The following procedure can be used to check the ROM version:
Synthesizer section only - Serial #s through ZE80899
1) Press PATCH (in the MODE section).
2) Press INFO.
3) While holding NUMBER 6, press CURSOR DOWN (V).
Synthesizer section only - Serial #s ZF00900 and above
1) Power on while holding WRITE, NUMBER 1 and NUMBER 8.
2) Press the BANK 8 button.
Sequencer section only
1) Power on while holding CANCEL and the '0' button.
Synthesizer section only - Serial #s through ZE80899
1) Press PATCH (in the MODE section).
2) Press INFO.
3) While holding NUMBER 6, press CURSOR DOWN (V).
Synthesizer section only - Serial #s ZF00900 and above
1) Power on while holding WRITE, NUMBER 1 and NUMBER 8.
2) Press the BANK 8 button.
Sequencer section only
1) Power on while holding CANCEL and the '0' button.