Apple System Profiler reports the revision as $77D.40F2

The Rev "A" ZIF ROM was installed in the Power Macintosh G3./233 and 266 models, all styles(Desktop, Minitower and the All In One machine).

I have personally seen a total of 5 different Rev "A" ROMs. The first 3 only show differences in the date stamp on the identifying sticker, the others are much easier to see the differences with.

Rev "A" ROM Generation 1-3 front side of chip

Rev "A" ROM Generation 1-3 rear side of chip

This marking is on the front leftmost side of the first 3 generations of the Rev "A" ROMS.

These stickers are on the front of the ROM, on the left chip of the most early Rev "A" ROMs, generation 1-3. The ones that are pictured above are stamped with the week of production showing the 7th, 19th and the 21st week all of 1998.

This marking is on the leftmost side of the rear of the first
3 generations of the Rev "A" ROM chips.

Rev "A" ROM 4th generation chip front

Rev "A" ROM 4th generation chip rear

These are the markings on the 4th. generation Rev "A" ROM front side. Note the placement of the holes differ from the earliest models of Rev "A" ZIF ROM.

This marking is on the leftmost side of the rear of the 4th generation of the Rev "A" ROM chips. Note the placement of the hole in the chip is different than the first 3 generations of ROM chip.

This marking is on the rightmost side of the rear of the Rev "A" 4th generation ROM chip.
Note the designation -01.

Rev "A" ROM 5th generation chip front

Rev "A" ROM 5th generation chip rear

These are the markings on the 5th generation Rev "A" ROMs front side. Note that there is no longer a marking on the leftmost side that says "WRAITH ROM", and the revision of the chip has changed from -01 to -A.

This marking is on the leftmost side of the rear of the 5th generation of the Rev "A" ROM chips. Note the revision of the chip has changed from -01 to -A. The hole placement is the same as the 4th generation of the Rev "A" chip.

This marking is on the rightmost rear of the 5th generation Rev "A" ROM chip.
Note the deisgnation -02