This is an upgrade for your ROM0 IIgs. When you install this upgrade your IIgs will become a ROM1. There are several advantages to upgrading your old ROM0 to a ROM1.
ROM0 vs. ROM1 Differences (credit: Paul W. Good): The main difference is that the ROM 01 has newer versions of the low-level toolsets (version 2.0 of toolsets 1 through 13, instead of version 1.0), which incorporating a lot of bug fixes. The majority of these are also fixed on a ROM 00 machine by running new enough system software (System 2.0 or later), because the system software loads the patches into RAM at startup time.
If you are running old system software, the main benefit of the ROM 01 upgrade is that it will free up some RAM that would otherwise be occupied by these patches, and the same bugs are fixed if you run System 1.0 or 1.1 on a ROM 01.
There is a technical note (TN.IIGS.026) which summarizes the changes in ROM 01 (which it confusingly calls "ROM 2.0"). Apart from toolbox changes, the other significant changes include:
- Detection of disk changes in the Apple 3.5 Drive works correctly.
- AppleTalk bug fixes.
- Applesoft handles horizontal tabbing correctly in 80-column mode.
- Maximum RAM disk size increased to almost 8 MB (instead of 4 MB).
- Interrupt handler bug fixes.
- New monitor command (#) to enable some debugging desk accessories.
- New monitor command (Ctrl-N) to set native mode.
- Serial firmware bug fixes and improvements.
- SmartPort (slot 5) firmware has some bug fixes and better performance.
The most significant difference between ROM 00 and 01 is the fact that System 4.0 and later (all system software based on GS/OS) will not run on ROM 00 - it requires ROM 01 (or ROM 3, which has a different motherboard).
You may run into some old software which only works on ROM 00, because the software broke the rules about how to use the firmware, or relied on old bugs which were fixed.
Any differences in the motherboards you ask? No difference at all. All that changed was the ROM chip itself.
There is one point worth mentioning here: early IIgs machines also had a faulty Video Graphics Controller (VGC) chip, which could also be upgraded for free at the same time as the ROM 01 upgrade.
The symptom of the VGC fault was that monochrome double hi-res graphics mode produced pink fringing effects (it should have been pure black and white) and/or flickering pixels. Some machines exhibited the same symptoms in 80-column text mode, with variable effects depending on the foreground and background colors.
The ROM file is also available >HERE< for free if you wish to burn your own.
If you have any additional tips or info for this product that should be added to this listing please email >Support<. We of ReactiveMicro.com and the Apple II Community thank you!