UART FIXED! I hadn't soldered the oscillators ground line, so the UART chip had no clock signal. Duh. Anyways, I had written an OS with the help of an emulator I think starting about a year ago. Here is a branch of it running on my Z80 computer:

Still a long ways to go. Next step: graphics!

You see, the NGT20 is one of a line of video-card-like devices I made. My Z80 computer has been designed for a long time to be compatible with one of its unnamed relatives. I just got a CF card to IDE adapter and a CF card for files. Also, I have an RTC chip on the way so I can multitask. Lots of things happening moving forward!