interleaving. With memory interleaving you can see up to an 8% increase in performance depending on various factors including the applications being used.
One of the main reasons that the SIMMs had to be installed in pairs on the original Power Macs is that the 72-pin SIMMs used in the original Power Macintosh computers were 32-bit wide SIMMs, however, the data buses of the Power Macintosh computers prior to the 9500 series are 64-bits wide. Thus you had to install two SIMMs to accommodate the 64-bit wide data bus.
The Power Macintosh 9500 on the other hand uses 168 pin, 70ns or faster DIMMs which are 64-bit wide. Therefore it only takes one DIMM to meet the 64 bit wide data bus requirement and thus you only have to install one DIMM at a time.
Article Change History: 08 Aug 1995 - Added information about size of DIMMs included. 28 Jul 1995 - Added explanation on number of DIMM slots
Support Information Services Copyright 1995, Apple Computer, Inc.
Keywords: kppc,kpci,supt
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