This adaptor replaces the original Apple IIGS ROM 0 ROM with a possible 27C1001/27C010/27C020 or equivalent EPROM/EEPROM.
If the EPROM/EEPROM is twice the size of the original ROM such as 27C020, the onboard jumper may be used to select either of the two pages. A preprogrammed 27C1001 128kB (342-0077-B) for ROM01 is included. Write-on space is available on the PCB to document the contents loaded.
This adaptor may also be used on the Apple Macintosh range of computers with suitable boot ROMs. Two adaptors are required for high and low ROMs.
Please note that the adaptor has modern round pins which is not flat. This might stretch the stamped pin socket contacts on the motherboard after multiple insertions. A little light oil or contact cleaner should be added to each pin socket to assist with insertion. Alternatively, a separate stamped pin socket may be inserted first, with the adaptor inserted into that socket to preserve the integrity of the original motherboard socket.