Monotron: Making a 80s style computer with a $20 dev kit (rustfest18)

I missed the simplicity of of computers like the C64 and the Apple 2 and I wondered if I could recreate something like that, but using the Cortex M4 devboard on my desk and a handful of resistors. Can you generate VGA without a video chip? Can you render text without enough RAM for a framebuffer? Can you read from a PS/2 keyboard? Can you do it all in Rust, and run tests on an actual PC? Will it run fast enough to be useful? about this event: https://c3voc.de