Thankfully, the SE/30 was not significantly bottlenecked in any other manner. This can be corrected either through software, or by replacing the ROM SIMM itself with a 32-bit 'clean' version. The 24-bit ROM means acted as a bottleneck in the system, limiting the amount of memory which can be addressed to 8MB. The Macintosh SE/30 shipped with a 24-bit ROM, often referred to as a 'dirty' ROM.
SIMM socket pinout diagram Signal assigments for the ROM SIMM socket Pin number Generally speaking, the SE/30's architecture has more in common with the Macintosh II family than it does with its predecessor, the SE. The SE/30 ROM is interchangeable with ROMs from the Macintosh IIx, IIfx, and IIcx models. System Software 6.0.3 (and later) patches to the ROM affect the Start Manager, the OS utilities, and the Sony driver. The slot makes it easy to upgrade the ROM. It is installed as a 64-bit ROM SIMM in a socket on the logic board. It is composed of four 512 Kbit ROMs, for a total of 256K, and it is mounted on one ROM SIMM (ROM SIMMs are expandable to 2 MB). The Macintosh SE/30 ROM is identical to that of the Macintosh IIx it includes Color QuickDraw, the Slot Manager, and other features of the IIx ROM. This compares with an access rate of 3.92 MB/sec on the SE, 20 MB/sec on the IIci and 64 MB/sec on the IIfx.
The ROM access rate for the Macintosh SE/30 is 15.67 MB/sec, the same as the Macintosh IIx and IIcx. Because ROM access cycles are not interleaved with video or sound, the processor in a Macintosh computer can always access ROM at the same rate. ROM contains the routines for the Macintosh Toolbox and Operating System, plus the various system traps. Its base address is available as the constant romStart and is also stored in the global variable ROMBase. ROM is the Macintosh computer's permanent read-onl memory. Startup Chime, Happy Mac/Sad Mac icons, Macintosh Toolbox, Color QuickDraw, Slot Manager, other OS routines Signal assigments for the ROM SIMM socket.Macintosh SE/30 ROM < Back to home Table of Contents
SE/30 Forever - Macintosh SE/30 ROM Technical Information
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