Yeep!Eep!Eep!Program generates patterns for the C64 by manipulating the VIC registers. It assigns alternate character sets, through which are displayed what happens to be in RAM at the time, or what was on the screen just before the program ran.
For those who want to run this on the C64 using a 1541 or similar, I'll get a disk to you -- just reach out.
For everyone else, use VICE or another C64 emulator.
Download YEEP as a disk image. The name of the program is "YEEP01". If you're using drive 8 (in VICE, for instance), type: