SCN68681C chips have been discontinued for years.
It took a long time to find a source, and on the first try I managed to get NOS (new old stock) from warehouse stock.
Condition is excellent: clean markings and fully working parts.

The chip contains undocumented instructions that still execute consistently on real hardware. Developers discovered them by experimentation, and some are faster or more powerful than official ones. They’re risky — but legendary.

Unlike many CPUs of its era, the 6502 executes instructions mostly through hardwired control logic. This makes its behavior very predictable and also why cycle-exact programming and demos are even possible.

The 6502 has a tiny transistor count compared to its competitors, yet delivers impressive performance per clock. Fewer registers, simple addressing modes, and tight timing made it fast where it mattered — real code on real hardware.

Apple I and II, Commodore PET and C64, Atari 2600, and the NES all ran on the 6502 or its variants. If you used a home computer or console in the late 70s–80s, chances are it had a 6502 at its core.

Fixed the contact temporarily for testing — and the system booted immediately.
Lesson learned:
check IC socket pins, not just solder joints.
A single bad contact can make a computer look dead.

First thought: RESET button.
Desoldered it — no change.
While reflashing the PLD, I noticed the real issue:
a bad IC socket pin — no proper contact at all.

At launch, there will be two kits: - rosco_m68k — a single-board computer based on the Motorola 68010 - rosco_6502 — a single-board computer built around the W65C02S8P-10