( BOOT DICT: There are only 3 words in the boot dict, but
  these words' offset need to be stable, so they're part of
  the "stable ABI" )
H@ 4 + XCURRENT ! ( make next CODE have 0 prev field )
CODE EXIT ( 0x42 )
    0x14 BCALL,      ( popRS )
    HL PUSH, IY POP, ( --> IP )
    JPNEXT,
CODE (br)            ( 0x53 )
L2 BSET ( used in CBR )
    E 0 IY+ LDrIXY, D 1 IY+ LDrIXY,
    DE ADDIYd,
    JPNEXT,