MC6821 PIA test programs for Lambda-2022 computer

blinkall.s

***
* PIA - Blink All ports
*
* RyuStudio Nov. 2022
***
*
* Lambda-2022 PIA Adrs
p0da      equ $f008       ; PIA0 DA
p0ca      equ p0da+1      ; PIA0 CA
p0db      equ p0da+2      ; PIA0 DB
p0cb      equ p0da+3      ; PIA0 CB
p1da      equ $f010       ; PIA1 DA
p1ca      equ p1da+1      ; PIA1 CA
p1db      equ p1da+2      ; PIA1 DB
p1cb      equ p1da+3      ; PIA1 CB
*
          org $8000
*
initpia   jsr initpia0    ; set all ports on PA and PB to outputs
          ldaa #20
          ldab #$ff
loop      stab p0da
          stab p0db
          jsr wait500ms
          clr p0da
          clr p0db
          jsr wait500ms
          deca
          bne loop
          swi             ; return to MikBug
*
*
*
initpia0  ldx #p0da
          jsr initport
          ldx #p0db
initport  clra
          ldab #$ff
          staa 1,X        ; reset Cx, select DDRx
          stab 0,X        ; set DDRx ; all output
          ldaa #4         
          staa 1,X        ; select PRx
          rts
initpia1  ldx #p1da
          jsr initport
          ldx #p1db
          bra initport
*
wait500ms psha
          ldaa #250
w5loop    jsr wait2ms
          deca
          bne w5loop      ; 2ms * 250 = 500ms
          pula
          rts
*
wait2ms   psha
          clra
w2loop    nop
          deca
          bne w2loop      ; 8us * 256 = 2ms
          pula
          rts
*
          end