Update - Its protected by a GAL.
It should be possible to create an equivalent GAL by following the clues here:
http://www.amiga.org/forums/showthread.php?t=29356&page=2You should even be able to do it with TTL/PAL/PIC if you feel like it.
If I didn't have so much trouble finding an A2091 without getting ripped off then I might be tempted to have a go.
