The Xerox Alto was the first computer designed to support an operating system based on a graphical user interface (GUI), later using the desktop metaphor.
The first machines were introduced on 1 March 1973, a decade before mass market GUI machines arose.
The rat-infested Digibarn monitor isn’t even meant to be connected to an Alto, and does not work either. But we find a way to retrofit it to the Alto, and find that a tiny light bulb buried in the high voltage circuitry is the cause of the failure. More details about what a bulb is doing in the circuit on Ken’s blog (and don’t believe the inane comments, it is NOT used a fuse): http://www.righto.com/2017/10/inside-…
All of the switching power supplies from our Xerox Alto from the Digibarn are bad. All of them! And the main LH Research MIghty Mite 5V/60A power supply is putting up a real fight. By the time I start this video, we are a good week into troubleshooting it, with a growing pile of bad parts and no end in sight.