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Commodore 1571 firmware
Controller Intialization

        .subttl 'lccinit.src'
	.page   

;     initialization of controller

cntint  lda  #%01101111         ;  data direction
        sta  ddrb2       
        and  #$ff-$08-$04-$03   ;  turn motor off,set phase a, led off
        sta  dskcnt      

;<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>

	jmp  ptch48	; *** rom ds 85 ***
;       lda  pcr2       ;  set edge and latch mode

;<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>

rtch48  and  #$ff-$01   ;  neg edge please

;  ca2: soe output hi disable s.o. into 6502

        ora  #$0e       ; cb1 input only
        ora  #$e0       ; cb2 mode controlw
        sta  pcr2        

        lda  #$41       ;  cont irq, latch mode
        sta  acr2        

;-------25 rom05-bc-------------
        lda  #0          
        sta  t1ll2       
        lda  #tim        8 mirq
        sta  t1hl2       
        sta  t1hc2      ;  get 6522's attention
;----------------------------------

        lda  #$7f       ;  clear all irq sources
        sta  ier2        

        lda  #$80+$40    
        sta  ifr2       ;  clear bit
        sta  ier2       ;  enable irq

        lda  #$ff       ;  no current drive
        sta  cdrive      
        sta  ftnum      ;  init format flag

        lda  #$08       ;  header block id
        sta  hbid        

        lda  #$07       ;  data block id
        sta  dbid        

        lda  #<inact     
        sta  nxtst       
        lda  #>inact     
        sta  nxtst+1     

        lda  #200        
        sta  minstp      

        lda  #4          
        sta  as          

        lda  #$4         
        sta  af


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This page has been created by Sami Rautiainen.
Read the small print. Last updated March 24, 1998.