Developer and vintage computer enthusiast Jeff Epler has written a guide to getting a crisp and clean HDMI-compatible signal out of computers with analog video capabilities - connecting a classic Xerox 820 to modern displays using the Adafruit Feather RP2040 and CircuitPython.
The Xerox 820 is a desktop computer released in 1981 and designed to run Digital's CP/M 2.2 operating system. The processor PCB is located inside the CRT unit and includes a Z80A, 64 KB of RAM, and a boot ROM that allows booting from any of the supported external drives in 8-bit mode.
The obsolete Xerox 820 computer connector is designed to output to CRT monitors and is completely incompatible with any ports you might find on modern monitors, which means the only way to run CPU PCBs is to find the same TTL monitor or convert it to something more modern.
Eplera takes the latter approach in its project.
Project description on the Adafruit Learn portal: https://learn.adafruit.com/vintage-computer-to-dvi-with-feather-dvi-circuitpython/overview
The obsolete Xerox 820 computer connector is designed to output to CRT monitors and is completely incompatible with any ports you might find on modern monitors, which means the only way to run CPU PCBs is to find the same TTL monitor or convert it to something more modern.
Eplera takes the latter approach in its project.
Project description on the Adafruit Learn portal: https://learn.adafruit.com/vintage-computer-to-dvi-with-feather-dvi-circuitpython/overview