CODE PICK
    HL POPqq,
    chkPS,
    ( x2 )
    L SLAr, H RLr,
    SP ADDHLss,
    C (HL) LDrr,
    HL INCss,
    B (HL) LDrr,
    ( check PS range before returning )
    EXDEHL,
    RAMSTART LDHL(nn), ( RAM+00 == INITIAL_SP )
    DE SUBHLss,
    CC L2 @ JPccnn,    ( abortUnderflow-B298 )
    BC PUSHqq,
;CODE