VIC Video Revisited

I made some modifications to Jim Butterfield's program in "Visiting The VIC-20 Video, Part 4" (COMPUTE!, August 1983) that I think your readers will be interested in. Although the program is a little slow, the patterns that result are remarkable.

The program is short, but because of the loops, it runs for a while. To get some really interesting three-dimensional patterns, try inputs with a value of 1.02, 1.03, 1.04, etc. The input sets a step value for line 600. An input of 2 will give a gray field.

William B. Broome

100 POKE56,22:CLR
105 INPUT"{CLR}PATTERN  #";C
110 POKE36869,222
120 POKE36866,144
130 POKE36867,32
200 FORJ=6144TO8191
210 POKEJ, 0:NEXTJ
300 FORJ=0TO255
310 POKEJ+5632,J
320 NEXTJ
330 FORJ=37888TO38911
340 POKEJ.0:NEXTJ
600 FORJ=6100TO8800 STEPC
610 X=128
620 F0RK=JTOJ+7
630 POKEK,PEEK(K)ORX
640 X=X/2
650 NEXTK,J
700 GOTO700

Try adding STEP C to line 620 as well, to get another interesting effect.