Here’s are all the 30 classic patterns (as described by Sébastien Truchet in “Mémoire sur les combinations” in 1704) on the PET:
https://masswerk.at/pet/?prg=truchet-pet&screen=white
(Port of an original C64 program by Robin from the “8-bit Show and Tell” YT channel; press any key to advance to the next pattern. – It’s a bit nicer on the PET, since the characters are rendered at somewhat better resolution as compared to the C64, which features a bolder font.)
Here’s a ZX Spectrum version that scrolls infinitely:
10 FOR n=0 TO 31: PRINT " ▌▄"(1+RND);: NEXT n: POKE 23692,255: GO TO 10
And a ZX81 version that does the same:
10 PRINT AT 21,0;
20 FOR N=0 TO 31
30 PRINT " ▌▄"(1+RND);
40 NEXT N
50 SCROLL
60 GO TO 20
Very nice. Since the TRS-80 supports RND(N) you can get away with:
0 PRINTCHR$(110+RND(2)*39);:GOTO
And throwing in GOTO defaulting to line 0 which I think will work on the C-64 as well.
This discussion reminded me of a game I made for the MSX that also used this nice “10 PRINT”.
Here’s the link if you want to play or see the code: MazeRun by OrbDream
I forgot to attach the image:
