MVS specific chip that does a bunch of unrelated things.
- S ROM address latch for SFIX, same as S ROM portion of NEO-273
- SM1 /CS output when Z80 is reading from ROM and SM1/SFIX is enabled (SM1CS = SDROM OR SYSTEM)
- /ROMOE output for PROG board (ROMOE = ROMOEU AND ROMEOU)
- Video sync output for JAMMA edge
- Coin counter and coin lockout output