define chrout routine
  inputs a
  trashes a
  @ 65490

define main routine
  trashes a, x, y, z, n, c, v
{
    ld a, 0
    if z {
        ld a, 89
        call chrout
        ld a, 1
    }

    ld a, 65
    call chrout

    ld a, 1
    if z {
        ld a, 89
        call chrout
        ld a, 1
    }
}