Questions on Rom revisions:
1. Is Rom 3 the best and fully compatible with all software or have it's quirks? Is there some reason people would want to stick with Rom 01?
2. What are my options to upgrade a Rom 00?
I learned my Woz Edition GS is a Rom 00 and much software won't run on it. I have a CFFA3000 on the way for floppy and hard disk emulation (but I don't think it functions for Rom help) and want to really dive in to GS exclusive software. I heard one can't upgrade Rom 0 to Rom 3 because it is TWO chips and mine would only have space for one. I do see ebay listings for Eprom versions and would love to know if there is some way to get my GS to Rom 3 or advice on that over Rom 01 options. Thanks!
AFAIK you cannot upgrade a ROM 00 or ROM 01 board to be a ROM 3 as there were physical changes made to the motherboard in addition to having a larger ROM chip.
You *can and should* upgrade to a ROM 01 though. Quite a few bugs were fixed in the ROM01 and additional toolsets added that arguably has the *best* compatibility of all ROM versions. You can run the latest versions of the System Software in addition to pretty much everything else.
The reason that the ROM 01 is considered the most compatible is due to a number (a small number mind you) of older software titles being written for the ROM 01 that didn't follow Apple's programming guidelines and consequently this software was incompatible with the ROM 3 when it was released.
Now having said all of that, most incompatible software has been patched to run on the ROM 3 these days, so I find it to be my "favourite" as it has the additional RAM on board and more Toolsets in ROM. However, you can't go too wrong with either a ROM 01 or ROM 3.
As for upgrading to a ROM 01, your best bet would be to contact ReactiveMicro or wait for one of these to come back in stock:
AppleIIGSxROM
I have both ROM 1 and ROM 3 IIgs. I basically never use the ROM 1 GS except to turn it on every 1 or 2 years to see that it's still working. The ROM 3 is so much better. I have not come across any incompatible software.
(I'm not saying that there are no incompatibilities, just that no software I've ever run has been incompatible.)
Fantastic info, thanks! So if I offset the RAM advantages of a ROM3 with a GGlabs 4MB card, can I get a ROM1 from this ebay link: https://tinyurl.com/y7vlaft2 and be done with it?
The eBay listing doesn't specifically state IIgs ROM upgrades, so probably best to contact the seller (ReactiveMicro) to make sure that is covered by this sale. I don't remember offhand what EPROM is required for the IIgs ROM.
A2Heaven makes a ROM upgrade for the IIgs Rev 00 to 01 and it has some other slight version included.
One of the things about the Rom 3 was it had more RAM from factory.
ROM 3 also has an improved ADB controller that can operate the green LEDs on an Apple Extended Keyboard.
The change from ROM 1 to ROM 3 was more than just a ROM upgrade.
I thank everyone for the bonus info about the benefits of ROM 3, but it sounds like as of 2018, there has not been an option of Rom 00 machines to upgrade to 03, but 01 is possible. I'll focus on my available options for that
Looks like the two linked options are the only ones around and both out of stock.
Hopefully one option will return soon. a2heaven is interesting:
You can switch betwen four ROM-s pre programmed on Adapter .
0 : ROM 00
1 : ROM 01
2: eng Alpha 2.0
3 : ROMBF
Anyone have a link to details of the latter two Roms? I never heard about these.
They are ROMs that have been found and dumped from early development or prototype machines. I don't think a lot is known about the differences.
Even though something is out of stock at A2Heaven, it may not be so - I would suggest you contact Plamen, most of the time he will make you one