Wow, very simple code to produce pattern. Didn't thought of that before.
Just tried a similar programm on amstrad CPC.
10 k% = 47 + 45 * INT(RND*2):PRINT CHR$(k%);:GOTO 10
Works like a charm, though the characterset of CPC is different, they live one line or row of pixels empty so that nearby or above characters don't stick together visually, so the labyrinth pattern is not looking so solid. But this could be solved with the SYMBOL command where one can introduce his own character sets. Gonna try this one next.
p.s. You are right, I miss those times where each home computer was one solid thing with it's own shape and personality and most were booting basic at start up. Everyone was learning programming then and the computer magazines offered pages with code and tutorials. And everything was more simple.