;; Test keypad input
;; 2023-08-16

; The latest keypress is shown in the top left corner of the display.
; A loop counter is shown in the top right corner; the program ends when it reaches zero.
; (For a 4x4 display.)

#LOOPCOUNT $80

#Z 2          ; the zero flag is #2
#keypad   $20 ; magic memory location containing latest key pressed
#loopIter $FF ; address of loop iterator
#iterPx   $03 ; where to display iterator
#keyPx    $00 ; where to display key

LDA #LOOPCOUNT
STO #loopIter

@loop
 LDA (#loopIter)
 STO #iterPx     ; display loop iterator
 LDA (#keypad)
 STO #keyPx      ; display latest keypress
 LDA (#loopIter)
 SUB 1
 STO #loopIter
 FTG #Z
 FHP #Z
  END
 JMP @loop