**************************
*                        *
* APPLE-II HI-RESOLUTION *
*  GRAPHICS SUBROUTINES  *
*                        *
*    BY WOZ   9/13/77    *
*                        *
*  ALL RIGHTS RESERVED   *
*                        *
**************************

*  HI-RES EQUATES
SHAPEL EQU   $1A POINTER TO
SHAPEH EQU   $1B     SHAPE LIST
HCOLOR1 EQU   $1C     RUNNING COLOR MASK
COUNTH EQU   $1D
HBASL  EQU   $26 BASE ADR FOR CURRENT
HBASH  EQU   $27  HI-RES PLOT LINE. A
HMASK  EQU   $30
A1L    EQU   $3C MONITOR A1.
A1H    EQU   $3D
A2L    EQU   $3E MONITOR A2.
A2H    EQU   $3F
LOMEML EQU   $4A BASIC 'START OF VARS'.
MOMEMH EQU   $4B
DXL    EQU   $50 DELTA-X FOR HLIN, SHAPE.
DXH    EQU   $51
SHAPEX EQU   $51 SHAPE TEMP.
DY     EQU   $52 DELTA-Y FOR HLIN, SHAPE.
QDRNT  EQU   $53 ROT QUADRANT (SHAPE).
EL     EQU   $54 ERROR FOR HLIN.
EH     EQU   $55
PPL    EQU   $CA BASIC START OF PROG PTR.
PPH    EQU   $CB
PVL    EQU   $CC BASIC END OF VARS PTR.
PVH    EQU   $CD
ACL    EQU   $CE BASIC ACC.
ACH    EQU   $CF
X0L    EQU   $320 PRIOR X-COORD SAVE
X0H    EQU   $321 AFTER HLIN OR HPLOT.
Y0     EQU   $322 HLIN, HPLOT Y-COORD SAVE.
BXSAV  EQU   $323 X-REG SAVE FOR BASIC.
HCOLOR EQU   $324 COLOR FOR HPLOT, HPOSN
HNDX   EQU   $325 HORIZ OFFSET SAVE.
HPAG   EQU   $326 HI-RES PAGE ($20 NORMAL)
SCALE  EQU   $327 SCALE FOR SHAPE, MOVE.
SHAPXL EQU   $328 START OF
SHAPXH EQU   $329   SHAPE TABLE.
COLLSN EQU   $32A COLLISION COUNT.
HIRES  EQU   $C057 SWITCH TO HI-RES VIDEO
MIXSET EQU   $C053 SELECT TEXT/GRAPHICS MIX
TXTCLR EQU   $C050 SELECT GRAPHICS MODE.
MEMFUL EQU   $E36B BASIC MEM FULL ERROR.
RNGERR EQU   $EE68 BASIC RANGE ERROR.
ACADR  EQU   $F11E 2-BYTE TAPE READ SETUP.
RD2BIT EQU   $FCFA TWO-EDGE TAPE SENSE.
READ   EQU   $FEFD TAPE READ (A1.A2).
READX1 EQU   $FF02 READ WITHOUT HEADER.

*  HIGH RESOLUTION GRAPHICS INITS
*
* ROM VERSION $D000 TO $D3FF
*
       ORG   $D000
       OBJ   $A000
SETHRL LDA   #$20 INIT FOR $2000-3FFF
       STA   HPAG HI-RES SCREEN MEMORY.
       LDA   HIRES SET HIRES DISPLAY MODE
       LDA   MIXSET WITH TEXT AT BOTTOM.
       LDA   TXTCLR SET GRAPHICS DISPLAY MODE
HCLR   LDA   #$0
BKGND0 STA   HCOLOR1 SET FOR BLACK BKGND.
BKGND  LDA   HPAG
       STA   SHAPEH INIT HI-RES SCREEN MEM
       LDY   #$0 FOR CURRENT PAGE, NORMALLY
       STY   SHAPEL $2000-3FFF OR $4000-5FFF
BKGND1 LDA   HCOLOR1
       STA   (SHAPEL),Y
       JSR   CSHFT2 (SHAPEL,H) WILL SPECIFY
       INY   32 SEPARATE PAGES.
       BNE   BKGND1 THROUGHOUT THE INIT.
       INC   SHAPEH
       LDA   SHAPEH
       AND   #$1F TEST FOR DONE.
       BNE   BKGND1
       RTS

*  HI-RES GRAPHICS POSITION AND PLOT SUBRS
HPOSN  STA   Y0 ENTER WITH Y IN A-REG,
       STX   X0L XL IN X-REG,
       STY   X0H AND XH IN Y-REG.
       PHA
       AND   #$C0
       STA   HBASL FOR Y-COORD = 00ABCDEF.
       LSR   ;CALCULATES BASE ADDRESS
       LSR   ;IN HBASL, HBASH FOR
       ORA   HBASL    ACCESSING SCREEN MEM
       STA   HBASL    VIA (HBASL),Y ADDRESSING MODE
       PLA
       STA   HBASH
       ASL   ;CALCULATES
       ASL   ;HBASH = PPPFGHCD
       ASL   ;HBASL = EABAB000
       ROL   HBASH
       ASL   ;WHERE PPP=001 FOR $2000-3FFF
       ROL   HBASH SCREEN MEM RANGE AND
       ASL   ; PPP=010 FOR $4000-7FFF
       ROR   HBASL (GIVEN Y-COORD=ABCDEFGH)
       LDA   HBASH
       AND   #$1F
       ORA   HPAG
       STA   HBASH
       TXA   DIVIDE X0 BY 7 FOR
       CPY   #$0 INDEX FROM BASE ADR
       BEQ   HPOSN2 (QUOTIENT) AND BIT
       LDY   #$23 WITHIN SCREEN MEM BYTE
       ADC   #$4 (MASK SPEC'D BY REMAINDER)
HPOSN1 INY
HPOSN2 SBC   #$7 SUBTRACT OUT SEVENS
       BCS   HPOSN1
       STY   HNDX WORKS FOR X0 FROM
       TAX   0 TO 279, LOW-ORDER
       LDA   MSKTBL-249,X BYTE IN X-REG,
       STA   HMASK HIGH IN Y-REG ON ENTRY
       TYA
       LSR   ; IF ON ODD BYTE (CARRY SET)
       LDA   HCOLOR THEN ROTATE HCOLOR ONE
HPOSN3 STA   HCOLOR1 BIT FOR 180 DEGREE SHIFT
       BCS   CSHFT2 PRIOR TO COPYING TO HCOLOR1.
       RTS
HPLOT  JSR   HPOSN
HPLOT1 LDA   HCOLOR1 CALC BIT POSN IN HBASL,H
       EOR   (HBASL),Y HNDX, AND HMASK FROM
       AND   HMASK Y-COORD IN A-REG,
       EOR   (HBASL),Y X-COORD IN X,Y-REGS.
       STA   (HBASL),Y FOR ANY 'L' BITS OF HMASK
       RTS   SUBSTITUTE CORRESPONDING
*                   BIT OF HCOLOR1.

*  HI-RES GRAPHICS L,R,U,D SUBRS
LFTRT  BPL   RIGHT USE SIGN FOR LFT/RT SELECT
LEFT   LDA   HMASK
       LSR   ; SHIFT LOW-ORDER
       BCS   LEFT1 7 BITS OF HMASK
       EOR   #$C0 ONE BIT TO LSB.
LR1    STA   HMASK
       RTS
LEFT1  DEY   DECR HORIZ INDEX.
       BPL   LEFT2
       LDY   #$27 WRAP AROUND SCREEN.
LEFT2  LDA   #$C0 NEW HMASK, RIGHTMOST
NEWNDX STA   HMASK DOT OF BYTE.
       STY   HNDX UPDATE HORIZ INDEX.
CSHIFT LDA   HCOLOR1
CSHFT2 ASL   ; ROTATE LOW-ORDER
       CMP   #$C0 7 BITS OF HCOLOR1
       BPL   RTS1 ONE BIT POSN.
       LDA   HCOLOR1
       EOR   #$7F ZXYXYXYX -> ZYXYXYXY
       STA   HCOLOR1
RTS1   RTS
RIGHT  LDA   HMASK
       ASL   ; SHIFT LOW-ORDER
       EOR   #$80 7 BITS OF HMASK
       BMI   LR1 ONE BIT TO MSB.
       LDA   #$81
       INY   NEXT BYTE.
       CPY   #$28
       BCC   NEWNDX
       LDY   #$0 WRAP AROUND SCREEN IF >279
       BCS   NEWNDX ALWAYS TAKEN.

*  L,R,U,D, SUBROUTINES.
LRUDX1 CLC   NO 90 DEG ROT (X-OR).
LRUDX2 LDA   SHAPEX
       AND   #$4 IF B2=0 THEN NO PLOT.
       BEQ   LRUD4
       LDA   #$7F FOR EX-OR INTO SCREEN MEM
       AND   HMASK
       AND   (HBASL),Y SCREEN BIT SET?
       BNE   LRUD3
       INC   COLLSN
       LDA   #$7F
       AND   HMASK
       BPL   LRUD3 ALWAYS TAKEN.
LRUD1  CLC   NO 90 DEG ROT.
LRUD2  LDA   SHAPEX
       AND   #$4 IF B2=0 THEN NO PLOT.
       BEQ   LRUD4
       LDA   (HBASL),Y
       EOR   HCOLOR1 SET HI-RES SCREEN BIT
       AND   HMASK TO CORRESPONDING HCOLOR1
       BNE   LRUD3 IF BIT OF SCREEN CHANGES
       INC   COLLSN THEN INCR COLLSN DETECT
LRUD3  EOR   (HBASL),Y
       STA   (HBASL),Y
LRUD4  LDA   SHAPEX ADD GDRNT TO
       ADC   QDRNT SPECIFIED VECTOR
       AND   #$3 AND MOVE LFT, RT,
EQ3    EQU   *-1 UP, OR DWN BASED
       CMP   #$2 ON SIGN AND CARRY.
       ROR
LRUD   BCS   LFTRT
UPDWN  BMI   DOWN4 SIGN FOR UP/DWN SELECT
UP     CLC
       LDA   HBASH CALC BASE ADDRESS
       BIT   EQ1C (ADR OF LEFTMOST BYTE)
       BNE   UP4 FOR NEXT LINE UP
       ASL   HBASL IN (HBASL, HBASH)
       BCS   UP2 WITH 192-LINE WRAPAROUND
       BIT   EQ3
       BEQ   UP1
       ADC   #$1F **** BIT MAP ****
       SEC
       BCS   UP3 FOR ROW = ABCDEFGH
UP1    ADC   #$23
       PHA
       LDA   HBASL HBASL = EABAB000
       ADC   #$B0 HBASH = PPPFGHCD
       BCS   UP5
       ADC   #$F0 WHERE PPP=001 FOR PRIMARY
UP5    STA   HBASL HI-RES PAGE ($2000-$3FFF)
       PLA
       BCS   UP3
UP2    ADC   #$1F
UP3    ROR   HBASL
UP4    ADC   #$FC
UPDWN1 STA   HBASH
       RTS
DOWN   CLC
DOWN4  LDA   HBASH
       ADC   #$4 CALC BASE ADR FOR NEXT LINE
EQ4    EQU   *-1 DOWN TO (HBASL,HBASH)
       BIT   EQ1C
       BNE   UPDWN1
       ASL   HBASL WITH 192-LINE WRAPAROUND
       BCC   DOWN1
       ADC   #$E0
       CLC
       BIT   EQ4
       BEQ   DOWN2
       LDA   HBASL
       ADC   #$50
       EOR   #$F0
       BEQ   DOWN3
       EOR   #$F0
DOWN3  STA   HBASL
       LDA   HPAG
       BCC   DOWN2
DOWN1  ADC   #$E0
DOWN2  ROR   HBASL
       BCC   UPDWN1

* HI-RES GRAPHICS LINE DRAW SUBRS
HLINRL PHA
       LDA   #$0 SET (X0L,X0H) AND
       STA   X0L Y0 TO ZERO FOR
       STA   X0H REL LINE DRAW
       STA   Y0 (DX, DY).
       PLA
HLIN   PHA   ON ENTRY
       SEC   XL: A-REG
       SBC   X0L XH: X-REG
       PHA   Y: Y-REG
       TXA
       SBC   X0H
       STA   QDRNT CALC ABS(X-X0)
       BCS   HLIN2 IN (DXL,DXH)
       PLA
       EOR   #$FF X DIR TO SIGN BIT
       ADC   #$1 OF QDRNT.
       PHA   0=RIGHT (DX POS)
       LDA   #$0 1=LEFT (DX NEG)
       SBC   QDRNT
HLIN2  STA   SHAPEX
       STA   EH INIT (EL,EH) TO
       PLA   ABS(X-X0)
       STA   DXL
       STA   EL
       PLA
       STA   X0L
       STX   X0H
       TYA
       CLC
       SBC   Y0 CALC -ABS(Y-0)-1
       BCC   HLIN3 IN DY.
       EOR   #$FF
       ADC   #$FE
HLIN3  STA   DY ROTATE Y DIR INTO
       STY   Y0 QDRNT SIGN BIT
       ROR   QDRNT (0=UP, 1=DOWN)
       SEC
       SBC   DXL INIT (COUNTL, COUNTH).
       TAX   TO -(DELTX+DELTY+1)
       LDA   #$FF
       SBC   DXH
       STA   COUNTH
       LDY   HNDX HORIZ INDEX
       BCS   MOVEX2 ALWAYS TAKEN.
MOVEX  ASL   ; MOVE IN X-DIR. USE
       JSR   LFTRT GDRNT B6 FOR LFT/RT SELECT
       SEC
MOVEX2 LDA   EL ASSUME CARRY SET.
       ADC   DY (EL,EH)-DELTY TO (EL,EH)
       STA   EL NOTE: DY IS (-DELTY)-1
       LDA   EH CARRY CLR IF (EL,EH)
       SBC   #$0 GOES NEG.
HCOUNT STA   EH
       LDA   (HBASL),Y SCREEN BYTE.
       EOR   HCOLOR1 PLOT DOT OF HCOLOR1.
       AND   HMASK CURRENT BIT MASK.
       EOR   (HBASL),Y
       STA   (HBASL),Y
       INX   DONE (DELTX+DELTY)
       BNE   HLIN4 DOTS?
       INC   COUNTH
       BEQ   RTS2 YES, RETURN.
HLIN4  LDA   QDRNT FOR DIRECTION TEST
       BCS   MOVEX IF CAR SET, (EL, EH) POS
       JSR   UPDWN IF CLR, NEG, MOVE YDIR
       CLC
       LDA   EL (EL,EH)+DELTX
       ADC   DXL TO (EL,EH).
       STA   EL
       LDA   EH CAR SET IF (EL,EH) GOES POS
       ADC   DXH
       BVC   HCOUNT ALWAYS TAKEN
MSKTBL HEX   81 LEFTMOST BIT OF BYTE.
       HEX   82,84,88
       HEX   90,A0
       HEX   C0 RIGHTMOST BIT OF BYTE.
EQ1C   HEX   1C
COS    HEX   FF,FE,FA,F4,EC,E1,D4,C5,B4
       HEX   A1,8D,78,61,49,31,18,FF

*  HI-RES GRAPHICS COORDINATE RESTORE SUBR
HFIND  LDA   HBASL
       ASL   ; CONVERTS BASE ADR
       LDA   HBASH TO Y-COORD
       AND   #$3
       ROL   ; FOR HBASL = EABAB000
       ORA   HBASL HBASH = PPPFGHCD
       ASL
       ASL   ; GENERATE
       ASL   ; Y-COORD = ABCDEFGH
       STA   Y0
       LDA   HBASH (PPP=SCREEN PAGE,
       LSR   ; NORMALLY 001 FOR
       LSR   ; $2000-$3FFF
       AND   #$7 HI-RES SCREEN)
       ORA   Y0
       STA   Y0 CONVERTS HNDX (INDEX
       LDA   HNDX FROM BASE ADR)
       ASL   ; AND HMASK (BIT
       ADC   HNDX MASK) TO X-COORD
       ASL   ; IN (X0L, X0H)
       TAX   (RANGE $0-$133)
       DEX
       LDA   HMASK
       AND   #$7F
HFIND1 INX
       LSR
       BNE   HFIND1
       STA   X0H
       TXA
       CLC   CALC HNDX*7+
       ADC   HNDX LOG (BASE 2) HMASK.
       BCC   HFIND2
       INC   X0H
HFIND2 STA   X0L
RTS2   RTS

*  HI-RES GRAPHICS SHAPE DRAW SUBR
*
* SHAPE DRAW
* R = 0 TO 63
* SCALE FACTOR USED (1=NORMAL)
*
DRAW   STX   SHAPEL DRAW DEFINITION
       STY   SHAPEH POINTER
DRAW1  TAX
       LSR   ; ROT ($0=$3F)
       LSR
       LSR   ; GRDNT 0=UP, 1=RT,
       LSR   ; 2=DWN, 3=LFT.
       STA   QDRNT
       TXA
       AND   #$F
       TAX
       LDY   COS,X SAVE COS AND SIN
       STY   DXL VALS IN DXL AND DY.
       EOR   #$F
       TAX
       LDY   COS+1,X
       INY
       STY   DY
DRAW2  LDY   HNDX BYTE INDEX FROM
       LDX   #$0 HI-RES BASE ADR.
       STX   COLLSN CLEAR COLLISION COUNT.
       LDA   (SHAPEL,X) 1ST SHAPE DEF BYTE.
DRAW3  STA   SHAPEX
       LDX   #$80
       STX   EL EL,EH FOR FRACTIONAL
       STX   EH L,R,U,D VECTORS.
       LDX   SCALE SCALE FACTOR.
DRAW4  LDA   EL
       SEC   IF FRAC COS OVFL
       ADC   DXL THEN MOVE IN
       STA   EL SPECIFIED VECTOR
       BCC   DRAW5 DIRECTION.
       JSR   LRUD1
       CLC
DRAW5  LDA   EH IF FRAC SIN OVFL
       ADC   DY THEN MOVE IN
       STA   EH SPECIFIED VECTOR
       BCC   DRAW6 DIRECTION
       JSR   LRUD2
DRAW6  DEX   LOOP ON SCALE
       BNE   DRAW4 FACTOR.
       LDA   SHAPEX
       LSR   ; NEXT 3-BIT VECTOR
       LSR   ; OF SHAPE DEF.
       LSR
       BNE   DRAW3 NOT DONE THIS BYTE.
       INC   SHAPEL
       BNE   DRAW7 NEXT BYTE OF
       INC   SHAPEH SHAPE DEFINITION.
DRAW7  LDA   (SHAPEL,X)
       BNE   DRAW3 DONE IF ZERO.
       RTS

*  HI-RES GRAPHICS SHAPE EX-OR SUBR
*
* EX-OR SHAPE INTO SCREEN.
*
* ROT = 0 TO 3 (QUADRANT ONLY)
* SCALE IS USED
*
XDRAW  STX   SHAPEL SHAPE DEFINITION
       STY   SHAPEH POINTER.
XDRAW1 TAX
       LSR   ; ROT ($0-$3F)
       LSR
       LSR   ; GDRNT 0=UP, 1=RT,
       LSR   ; 2=DWN, 3=LFT.
       STA   QDRNT
       TXA
       AND   #$F
       TAX
       LDY   COS,X SAVE COS AND SIN
       STY   DXL VALS IN DXL AND DY,
       EOR   #$F
       TAX
       LDY   COS+1,X
       INY
       STY   DY
XDRAW2 LDY   HNDX INDEX FROM HI-RES
       LDX   #$0 BASE ADR.
       STX   COLLSN CLEAR COLLISION DETECT
       LDA   (SHAPEL,X) 1ST SHAPE DEF BYTE.
XDRAW3 STA   SHAPEX
       LDX   #$80
       STX   EL EL,EH FOR FRACTIONAL
       STX   EH L,R,U,D, VECTORS.
       LDX   SCALE SCALE FACTOR.
XDRAW4 LDA   EL
       SEC   IF FRAC COS OVFL
       ADC   DXL THEN MOVE IN
       STA   EL SPECIFIED VECTOR
       BCC   XDRAW5 DIRECTION
       JSR   LRUDX1
       CLC
XDRAW5 LDA   EH IF FRAC SIN OVFL
       ADC   DY THEN MOVE IN
       STA   EH SPECIFIED VECTOR
       BCC   XDRAW6 DIRECTION +90 DEG.
       JSR   LRUD2
XDRAW6 DEX   LOOP ON SCALE
       BNE   XDRAW4 FACTOR.
       LDA   SHAPEX
       LSR   ; NEXT 3-BIT VECTOR
       LSR   ; OF SHAPE DEF.
       LSR
       BNE   XDRAW3
       INC   SHAPEL
       BNE   XDRAW7 NEXT BYTE OF
       INC   SHAPEH SHAPE DEF.
XDRAW7 LDA   (SHAPEL,X)
       BNE   XDRAW3 DONE IF ZERO.
       RTS

*  ENTRY POINTS FROM APPLE-II BASIC
BPOSN  JSR   PCOLR POSN CALL, COLR FROM BASIC
       STA   HCOLOR
       JSR   GETY0 Y0 FROM BASIC.
       PHA
       JSR   GETX0 X0 FROM BASIC.
       PLA
       JSR   HPOSN
       LDX   BXSAV
       RTS
BPLOT  JSR   BPOSN PLOT CALL (BASIC).
       JMP   HPLOT1
BLIN1  LDA   HNDX
       LSR   ; SET HCOLOR1 FROM
       JSR   PCOLR BASIC VAR COLR.
       JSR   HPOSN3
BLINE  JSR   GETX0 LINE CALL, GET X0 FROM BASIC
       TXA
       PHA
       TYA
       TAX
       JSR   GETY0 Y0 FROM BASIC
       TAY
       PLA
       JSR   HLIN
       LDX   BXSAV
       RTS
BGND   JSR   PCOLR BACKGROUND CALL
       JMP   BKGND0

*  DRAW ROUTINES
BDRAW1 JSR   BPOSN
BDRAW  JSR   BDRAWX DRAW CALL FROM BASIC.
       JSR   DRAW
       LDX   BXSAV
       RTS
BXDRW1 JSR   BPOSN
BXDRAW JSR   BDRAWX EX-OR DRAW
       JSR   XDRAW FROM BASIC.
       LDX   BXSAV
       RTS
BDRAWX STX   BXSAV SAVE FOR BASIC.
       LDY   #$32
       JSR   PBYTE SCALE FROM BASIC.
       STA   SCALE
       LDY   #$28
       JSR   PBYTE ROT FROM BASIC.
       PHA   SAVE ON STACK.
       LDA   SHAPXL
       STA   SHAPEL START OF
       LDA   SHAPXH SHAPE TABLE.
       STA   SHAPEH
       LDY   #$20
       JSR   PBYTE SHAPE FROM BASIC.
       BEQ   RERR1
       LDX   #$0
       CMP   (SHAPEL,X) > NUM OF SHAPES?
       BEQ   BDRWX1
       BCS   RERR1 YES, RANGE ERR.
BDRWX1 ASL
       BCC   BDRWX2
       INC   SHAPEH
       CLC
BDRWX2 TAY   SHAPE NO. * 2.
       LDA   (SHAPEL),Y
       ADC   SHAPEL
       TAX   ADD 2-BYTE INDEX
       INY   TO SHAPE TABLE
       LDA   (SHAPEL),Y START ADR
       ADC   SHAPXH (X LOW, Y HI).
       TAY
       PLA   ROT FROM STACK.
       RTS

*  BASIC PARAM FETCH SUBR'S
PCOLR  LDY   #$16
PBYTE  LDA   (LOMEML),Y
       BNE   RERR1 GET BASIC PARAM.
       DEY   (ERR IF >255)
       LDA   (LOMEML),Y
RTSB   RTS
GETX0  STX   BXSAV SAVE FOR BASIC.
       LDY   #$5
       LDA   (LOMEML),Y X0 LOW-ORDER BYTE.
       TAX
       INY
       LDA   (LOMEML),Y HI-ORDER BYTE.
       TAY
       CPX   #$18
       SBC   #$1 RANGE ERR IF >279
       BCC   RTSB
RERR1  JMP   RNGERR
GETY0  LDY   #$D OFFSET TO Y0 FROM LOMEM
       JSR   PBYTE GET BASIC PARAM Y0.
       CMP   #$C0 (ERR IF >191)
       BCS   RERR1
       RTS

*  SHAPE TAPE LOAD SUBROUTINE
SHLOAD STX   BXSAV SAVE FOR BASIC.
       JSR   ACADR READ 2-BYTE LENGTH INTO
       JSR   READ BASIC ACC
       LDA   #$00 ;START OF SHAPE TABLE IS $0800
       STA   A1L
       STA   SHAPXL
       CLC
       ADC   ACL
       TAY
       LDA   #$08 ;HIGH BYTE OF SHAPE TABLE POINTER.
       STA   A1H
       STA   SHAPXH
       ADC   ACH
       BCS   MFULL1 NOT ENOUGH MEMORY.
       CPY   PPL
       PHA
       SBC   PPH
       PLA
       BCS   MFULL1
       STY   A2L
       STA   A2H
       INY
       BNE   SHLOD1
       ADC   #$1
SHLOD1 STY   LOMEML
       STA   MOMEMH
       STY   PVL
       STA   PVH
       JSR   RD2BIT
       LDA   #$3 .5 SECOND HEADER.
       JSR   READX1
       LDX   BXSAV
       RTS
MFULL1 JMP   MEMFUL