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Vintage Adventures - MOS 6502 - Part 2

Sat, 28 Mar 2026 00:00:00 +0000

In Part 1 we covered the MOS 6502’s architecture, walked through its instruction set, and decoded a small test program by hand. That gave us the basic structure of a CPU emulator:

while running:
    opcode = memory[PC]
    instruction = decode(opcode)
    instruction.execute(operands)
    PC += instruction.length

The pseudocode is clean, but there are obvious pieces missing. We need to define the decode function, implement the execution logic for each instruction, and emulate both the memory and the registers. Time to turn that sketch into real code.

Vintage Adventures - MOS 6502 - Part 1

Sat, 21 Mar 2026 00:00:00 +0000

This next set of posts are a bit of a distraction from security themes articles, and we’ll explore some vintage computer hardware.

The MOS 6502 is a classic CPU that drove the home computer revolution in the late 1970s and early 1980s. Along with the Zilog Z80, it brought computing to the masses. The 6502 powered some of the most iconic machines of the era, the Apple II, the Commodore 64, the Atari 2600, and the British-built BBC Micro, among others. It even found its way into the original Nintendo Entertainment System (as the Ricoh 2A03, a modified 6502).