mirror of https://github.com/A2osX/A2osX.git
583 lines
12 KiB
Plaintext
583 lines
12 KiB
Plaintext
NEW
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AUTO 3,1
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*--------------------------------------
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dcmd .EQ $42 disk command (=1 for read)
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unit .EQ $43 (16*slot)+(128*(drive-1))
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buff .EQ $44 ram address
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blok .EQ $46 disk address
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dent .EQ $48 device call entry address
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idxl .EQ $4a pointer to low page of index block
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idxh .EQ $4c pointer to high page of index block
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idxp .EQ $4e index byte pointer
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iobuff .EQ $60
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* the following are for disk ii only
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dbuf .EQ $26
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BB.Slotn0 .EQ $2b
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oddbits .EQ $3c
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sector .EQ $3d
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BB.RetryCnt .EQ $40
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BB.TargetTrk .EQ $41
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BB.CurrentQTrack .EQ $50
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BB.TargetQTrack .EQ $51
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BB.HdrPtr .EQ $52
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BB.Hdr .EQ $54
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BB.HdrTrk .EQ $55
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BB.HdrVol .EQ $56
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BB.Hdr96 .EQ $57
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BB.tmpTrk .EQ $58
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nbuf1 .EQ $300
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dnib .EQ $2d6
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clrscrn .EQ $fc58
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sosid .EQ $c00
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entlen .EQ sosid+$23
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kernel .EQ $2000
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*--------------------------------------
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.PH $800
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xboot .DA #1
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sec apple iii enters xboot 'ora $38'
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* bcs BB.AppleII branch if not apple iii native mode
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bcc *
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*--------------------------------------
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*BB.AppleIII lda #$9f make apple iii boot using block 1
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* pha the return address is $a000
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* lda #$ff
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* pha
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* inc
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* tax ldx #0
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* inc lda #1 (read block 1)
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* jmp $f479
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*--------------------------------------
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BB.AppleII stx unit save unit number
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cmp #$03 for disk ii
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php save result, it may be irrelevant
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txa find out if disk ii
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and #$70 strip drive # if any
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lsr
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lsr get slot address
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lsr
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lsr
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ora #$c0
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sta dent+1
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ldy #$ff look at last byte
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sty dent
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plp restore carry (if disk ii & sect 0&2 read)
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iny make y=0
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lda (dent),y get device entry addr
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bne ndsk2 branch if not disk ii (16 sector)
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bcs isdsk2 branch if it is disk ii, but block 0 read
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lda #3 make rom read only sector 2
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sta xboot to complete block 0
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inc sector was = 1
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lda dent+1 do rts to re-enter rom
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pha
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lda #$5b
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pha
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rts go read sector 2 into $900
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*--------------------------------------
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isdsk2 sta BB.HdrTrk A=0, make sure previous track =0
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sta dent and dent points at beginning of slot
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ldy #$63 move code from card to ram
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mvboot lda (dent),y
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sta zzstart-$5e,y
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iny
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cpy #$eb have we moved enough?
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bne mvboot
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ldx #mods.cnt now modify code to handle errors.
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modboot ldy mods-1,x
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lda chgs-1,x
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sta zzstart,y
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cpx #8
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bcs .1
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lda endcode-1,x
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sta zzzend-1,x
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.1 dex
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bne modboot
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lda #BB.Hdr
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sta BB.HdrPtr
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stx BB.HdrPtr+1 X=0
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lda /BB.ReadBlock reset device entry
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sta dent+1 to point at disk ii routines.
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lda #BB.ReadBlock get low addr (must be <$80)
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*--------------------------------------
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ndsk2 sta dent save low adr of device call entry.
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stz iobuff
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stz idxl
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stz idxh
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stz idxp
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stz blok+1
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ldy #1
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sty dcmd set read command.
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iny y=2
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sty blok to read directory blocks
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lda #$c 2-5 at $c00
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sta iobuff+1
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sta idxl+1
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rddir jsr goread call read block routine.
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bcs bterr2 give up on error.
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* inc iobuff+1
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* inc iobuff+1
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inc blok
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lda blok have all directory blocks been read?
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cmp #6
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bcc rddir loop if not.
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*--------------------------------------
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lda #4 begin look-up with first entry past header.
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.HS 2C BIT ABS
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nxdent lda idxl
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nxdent1 clc
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adc entlen bump to next directory entry.
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tay save in y for now.
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bcc nxdent2 branch if not a page cross.
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inc idxl+1
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lda idxl+1 check for new block.
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lsr if even then new block.
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bcs nxdent2
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cmp #$a have all file names been compared?
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beq booterr branch if no pro.kernel.
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ldy #4 else, begin at block beginning.
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nxdent2 sty idxl
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ldy #6
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lookpro lda (idxl),y look for matching name.
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cmp BB.FX.ProDOS,y
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bne nxdent branch if no match.
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dey
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bpl lookpro
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* ldy #$10 get file type & index block addr.
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* lda (idxl),y
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* cmp #S.FI.T.SYS is it a system file?
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* bne booterr
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* iny
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ldy #$11
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lda (idxl),y
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sta blok
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iny
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lda (idxl),y
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sta blok+1
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stz idxl
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ldy #$1e read index block at $1e00 and
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sty idxl+1 kernel at $2000
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sty iobuff+1
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iny
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sty idxh+1
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*--------------------------------------
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rdkernl jsr goread read index block.
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bterr2 bcs booterr
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* inc iobuff+1
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* inc iobuff+1
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ldy idxp get index pointer
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inc idxp bump for next time.
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lda (idxl),y
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sta blok
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lda (idxh),y high disk addr.
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sta blok+1
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ora (idxl),y if both=0 then done.
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bne rdkernl branch if more to read.
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jmp kernel go execute kernel code.
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*--------------------------------------
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booterr jsr clrscrn clear video
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ldy #BB.MSG.ERR.Len-1
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.1 lda BB.MSG.ERR,y
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sta $5b6,y
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dey
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bpl .1
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jmp $ff69
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*--------------------------------------
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goread
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* lda iobuff
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stz buff
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lda iobuff+1
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sta buff+1
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inc iobuff+1
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inc iobuff+1
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jmp (dent)
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*--------------------------------------
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mods .DA #mod1,#mod2,#mod3,#mod4,#mod5,#mod6,#mod7,#mod8,#mod8+1,#mod9
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mods.cnt .EQ *-mods
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chgs .DA #chg1,#chg2,#chg3,#chg4,#chg5,#chg6,#chg7,#$91,#BB.HdrPtr,#BB.HdrTrk
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endcode ldx BB.Slotn0
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clc
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rts
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jmp BB.FX.SeekRead
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*--------------------------------------
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BB.MSG.ERR .AS -"BOOT ERROR"
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BB.MSG.ERR.Len .EQ *-BB.MSG.ERR
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BB.FX.ProDOS .DA #$26 $20 = storage type + 6 = "PRODOS" len
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.AS "PRODOS"
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*--------------------------------------
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BB.ReadBlock lda blok figure out track & sector.
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and #7 strip track for now.
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cmp #4
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and #3
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php
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asl
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plp
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rol now we have the first sector of block.
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sta sector
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lda blok+1 get high block #
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lsr shift hi addr to carry.
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lda blok now figure track #
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ror
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lsr
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lsr
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sta BB.TargetTrk
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*--------------------------------------
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lda buff+1
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sta dbuf+1
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ldx BB.Slotn0
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lda IO.D2.DrvOn,x
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jsr BB.FX.SeekRead
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inc dbuf+1 bump address
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inc sector
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inc sector and sector #
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bcs .9 branch if error.
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jsr BB.FX.Read
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.9 ldy IO.D2.DrvOff,x
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rts return error status in carry.
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*--------------------------------------
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BB.Wait100usecA phx (3)
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.1 ldx #20 (2)
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.2 dex (2)
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bne .2 (3)
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dec (2)
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bne .1 (3)
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plx (4)
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rts (6)
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*--------------------------------------
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BB.Trk2Qtrk ldy BB.HdrVol
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beq .5
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cpy #$85
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bcs .5 > 192 ? must be a buggy 254
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sta BB.tmpTrk
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tya
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bpl .1
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lsr BB.HdrVol 2 sides
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.1 and #%00000111 stepping
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tay
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lda #0
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clc
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.2 adc BB.tmpTrk
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dey
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bne .2
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rts
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.5 asl
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asl
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BB.Trk2Qtrk.RTS rts
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*--------------------------------------
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BB.FX.SeekRead lda BB.TargetTrk
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jsr BB.Trk2Qtrk
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sta BB.TargetQTrack
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lda BB.HdrTrk get track we're on
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jsr BB.Trk2Qtrk
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sta BB.CurrentQTrack
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cmp BB.TargetQTrack
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beq BB.FX.Read
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bit #1
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bne .1
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jsr .20 we are on 0/4 or 2/4 track
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bra .10 no wait, next operation will be phy/plx/Ph0On,y
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.1 cmp BB.TargetQTrack we are on 1/4 or 3/4
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bcs .2 if CS, C > T, must move out
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inc CC: C < T, ON next PH
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.HS B0 BCS
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.2 dec CS: C > T, ON prev PH
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sta BB.CurrentQTrack
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bra .6 Ph ON to go to 0/4 or 2/4, then wait
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*--------------------------------------
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.20 and #6
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ora BB.Slotn0
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tay
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lda IO.D2.Ph0On,y
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rts
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*--------------------------------------
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.3 bcs .4 if CS, C > T, must move out
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inc CC: C < T, ON next PH
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.HS B0 BCS
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.4 dec CS: C > T, ON prev PH
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sta BB.CurrentQTrack
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bit #1
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bne .5 we must go to 1/4 or 3/4
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lda IO.D2.Ph0Off,x we must go to 0/4 or 2/4 : Off Prev Ph
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bra .8 go wait....
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.5 phy we must go on 1/4 or 3/4
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plx Y already ON, -> X for Ph0Off,x
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bcs .6 if CS, C > T, must move out
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inc CC: C < T, ON next PH
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.6 jsr .20 now X and Y on
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.8 lda #IO.D2.SeekTimeB
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.9 jsr BB.Wait100usecA ...wait...
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.10 lda BB.CurrentQTrack
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cmp BB.TargetQTrack
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bne .3
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lsr CS if X,Y on
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lda #0
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jsr BB.Wait100usecA
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lda IO.D2.Ph0Off,y
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bcc .11
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lda IO.D2.Ph0Off,x
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.11
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*--------------------------------------
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BB.FX.Read ldx BB.Slotn0
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stz BB.RetryCnt
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php
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tryread plp fix stack.
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rdhead sec anticipate error.
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inc BB.RetryCnt if = 0 then give up!
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beq BB.Trk2Qtrk.RTS branch if can't fine/read sector.
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clc indicate reading header.
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ldy #0 Retry cnt waiting D5
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rddata php carry set if reading sector.
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rd0 iny
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beq tryread
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*--------------------------------------
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* from zzstart to zzend code is moved from rom and modified to match this code...
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*--------------------------------------
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zzstart .EQ *
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rd1 lda IO.D2.RData,x read a byte from the state machine.
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bpl rd1 loop until ready.
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.DUMMY
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rd1a eor #$d5 mark 1?
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mod1 .EQ *-zzstart+1
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bne rd0 branch if not.
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chg1 .EQ rd0-*
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rd2 lda IO.D2.RData,x
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bpl rd2
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cmp #$aa mark 2?
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bne rd1a
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nop waste a little time.
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rd3 lda IO.D2.RData,x
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bpl rd3
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cmp #$96 header mark 3?
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beq rdhd1 branch if it is.
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plp were we looking for data mark 3?
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mod2 .EQ *-zzstart+1
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bcc rdhead branch if not.
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chg2 .EQ rdhead-*
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eor #$ad data mark 3?
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beq rddt1 go read data field if true...
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mod3 .EQ *-zzstart+1
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rdhd0 bne rdhead otherwise, start over.
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chg3 .EQ rdhead-*
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rdhd1 ldy #3 read in trk,sect,&volume #.
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mod8 .EQ *-zzstart
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rdhd2 sta (BB.HdrPtr),y save last result in .. , BB.HdrTrk , BB.HdrVol , ..
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rdhd3 lda IO.D2.RData,x
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bpl rdhd3
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rol
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sta oddbits save odd bits (7,5,3,1)
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rdhd4 lda IO.D2.RData,x
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bpl rdhd4
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and oddbits combine even and odd to form value.
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dey
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bne rdhd2 read in next pair.
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plp
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cmp sector last byte formed is sector#
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mod4 .EQ *-zzstart+1
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bne rdhead branch if target sector not found.
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chg4 .EQ rdhead-*
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mod9 .EQ *-zzstart+1
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lda BB.HdrTrk previous result is track #
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cmp BB.TargetTrk is desired track found?
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mod5 .EQ *-zzstart+1
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bne goseek re-seek if mismatch.
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chg5a .EQ *
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mod6 .EQ *-zzstart+1
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bcs rddata branch if proper track always.
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chg6 .EQ rddata-*
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*--------------------------------------
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rddt1 ldy #$56 read 2 bit groupings first.
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rddt1a sty oddbits
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rddt2 ldy IO.D2.RData,x
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bpl rddt2
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eor dnib,y denibblize using table left from boot rom.
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ldy oddbits save in nbuf1
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dey
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sta nbuf1,y
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bne rddt1a loop until all 86 groups are read.
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rddt3 sty oddbits now count up for 6-bit groups.
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rddt4 ldy IO.D2.RData,x
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bpl rddt4
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eor dnib,y
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ldy oddbits save result to specified buffer.
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sta (dbuf),y
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iny
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bne rddt3 loop for 256 bytes.
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rdchk ldy IO.D2.RData,x now verify checksum...
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bpl rdchk
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eor dnib,y must be equal...
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mod7 .EQ *-zzstart+1
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bne rdhd0 branch if error.
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chg7 .EQ rdhd0-*
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ldy #0 make y=0
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nxttwo ldx #$56 now combine 2-bit group with 6 bit group
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twobit dex all done with this group?
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bmi nxttwo branch if so.
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lda (dbuf),y
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lsr nbuf1,x
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rol
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lsr nbuf1,x
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rol
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sta (dbuf),y
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iny
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bne twobit
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*--------------------------------------
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zzzend ldx BB.Slotn0
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clc indicate good read.
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rts
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chg5 .EQ *-chg5a
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goseek jmp BB.FX.SeekRead
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.ED
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*--------------------------------------
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.LIST ON
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BB.Free .EQ $a00-*
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.BS BB.Free
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.LIST OFF
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.EP
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*--------------------------------------
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MAN
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SAVE usr/src/shared/x.bb.fx.s
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