Adding integers with hundreds of digits using string manipulation in Commodore BASIC. When your numbers are too big for Wolfram Alpha.

Starting a year-long project to reverse engineer and create a drop-in FPGA replacement for the VIC-20’s 6560/6561 video chip.

Before and after comparison of S-Video mod results on the Vicky-20 PAL replica board. Dramatic improvement over composite output.

Extending Commodore BASIC with a PRINT AT command using machine language, then using it to visualize the 100 door problem.

Visualizing the poor randomness of RND() on the Commodore 64 and 128 compared to the PET and Plus/4. Clear patterns emerge when you plot the output.

Generating all 362,880 permutations of 1-9 the hard way: understanding algorithms instead of relying on library functions. Implementations in Python, BASIC, and 6502 assembly.

Attempting the annual Advent of Code challenge on vintage 8-bit computers. Completing about 60% of puzzles on Commodore hardware.

Calculating Pi on a Tandy Color Computer 2 with basic (non-Extended) BASIC. Working around the missing exponent function.

Solving the classic 100 door problem with visual output on multiple vintage systems: VIC-20, C64, PET, Atari, and Color Maximite.

How to load and run Commodore 64 BASIC programs on a PET. Working around the PET’s lack of program relocation.

Generating pseudo-random numbers with the Lagged Fibonacci Sequence on the VIC-20. Building reusable BASIC subroutines for the cipher toolbox.

How to perform modulo operations in Commodore BASIC 2 without a cartridge. A one-line solution for VIC-20 and C64.