Creates a time delay on the 6502. Easy to adapt the intervals or even parameterise the subroutine

6502-time-delay.asm

; Written for the CA65 assembler and tested on a NES emulator
.zeropage
  counter_lsb: .res 1
  counter_msb: .res 1

.proc RateLimit
  lda #$EE        ; Most Significant Byte 'interval'
  sta counter_msb
LOOP_MSB:
  lda #$00        ; Least Significant Byte 'interval'
  sta counter_lsb
LOOP_LSB:
  inc counter_lsb
  lda counter_lsb
  bne LOOP_LSB
  inc counter_msb
  lda counter_msb
  bne LOOP_MSB
  rts
.endproc