53248



     20   N = 100: POKE HPOS,N: POKE 53261
        ,255
     30   IF STICK(0) = 11 THEN N = N - 1:
         POKE HPOS,N: PRINT N
     40   IF STICK(0) = 7 THEN N = N + 1:
        POKE HPOS,N: PRINT N
     50   GOTO 30

     There are no vertical position registers for P/M graphics, so you
     must use software routines to move players vertically. One idea for
     vertical motion is to reposition the player within the P/M region
     rather than the screen RAM. For example, the program below uses
     a small machine language routine to accomplish this move:

     1 REM LINES 5 TO 70 SET UP THE PLAYER
     5 KEEP=PEEK(106)-16
     10 POKE 106,KEEP:POKE 54279,KEEP
     20 GRAPHICS 7+16:POKE 704,78:POKE 559
        ,46:POKE 53277,3
     30 PMBASE=KEEP*256
     40 FOR LOOP=PMBASE+512 TO PMBASE+640:
        POKE LOOP,0:NEXT LOOP:REM CLEAR OU
        T MEMORY FIRST
     50 X=100:Y=10:POKE 53248,X
     60 FOR LOOP=0 TO 7:READ BYTE:POKE PMB
        ASE+512+Y+LOOP,BYTE:NEXT LOOP:REM
        PLAYER GRAPHICS INTO MEMORY
     70 DATA 129,153,189,255,255,189,153,1
        29
     80 REM LINES 100 TO 170 SET UP MACHIN
        E LANGUAGE ROUTINE
     100 DIM UP$(21),DOWN$(21):UP=ADR(UP$)
         :DOWN=ADR(DOWN$)
     110 FOR LOOP=UP TO UP+20:READ BYTE:PO
         KE LOOP,BYTE:NEXT LOOP
     120 FOR LOOP=DOWN TO DOWN+20:READ BYT
         E:POKE LOOP,BYTE:NEXT LOOP
     130 DATA 104,104,133,204,104,133,203,
         160,1,177
     140 DATA 203,136,145,203,200,200,192,
         11,208,245,96
     150 DATA 104,104,133,204,104,133,203,
         160,10,177
     160 DATA 203,200,145,203,136,136,192,
         255,208,245,96
     200 REM VERTICAL CONTROL
     210 IF STICK(0)=14 THEN GOSUB 300