Apple IIgs #26
ROM Revision Summary

Revised by Matt Deatherage (September 1989)
Written by Rilla Reynolds (October 1987)

This Technical Note summarizes revisions to the Apple IIGS ROM.

Changes since November 1988: Revised to cover ROM 3.

Apple currently supports two configurations of the Apple IIGS ROM, ROM 1 and ROM 3. In August 1989, Apple IIGS computers began shipping with a 256K ROM, referred to as version 3 or ROM 3 (ROM 2 was skipped since there was already enough confusion about the first version, ROM 0, and the second version, ROM 1). System Software continues to support ROM 1, but it no longer supports ROM 0. Authorized Apple dealers can upgrade older systems (i.e., machines with serial numbers lower than E704...) to ROM 1 upon request.

ROM 1 requires System Software 2.0 or later, while ROM 3 requires System Software 5.0 or later. Although applications may work using older system software releases, they may not function properly due to the coordination of system software and ROM revisions.

Changes from ROM 0 to ROM 1


AppleDisk 3.5


Desk Manager

Event Manager

Integer Math

New Changes:

RAM patches moved to ROM:

Memory Manager

Miscellaneous Tools

RAM patches and enhancements moved to ROM:


QuickDraw II

RAM patches and enhancements moved to ROM:

New QuickDraw changes:



Serial I/O



Text Tools

RAM patches moved to ROM:

Tool Locator

Changes from ROM 1 to ROM 3

ROM 3 is 256K (double the size of ROM 1) and contains several tools which do not exist in ROM 1. The patch file TS3 fixes known bugs in ROM 3 which were discovered after it was frozen. ROM 3 tools are basically System Software 5.0 tools, and the System Software 5.0 documentation covers these tools in detail. This Note only documents non-tool changes.

AppleDisk 3.5 and SmartPort


Control Panel CDA


Serial I/O


The following tools are now in ROM:

Further Reference

This and all of the other Apple II Technical Notes have been converted to HTML by Aaron Heiss as a public service to the Apple II community, with permission by Apple Computer, Inc. Any and all trademarks, registered and otherwise, are properties of their owners.