TITLE
    Macintosh Quadra 900 and 950: Layout of SIMM Banks
Article ID:
Created:
Modified: 		10632
8/20/92
9/17/92
TOPIC


    This article discusses the layout of the Macintosh Quadra 900 and 950 SIMM
    banks and provides memory configuration and dynamic RAM (DRAM) information.

DISCUSSION


    The layout of the DRAM SIMM banks for Macintosh Quadra 900 and 950 differs
    from other Macintosh models, which are aligned vertically. The Macintosh
    Quadra 900 and 950 have four SIMM banks that are aligned horizontally with
    two slots on the left and two slots on the right as shown in this diagram.


    Back
    ----------------------------------------


    |---------- Bank ----------|
    |---------- D ----------|

    |---------- Bank ----------|
    |---------- C ----------|

    |---------- Bank ----------|
    |---------- B ----------|

    |---------- Bank ----------|
    |---------- A ----------|


    ----------------------------------------
    Front


    * The Macintosh Quadra 900 and 950 accept standard 1MB or 4MB SIMMs rated
    at 80 ns or faster. Although acceptable, there is no speed improvement
    when using RAM rated faster than 80 ns because the memory control
    unit (MCU) is programmed for 80 ns RAM.

    * Each slot in a given bank must be either empty OR fully populated with
    four SIMMs of the same size and same speed. If a bank is either not
    empty or not fully populated with SIMMs of the same size, you will hear
    chimes at startup, indicating a hardware failure.

    * Apple's documentation states that all filled banks must use SIMMs of the
    same speed. You cannot mix RAM SIMMs of different speeds, even between
    banks.

    * Each bank is independent; therefore, you can populate the banks in any
    order. For example, four 1MB SIMMs in bank B and four 4MB SIMMs in
    bank D is an acceptable configuration.

    * The available memory configurations for the Macintosh Quadra 900 and 950
    are 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 48, 52, and 64MB of RAM.

    Memory expansion kits are available from Apple. Contact your authorized
    Apple Service Provider for price and installation information.


    Notes
    -----
    * When large amounts of DRAM are installed, the memory check at startup is
    lengthy. There is no software indication that the system is running the
    memory check.

    * The use of 16MB SIMMs has not been thoroughly tested with these Macintosh
    computers and, therefore, available memory configurations when using
    16MB SIMMs are not included in this article.

    * The use of 256K and 2MB SIMMs is not supported for these Macintosh
    models.



Document Information
Product Area: Computers
Category: Macintosh Quadra & Centris
Sub Category: General Topics

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