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Commodore 1571 firmware
Format Routine

        .page
	.subttl 'lccfmt1.src'      
;
fmtvar   =  $620        ;  put format vars in jump buffer
cnt      =  fmtvar       
num      =  fmtvar+1     
trys     =  fmtvar+3     
tral     =  fmtvar+4     
dtrck    =  fmtvar+6        
remdr    =  fmtvar+7        
sect     =  fmtvar+8     
;
;
;
;*  format routine for lcc
;*
;*
;*
;
;
;
code             
formt   lda  ftnum      ;  test if formatting begun
        bpl  l213       ;  yes
;
        ldx  drive      ;  no,start up by bumping
        lda  #$60       ;  status=stepping
        sta  drvst,x     
;
        lda  #1         ;  drive track =1
        sta  drvtrk,x    
        sta  ftnum      ;  start on track 1
;
        lda  #256-92    ;  bump back 45 steps
        sta  steps       
;
        lda  dskcnt     ; set phase a
        and  #$ff-$03    
        sta  dskcnt      
;
;
        lda  #10        ;  10 errors allowed
        sta  cnt         
;
        lda  #<4000     ;  first guess at track size
        sta  num         
        lda  #>4000      
        sta  num+1       
;
        jmp  end        ;  back to controller
;
;
;
l213    ldy  #0         ;  test if on right track number
        cmp  (hdrpnt),y          
        beq  l214        
;
        sta  (hdrpnt),y ;  goto right track
        jmp  end         
;
;
l214    lda  dskcnt     ;  test for write protect
        and  #$10        
        bne  topp       ;  its ok
;
        lda  #8         ;  write protect error
        jmp  fmterr      
;
topp    jsr  synclr     ;  erase track with sync
;
        jsr  wrtnum     ;  write out num syncs
;
        lda  #$55       ;  write out num non sync
        sta  data2       
;
        jsr  wrtnum      
;
        jsr  kill       ;  kill write
;
        jsr  sync       ;  find sync
;
        lda  #$40       ;  set timer mode
        ora  acr1        
        sta  acr1        
;
        lda  #100-2     ;  set up 100us timer
        sta  t1ll1      ;  cont mode timer
        lda  #0          
        sta  t1hl1      ;  hi latch
        sta  t1hc1      ;  get attention of '22
;
;
;
        ldy  #0         ;  time the sync and nonsync segments
        ldx  #0          
;
fwait   bit  dskcnt     ;  wait for sync
        bmi  fwait       
;
fwait2  bit  dskcnt     ;  wait for no sync
        bpl  fwait2      
;
f000    lda  t1lc1      ;  reset ifr
;
f001    bit  dskcnt     ;  time nonsync area
        bpl  f005       ;  time until sync found
;
        lda  ifr1       ;  test for time out
        asl  a   
        bpl  f001       ;  not yet
;
        inx     	;  .x is lsb
        bne  f000        
        iny     	;  .y is msb
        bne  f000        
;
        lda  #tolong    ;  cant find sync
        jmp  fmterr      
;
f005    stx  t2         ;  save time
        sty  t2+1        
;
        ldx  #0         ;  time sync area
        ldy  #0          
;
f006    lda  t1lc1      ;  reset ifr
;
f007    bit  dskcnt     ;  test for  no sync
        bmi  f009        
;
        lda  ifr1       ;  test for time out
        asl  a   
        bpl  f007        
;
        inx     	;  count up another 100us
        bne  f006        
        iny     	;  msb
        bne  f006        
;
        lda  #tolong    ;  cant be this long
        jmp  fmterr      
;
;
;* now calc the difference between
;* sync and nonsync and adjust
;* num accordingly
;
f009    sec     	;  t1-t2
        txa      
        sbc  t2          
        tax      
        sta  t1          
;
        tya      
        sbc  t2+1        
        tay      
        sta  t1+1        
;
        bpl  f013       ;  get abs(t1-t2)
;
        eor  #$ff       ;  make +
        tay      
        txa      
        eor  #$ff        
        tax      
        inx      
        bne  f013        
        iny      
;
f013    tya     	;  test if abs(t1-t2)<4, that is close enough
        bne  f014       ;  msb must be 0
;
        cpx  #4         ;  test lsb < 4
        bcc  count      ;  its there
;
f014    asl  t1         ;  num=num+(di2)
        rol  t1+1        
;
        clc      
        lda  t1          
        adc  num         
        sta  num         
;
        lda  t1+1        
        adc  num+1       
        sta  num+1       
;
        jmp  topp       ;  try again sam
;
;
count   ldx  #0         ;  now count #bytes in data segment
        ldy  #0          
        clv      
;
cnt10   lda  dskcnt     ;  test for sync
        bpl  cnt20      ;  found sync
        bvc  cnt10      ;  test if byte time
;
        clv     	;  yes, count it
        inx      
        bne  cnt10      ;  keep counting
        iny      
        bne  cnt10      ;  to many ?
;
        lda  #tomany    ;  tomany counts
        jmp  fmterr      
;
cnt20   txa     	;  #bytes=count*2
        asl  a   
        sta  tral+1      
;
        tya      
        rol  a   
        sta  tral        
;
        lda  #$ff-$40   ;  clear cont mode
        and  acr1        
        sta  acr1        
;
;
;.end


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This page has been created by Sami Rautiainen.
Read the small print. Last updated August 27, 1998.