The PS/2-style port was once about as ubiquitous on PCs as USB connectors are today, and more than a few of us accumulated a fair collection of keyboards and mice that sported the 6-pin mini-DIN plug. They’re not nearly as common today, but when you need one, you need one, so if your stockpile of PS/2 keyboards has dwindled to nothing, you might want to look at rolling your own PS/2 remote keyboard dongle.
That backstory on [Remy Sharp]’s build starts with his acquisition of a neptUNO, a 160€ FPGA retrocomputer that gives you access to just about every Z80 and 6502 computer of yesteryear. While the box supports USB keyboards, [Remy] had trouble getting one to work. So out came a Wemos D1 Mini, which was wired up to a stub of PS/2 cable. The microcontroller is powered by the PS/2 port, and connects to the WiFi network on boot-up and starts a WebSocket server. It also served up a page of HTML, which lets him connect with any device and send keystrokes to the neptUNO. He also added a couple of hardware buttons to the dongle, to access menus on the neptUNO directly. The video below shows it in action.
Perhaps unsurprisingly, [Remy] says he took inspiration for this build from [Ben Eater]’s excellent PS/2 deep dive. We’d like to think he saw that here first, but either way, it’s a valuable reference on how keyboards used to work.
Thanks to [Irregular Shed] for the tip.