rc2014-compat

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 (such as $2 double-sided at JLCPCB).

68b50-dual-serial

Two serial ports, one card. One is connected to the TX/RX lines of the backplane for a TTL-level console port, while the other drives a 9-pin serial port through a MAX232 to control printers, modems, and other RS-232 devices. Most bitrates from 300 bps to 38.4 kbps are independently selectable with jumpers. The card's base I/O address is also jumper-selectable.

This board has its own 2.4576-MHz crystal oscillator, making it independent of CPU speed. By replacing the oscilator with a 3.6864-MHz version, 57.6 and 115.2 kbps can be used.

KiCad configuration notes

In the JLCPCB Tools plugin, import jlcpcb-rotations.csv.