Table of Contents
Good day in the mailbox... the Willy Wonka CPU boards have landed on the bench.
CPU is the 3K RAM half of the Willy Wonka family for the VIC-20. It drops 3K of RAM into the BLK0 region ($0400–$0FFF), the gap the stock machine leaves wide open. Address decoding is handled by a GreenPAK SLG46533V, and the board connects to the VIC-20 motherboard via FFC cable so the host PCB stays untouched.
CR and CPU are independent projects. You can fit either one on its own, or both together for the full Willy Wonka feature set.
Bring-up plan:
- Visual inspection of the assembled boards.
- Power up on the bench and check rails before connecting to a host machine.
- Fix the GreenPAK configuration. The current NVM image has a few known issues that need to be sorted before the decoding behaves the way the schematic intends.
- Install in a VIC-20 and walk through the functional checks.
Once the CPU board is solid, the next experiment is to fit logic for running the 65C02 in fast mode at 8 MHz when accessing on-board memory ... that is Kernal, BASIC and RAM. The IO area stays at the native bus speed, and BLK0 is handled with write-through so the rest of the machine still sees what it expects. The idea is to get the CPU off the leash for everything that doesn't need to talk to the outside world, while keeping timing-sensitive accesses untouched.
More on that once the baseline board has proven itself. Bring-up notes to follow.