CODE _TRB! HL POP, chkPS, ( B0 -> B6, B1 -> B2 )
    L RR, RLA, RLA, RLA, RLA, L RR, RLA, RLA, RLA,
    0x44 ANDi, L A LDrr, CPORT_CTL INAi,
    0xbb ANDi, L ORr, CPORT_CTL OUTiA,
;CODE
CODE _THB! HL POP, chkPS, ( B0 -> B7, B1 -> B3 )
    L RR, RLA, RLA, RLA, RLA, L RR, RLA, RLA, RLA, RLA,
    0x88 ANDi, L A LDrr, CPORT_CTL INAi,
    0x77 ANDi, L ORr, CPORT_CTL OUTiA,
;CODE
CODE _D1@ CPORT_D1 INAi, PUSHA, ;CODE
CODE _D2@ CPORT_D2 INAi, PUSHA, ;CODE