> Yeah. A 1980s era Microsoft DOS computer capability running on a $1.75 microcontroller is exactly what I want, on one hand. I'm not greedy or needy, after all. A microcontroller with WiFi connectivity built in (or easily attached, imported, or included) for building a networked system of these smart little computers and hardware part controllers too. Like, a washing machine that sends a "done washing" message to a headless server sitting in the home.
OK, that's an ESP8266, then. Here's a module for $2.11.
That's the starting point. If you want to design boards, you can put down ESP8266 castellated modules (easy) or the ESP8266 chip itself (somewhat harder).
Because of issues with electronics supply chains, often complete boards are cheaper than you can buy the modules and chips at low quantities (things are really optimized to sell a thousand units or more). Even buying blank keycaps at low quantities was very expensive compared to finished products of printed sets of keys.
OK, that's an ESP8266, then. Here's a module for $2.11.
https://www.aliexpress.us/item/3256805440432225.html
They're far more capable than you're describing-- capable of emulating an PC-XT at close to 80% speed. For throwaway stuff you could use micropython.
They're cheaper than thinking about how to use random micros you find.