.program z80_write_monitor
.wrap_target
    wait 0 gpio 10        ; /IOREQ asserted
    mov isr, null
    ; IN base is GP0. Capture /OE, DIR, D0-D7, /IOREQ, /RD, CS,
    ; A0 and A1 in their corresponding GPIO bit positions.
    in pins, 15
    push block
    wait 1 gpio 10        ; do not count this bus cycle again
.wrap