A respin of the RC2014 ecosystem. I don't have any opposition to building things out of SMD parts (in some ways, I find it easier to work with), so some boards might go that way to the extent that parts availability allows. Also, I'd like to keep all board sizes within the 100x100mm limit within which PCB fabs offer their cheapest rates (like $2 double-sided at JLCPCB, for instance).

Available boards will be listed below as I add them. KiCad 6 is required to work with the designs. Make sure to check out the repo with git clone --recursive ... to get the extra KiCad libraries some projects use.

rc2014-template

I took the board file from here and fleshed it out into a full template for use with KiCad. It supports the extended signals (such as NMI, WAIT, and the second clock), but would still need further extension if you want it to support 16-bit CPUs or some of the other extended signals.

6502-cpu-board

The Apple II got me through high school and college; writing software for it was the first computer-related activity that made me money (small amounts in retrospect, but it was a start). I'm far more familiar with the 6502 than the Z80, so it'd be nice to be able to work with one here.

This board is a re-creation of this board, recaptured in KiCad and laid out to fit within the template provided above. The Tindie page provides these resources, which I probably ought to include in this repo somehow:

A long-term goal would be to take the dialect of Microsoft BASIC Apple used in the II and modify it to work here, perhaps with improved graphics from a TMS9918 or one of its successors. The Apple II's monitor would also be nice to have, but while Apple open-sourced Integer BASIC and Microsoft open-sourced its BASIC, I'm less sure about the Apple II monitor. (The Apple I monitor was open-sourced...that's the "WozMon" that's easily located.)

6502-cpu-board-smd

Mostly an adaptation of the preceding. One significant change: the I/O base address can be changed from the default $C000 if desired by cutting and soldering the 8 jumpers near the 74LS688.

z80-cpu-smd

Basically the same as the RC2014 Z80 module, but with a 10-MHz LQFP-44 CPU and a crystal oscillator to run it at that speed.

backplane

A modular backplane that provides 4 slots with 20-mm spacing between them on a 100x100mm double-sided PCB, with USB-C power input, a power-on reset circuit (with reset button), a 4-pin TTL UART connector, and an idiot light that indicates it's receiving power. 50-pin connectors at opposite edges allow daisy-chaining more boards together. Holes for M3 mounting screws are provided. If only the slots and daisy-chaining are needed, all the wiring for those is on the bottom, so you could make those with single-sided PCBs if you want.