;  s21 with interrupt

.symbol
  cnt   100

.code 0
  jmp main

:isr    ; interrupt service routine
  ld r1 cnt
  add r1 r1 #1
  trap r1 #1
  st r1 cnt
  reti

:main
  mov r1 #isr
  st r1 1000     ; set int vec

  mov r1 #0
  st r1 cnt
:while
  trap r0 #17    ; sleep and wait for int
  jmp while
;  int #0         ; test as21

.data 100
.end
