1000 ! FLD LINE BOUNCE
1010 ! BY ANDY PARTRIDGE
1020 ! CREDIT ME IF YOU USE IT-OR ELSE!
1030 !
1040 !
1050 *=49152
1060 !
1070 LDA #1
1080 STA $D021
1090 STA 646
1100 JSR $E544  !<CLEAR SCREEN
1110 LDX #0     !<CLEAR RAM TO AVOID
1120 STX $3FFF  ! GARBAGE IN FLD'D AREA
1130 !
1140 LDA #<TEXT !<DISPLAY TEXT ON
1150 LDY #>TEXT ! THE SCREEN
1160 JSR $AB1E
1170 !
1180 SEI
1190 LDA #$7F
1200 STA $DC0D ! SET INTERUPTS
1210 LDA $DC0D
1220 LDA #<IRQ
1230 STA $314
1240 LDA #>IRQ
1250 STA $315
1260 LDA #1
1270 STA $D01A
1280 LDA $D011
1290 AND #$7F
1300 STA $D011
1310 LDA #$32  ! <- ALTER THIS RASTER
1320 STA $D012 ! TRIGGER NUMBER FOR
1330 LDA #1    ! POSTITION OF BOUNCE
1340 STA $D019
1350 CLI
1360 RTS
1370 !
1380 IRQ !
1390 !
1400 LDX #$4 ! WAIT A LITTLE BIT !
1410 HH DEX  ! (REMOVE THIS AND THE
1420 BNE HH  ! TOP LINE FLICKERS ON/OFF)
1430 !
1440 LDX POS1 ! GET NO. OF LINES TO FLD
1450 !
1460 D1 LDA $D012  !<GET CURRENT LINE
1470 T1 CMP $D012  !<STILL THERE?
1480 BEQ T1        ! IF YES,WAIT
1490 AND #$07      !<IF NOT,FLD LINE
1500 ORA #$10      ! DOWN.WHY IT WORKS?
1510 STA $D011     ! WHO KNOWS!
1520 DEX           !<FINISHED?
1530 BNE D1        ! IF NOT,CONTINUE!
1540 !
1550 LDY #0
1560 JU LDX DTAB,Y
1570 L2 DEX
1580 BNE L2
1590 LDA CTAB,Y    !<THIS PART JUST
1600 STA $D020     ! DISPLAYS THE GREEN
1610 STA $D021     ! BAR UNDER THE TEXT.
1620 INY           ! (LIKE PROGRAM 1)
1630 CPY #19
1640 BNE JU
1650 !
1660 LDX POS2
1670 !
1680 DP1 LDA $D012 ! AND DO THE FLD
1690 TP1 CMP $D012 ! AGAIN BELOW TO
1700 BEQ TP1       ! COMPENSATE FOR THE
1710 AND #$07      !<TOP ONE...
1720 ORA #$10      ! OTHERWISE THE
1730 STA $D011     ! WHOLE SCREEN WOULD
1740 DEX           ! GO UP AND DOWN!
1750 BNE DP1       ! TRY DELETING THIS!
1760 !
1770 LDA #$01
1780 STA $D019
1790 LDA #$1B      !<RESET $D011 AFTER
1800 STA $D011     ! OUR FIDERLING !
1810 JSR BOUNCE    !<CALCULATE BOUNCE
1820 JMP $EA31     !<AND FINISH!
1830 !
1840 DTAB BYT 8,8,8,8,8,8,8,1,8,8,8,8,8,8,8,1,8,8,8 !<DELAYS FOR MIDDLE BIT!
1850 CTAB BYT 9,5,13,0,0,0,0,9,5,5,9,0,0,0,0,13,5,9,0 !<COLOURS FOR MIDDLE BIT!
1860 !
1870 BOUNCE !
1880 !
1890 HUP INC POSC
1900 LDX POSC
1910 CPX #123     !<ROUTINE THAT READS
1920 BNE NO95     ! THE VALUES FROM THE
1930 LDA #255     ! SINUS TABLE FOR THE
1940 STA POSC     ! FLD ROUTINE.
1950 JMP HUP
1960 NO95 LDA SINUS,X
1970 SEC
1980 ADC #5
1990 STA POS1
2000 LDA #85
2010 SBC POS1
2020 STA POS2
2030 RTS
2040 !
2050 POS1 BRK
2060 POS2 BRK
2070 POSC BRK
2080 !
2090 SINUS !
2100 BYT $1E,$1C,$1B,$19,$18,$16,$15,$13,$12,$10,$0F,$0E,$0D,$0B,$0A,$09
2110 BYT $08,$07,$06,$05,$04,$03,$03,$02,$02,$01,$01,$00,$00,$00,$00,$00
2120 BYT $00,$00,$00,$00,$00,$01,$01,$02,$02,$03,$04,$04,$05,$06,$07,$08
2130 BYT $09,$0A,$0C,$0D,$0E,$0F,$11,$12,$13,$15,$16,$18,$19,$1B,$1C,$1E
2140 BYT $1F,$21,$22,$24,$25,$27,$28,$29,$2B,$2C,$2D,$2F,$30,$31,$32,$33
2150 BYT $34,$35,$36,$37,$38,$38,$39,$3A,$3A,$3A,$3B,$3B,$3B,$3B,$3B,$3B
2160 BYT $3B,$3B,$3B,$3A,$3A,$39,$39,$38,$37,$36,$36,$35,$34,$33,$32,$30
2170 BYT $2F,$2E,$2D,$2B,$2A,$29,$27,$26,$24,$23,$21,$20,$1F
2180 !
2190 !   ^  TABLE OF VALUES FOR BOUNCE
2200 !   !  (CALCULATED IN BASIC)
2210 !
2220 TEXT !
2230 BYT " DREAMS BEYOND THE YOUNG UNDERSTANDING! "
2240 BYT "(C) ANDY PARTRIDGE  (THE WORD MAGICIAN!)",0
2250 !
2260 !   ^  THE TEXT PRINTED ON THE
2270 !   !  SCREEN...
2280 !