IIgs ROM1 Adapter

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Revision as of 22:45, 12 September 2018 by RMHenry (talk | contribs)
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Apple IIgs ROM1 Adapter
Current version from ReActiveMicro

The IIgs ROM1 Adapter converts a ROM0 IIgs to a ROM1 by replacing the ROM on the motherboard. It allows an older Apple IIgs system to run newer software like GS/OS. It's user installable, and removable in case the IIgs needs to be downgraded. And unlike other solutions, this one does not block Slot 3 when using a ZIP-GSX or TransWarp GS.

The Adapter project was conceived of and created by Henry from [ReActiveMicro].

Project Status: Complete. In production. Actively sold by ReActiveMicro.

Support: Post on the Discussion page (link above) or email ReActiveMicro Support.

Sales: Visit the ReActiveMicro Store.


Back in 2005 when Henry from ReActiveMicro first returned to the Apple II he found several IIgs systems obtained were ROM0 and couldn't run GS/OS v6.0.1. He also found that some ROM0 IIgs users wanted to upgrade their systems to ROM1. However there isn’t a simple way to do so since Apple used a nonstandard ROM. Henry then found a way to use two Machine Pin Sockets to allow a 27C1001 EPROM to work in place of Apple’s 531000 OTP ROM IC.

Two projects came from this research. One adapter allows for use of a more standard ROM to replace the ROM on the IIgs motherboard. The other adapter allowed for reading the less common 531000 ROM. These adapters however were made from machined pin sockets which also lead to "socket stretch" of the IIgs motherboard socket when used.