Jump!
Entry posted by Xuel
3,607 views
Jump!!!
An entry into the NOMAM 2014 BASIC Ten-Liners Contest
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Screenshots and Video
Objective
Avoid falling off the bottom of the screen or getting crushed at the top. Move left and right with the joystick. Press trigger to start.
Features
- Smooth scrolling at 44 FPS
- In-game music
- Physics simulation
- Hiscore and splash screen
- All in Nine lines of Turbo Basic
Limitations
Unfortunately it runs much slower on an NTSC machine.
Code
Note that special ATASCII characters are not shown.
Line 0
0 PL=ADR("U U *U*U* ***** * U U U U y`Q< y`HQ@5(-5@QH<-#(5@Q[H5-(5@Q"):GOSUB 8:POKE 752,1
PL - Level and music data. Call screen initialization routine. Turn off cursor.
Line 1
1 ? "SCORE:",S;:IF S>H:H=S:? " GREAT!";:ENDIF :? "HISCORE:",H:? "":? " ";:WHILE STRIG(0):WEND
Score and splash screen.
Line 2
2 SP=$E2A0:PM=$A200:HP=$D000:SC=$BE70:S2=SC+10:CC=200:SB=SC+190:VS=$D405:POKE $D01D,2:C=1.4:Y=20:A=0.2:G=0.2:GOSUB 8
Tell GTIA to fetch player data from ANTIC via GRACTL, $D01D. Call screen initialization routine.
SP - Pointer to circle in character set ROM.
PM - Pointer to Player/Missle data. Not properly allocated.
HP - HPOSP0 Player 0 X position register
SC - Start of screen data. Blindly assume OS always puts it here.
S2 - Pointer to second line of screen
CC - Size of screen in bytes
SB - Bottom of screen where new lines will be drawn
VS - VSCROL fine vertical scrolling register
C - Unused
Y - Y position
A - horizontal acceleration
G - gravity
Line 3
3 POKE 559,$2E:CO=$D004:HC=$D01E:X=100:N=%0:M=%0:S=%0:SOUND 0,0,10,10:P=$D200:POKE 752,1:T=PL+52:R=$FE46:E=R+$FF
Set DMACTL. Initialize velocity. Set score to 0. Prepare sound channel. Turn off cursor.
CO - P0PF collision register.
HC - HITCLR collision clear.
P - AUDF1 POKEY channel 1 period register.
T - Pointer to music period data.
R - Pointer to ROM lookup tables used as level data.
E - End of level data.
Line 4
4 POKE 77,0:DO :J=STICK(%0):IF J<8:IF M<%1 THEN M=M+A:ELSE :IF J<13 AND M>-%1 THEN M=M-A:ENDIF
Start game loop. Check joystick. Set X velocity accordingly.
Line 5
5 IF PEEK(CO):N=-0.6:POKE HC,%0:ELSE :IF N<1.5:N=N+G:ENDIF :ENDIF =X+M:Y=Y+N:MOVE SP,PM+Y,9:POKE HP,X
Check collision. Set Y velocity accordingly. Add velocity to position. Plot ball.
Line 6
6 IF Y>130 OR Y<9 OR X>250 OR X<5:SOUND:GOTO 1:ENDIF :F=F+%1:PAUSE %0:IF F>7:POKE VS,%0:MOVE S2,SC,CC:IF (S&7)=%0
Check for death. Wait for VSYNC with PAUSE 0. Fine scrolling. Coarse scrolling.
Line 7
7 MOVE PL+PEEK(R)&31,SB,10:R=R+8:IF R>E:R=R-$FF:ENDIF :ENDIF :F=%0:MOVE T+(S&31),P,%1:S=S+%1:ENDIF :POKE VS,F:LOOP
Draw new platforms. Use OS ROM tables as level data. Play music. Add points to score. Set VSCROL. Loop.
Line 8
8 GRAPHICS 3:D=$BE54:POKE D-3,$68:POKE D,$28:MOVE D,D+1,17:POKE 623,1:POKE 704,$38:POKE $D407,PM/256:MOVE SC,PM,128:RETURN
Screen configuration routine. Modifies OS display list in-place to include VSCROL attributes. Incidentally sets GPRIOR, COLPM0, PMBASE and clears PMG bitmap.
Thanks
This game was inspired by two great games, Man Goes Down and Downfall.
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5
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