NEO-HYCS
Original bodge board from SNK to fix V ROM selection on a few PROGBK2R and PROGBK3R based carts:
Apparently used to disable the V1 ROM for a short period at power on, possibly to allow NEO-PCM2 to read the decryption parameters properly. Removing the board causes corrupt sound or games to show a "bank error".
MM311: Mitsumi PST600D reset generator (4.2V threshold). Forces V1 /CS high at startup, then lets the PCM2 signal through.