Use the first three digits of the serial number on the bottom of the Apple
IIGS to determine which of the two upgrades a computer needs:
- when the first three digits of the computer's serial number are 704
or lower, both the new VGC and the ROM upgrade are required.
- when the first three digits of the computer's serial number are 705
through 724 (inclusive), only the new ROM is required.
- when the first three digits of the computer's serial number are 725 or
higher, neither of the upgrades is required.