248 lines
5.2 KiB
ArmAsm
248 lines
5.2 KiB
ArmAsm
; popwr -- code provided by qkumba
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frombuff=$d00 ; sector data to write
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; note these must be contiguous
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encbuf=$e00 ; nibble buffer must be page alined
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bit2tbl=$f00
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readnib = $1001
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readd5aa:
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try_again:
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jsr readnib
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try_for_d5:
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cmp #$d5
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bne try_again
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jsr readnib
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cmp #$aa
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bne try_for_d5
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jsr readnib
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rts
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;================================
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; set up the self-modifying code
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; to point to the proper slot
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;================================
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; slot number is in high nibble of A
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popwr_init:
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and #$70 ; the slot number is in the top here
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sta slotpatchw1+1 ; self modify the code
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sta slotpatchw2+1
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sta slotpatchw3+1
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sta slotpatchw4+1
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rts
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;================================
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; write a sector
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;================================
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sector_write:
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; convert the input to nibbles
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ldy #2 ; why start at 2?
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aa:
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ldx #$aa
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b1:
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dey
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frombuff_smc:
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lda frombuff, y
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lsr
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rol bit2tbl-$aa, x
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lsr
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rol bit2tbl-$aa, x
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sta encbuf, y
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lda bit2tbl-$aa, x
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and #$3f
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sta bit2tbl-$aa, x
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inx
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bne b1
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tya
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bne aa
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jmp cmpsecwr
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.align $100
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; look for the proper sector to write
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cmpsecwr:
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b2:
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jsr readd5aa ; look for dd55aa marker
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cmp #$96
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bne b2
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ldy #3 ; try getting the sector number
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b3:
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jsr readnib
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rol
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sta tmpsec
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jsr readnib
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and tmpsec ; and with prev nibble?
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dey
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bne b3
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requested_sector:
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cmp #$d1
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bne cmpsecwr ; retry if not what we want?
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;skip tail #$DE #$AA #$EB some #$FFs ...
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ldy #$24
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b4:
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dey
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bpl b4
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; c0e0 slot 6 ph0 off
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; c0e1 slot 6 ph0 on
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; c0e2 slot 6 ph1 off
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; c0e3 slot 6 ph1 on
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; c0e4 slot 6 ph2 off
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; c0e5 slot 6 ph2 on
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; c0e6 slot 6 ph3 off
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; c0e7 slot 6 ph3 on
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; c0e8 slot 6 motor off
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; c0e9 slot 6 motor on
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; c0ea slot 6 drive 1
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; c0eb slot 6 drive 2
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; c0ec slot 6 q6 off \ Q6 Q7
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; c0ed slot 6 q6 on |-- state machine 0 0 READ
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; c0ee slot 6 q7 off | 0 1 WRITE
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; c0ef slot 6 q7 on / 1 0 SENSE WRITE PROTECT
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; 1 1 WRITE LOAD
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; write sector data
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slotpatchw1:
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ldx #$d1 ; cycle num smc Q6 Q7
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lda $c08d, x ; prime drive 1 X
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lda $c08e, x ; required by Unidisk 1 0 ; senese wp?
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tya
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sta $c08f, x ; 1 1 ; write load
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ora $c08c, x ; 0 1 ; write
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; 40 cycles
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ldy #4 ; 2 cycles
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cmp $ea ; nop ; 3 cycles
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cmp ($ea,x) ; nop ; 6 cycles
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b5:
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jsr writenib1 ; (29 cycles)
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; +6 cycles
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dey ; 2 cycles
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bne b5 ; 3/2nt
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; 36 cycles
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; +10 cycles
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ldy #(prolog_e-prolog)
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; 2 cycles
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cmp $ea ; nop ; 3 cycles
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b6:
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lda prolog-1, y ; 4 cycles
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jsr writenib3 ; (17 cycles)
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; 32 cycles if branch taken
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; +6 cycles
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dey ; 2 cycles
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bne b6 ; 3/2nt
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; 36 cycles on first pass
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; +10 cycles
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tya ; 2 cycles
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ldy #$56 ; 2 cycles
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b7:
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eor bit2tbl-1, y ; 5 cycles
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tax ; 2 cycles
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lda xlattbl, x ; 4 cycles
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slotpatchw2:
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ldx #$d1 ; slot number smc ; 2 cycles
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sta $c08d, x ; wp sense ; 5 cycles
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lda $c08c, x ; read ; 4 cycles
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; 32 cycles if branch taken
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lda bit2tbl-1, y ; 5 cycles
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dey ; 2 cycles
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bne b7 ; 3/2nt
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; 32 cycles
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; +9 cycles
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clc ; 2 cycles
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b88:
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eor encbuf, y ; 4 cycles
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b8:
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tax ; 2 cycles
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lda xlattbl, x ; 4 cycles
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slotpatchw3:
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ldx #$d1 ; slot number smc ; 2 cycles
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sta $c08d, x ; wp sense ; 5 cycles
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lda $c08c, x ; read ; 4 cycles
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bcs f1 ; 3/2nt
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; 32 cycles if branch taken
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lda encbuf, y ; 4 cycles
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iny ; 2 cycles
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bne b88 ; 3/2nt
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; 32 cycles
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; +10 cycles
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sec ; 2 cycles
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bcs b8 ; 3 cycles
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; 32 cycles
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; +3 cycles
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f1:
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ldy #(epilog_e-epilog)
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; 2 cycles
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cmp ($ea,x) ; nop ; 6 cycles
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b9:
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lda epilog-1, y ; 4 cycles
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jsr writenib3 ; (17 cycles)
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; 32 cycles if branch taken
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; +6 cycles
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dey ; 2 cycles
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bne b9 ;3/2nt
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lda $c08e, x ; read/wp
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lda $c08c, x ; read
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lda $c088, x ; motor off
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rts ; 6 cycles
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writenib1:
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cmp ($ea,x) ; nop ; 6 cycles
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cmp ($ea,x) ; nop ; 6 cycles
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writenib3:
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slotpatchw4:
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ldx #$d1 ; slot number ; 2 cycles
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writenib4:
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sta $c08d, x ; wp sense? ; 5 cycles
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ora $c08c, x ; read ; 4 cycles
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rts ; 6 cycles
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prolog: .byte $ad, $aa, $d5
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prolog_e:
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epilog: .byte $ff, $eb, $aa, $de
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epilog_e:
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xlattbl:
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.byte $96,$97,$9A,$9B,$9D,$9E,$9F,$A6
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.byte $A7,$AB,$AC,$AD,$AE,$AF,$B2,$B3
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.byte $B4,$B5,$B6,$B7,$B9,$BA,$BB,$BC
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.byte $BD,$BE,$BF,$CB,$CD,$CE,$CF,$D3
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.byte $D6,$D7,$D9,$DA,$DB,$DC,$DD,$DE
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.byte $DF,$E5,$E6,$E7,$E9,$EA,$EB,$EC
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.byte $ED,$EE,$EF,$F2,$F3,$F4,$F5,$F6
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.byte $F7,$F9,$FA,$FB,$FC,$FD,$FE,$FF
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