In this episode of projectCD.Chronicles, the focus shifts to a clever C64 autorun trick—a machine language routine that hijacks the standard boot process of the Commodore 64. By intercepting the warm start behavior, it prevents BASIC programs from auto-executing immediately after loading, giving users control over when the program starts.
The C64 autorun trick works by rewriting specific memory locations and interrupting the keyboard buffer with preloaded characters: R, U, and return—essentially simulating a typed “RUN” command. This lets users sneak a peek at the code listing before execution, which is especially handy for BASIC programs with hidden source code. It’s not just a workaround; it’s a control shift—literal and figurative—over how programs behave post-load.
The routine stems from an article by Michele Maggi, published in issue 39 of Commodore Computer Club. The original listing builds on earlier work from issue 34 but improves usability. Once loaded, the machine code nestles itself between memory locations $0302 and $0800, modifies warm start vectors, and disables interruptions like RESTORE and RUN/STOP. That’s the sleight of hand: a manual “RUN” typed in your place without touching the keyboard.
The video concludes with a preview of disk images, CBM Program Studio recreations, and test programs, encouraging viewers to recreate and share these routines to preserve software from vintage publications. This C64 autorun trick isn’t just technical tinkering—it’s part of keeping 8-bit software alive and accessible.
