lblchkPS BSET ( CX -> expected size )
    AX PS_ADDR MOVxI, AX SP SUBxx, 2 SUBAXI, ( CALL adjust )
    AX CX CMPxx,
    IFNC, ( we're good ) RETn, THEN,
    ( underflow ) DI 0x06 MOVxm, JMPs, lblexec @ RPCs,

PC 3 - ORG @ 1+ ! ( main )
    DX POPx, ( boot drive no ) 0x03 DL MOVmr,
    SP PS_ADDR MOVxI, BP RS_ADDR MOVxI,
    DI 0x08 MOVxm, ( LATEST )
( HERE begins at CURRENT )
    SYSVARS 0x4 ( HERE ) + DI MOVmx,
    SYSVARS 0x2 ( CURRENT ) + DI MOVmx,
    DI 0x04 ( BOOT ) MOVxm,
    JMPn, lblexec @ RPCn, ( execute )