ContrAlto

The complete schematics of the Xerox Alto are on Bitsavers. I don't think photos would help a lot with generating a PCB, since the chips cover much of the wiring. A bigger problem with a Xerox Alto replica is the wire-wrapped backplane. It would be a pain to redo that by hand. For most purposes, you'd be better off using the ContrAlto emulator. Schematic link: http://bitsavers.org/pdf/xerox/alto/schematics ContrAlto link: https://github.com/livingcomputermuseum/ContrAlto

ContrAlto won't work, since it's the name of the Alto simulator written by the Living Computers Museum. (It's a very good simulator, letting you see what happens right down to the microcode.) I'm going to use XeroDay for the attack name. https://github.com/livingcomputermuseum/ContrAlto

The Alto hardware manual explains how the microcode works (see sections 2 and 9 and try to memorize Figure 1). For examples, see the existing Alto microcode. The subsystem manual p90 describes the MU microcode assembler and the syntax. See also RPRAM in the subsystem manual that describes how to load microcode into control RAM. I haven't seen anything like a howto/tutorial for microcode in the Alto documentation. http://bitsavers.informatik.uni-stuttgart.de/pdf/xerox/alto/... http://bitsavers.informatik.uni-stuttgart.de/pdf/xerox/alto/... http://www.mirrorservice.org/sites/www.bitsavers.org/pdf/xer... If you want to try this stuff out for yourself (and don't have an Alto handy), use the ContrAlto emulator: https://github.com/livingcomputermuseum/ContrAlto

Funny you should mention that, because the Living Computer Museum wrote a high-quality emulator (ContrAlto) for the Alto. It's super-accurate, even emulating the microcode and hardware, and runs at the speed of the live machine. It includes a debugging mode that lets you examine machine state and step through machine instructions and microcode. Source: https://github.com/livingcomputermuseum/ContrAlto ContrAlto was very helpful while getting the real Alto running, and I also use it for developing software such as the Mandelbrot. I wrote a guide to getting started with ContrAlto: http://www.righto.com/2016/10/simulating-xerox-alto-with-con...