Start:
  NOP
  INC R0
  LD R1, R0
  LD [2], R1
  OUT [0], R1
  PUSH -1
  POP [10]
  LD R0, 65
  SYS 0          ; Output character
  LD R0, 1000
  SYS 2          ; Delay 1 second
  JP Start
  LD [R4], [R3]
  HALT