Jeri Ellsworth - Magnetic Logic Gates https://www.youtube.com/watch?v=p7SkE5pERtA

School House Rock - Little 12 Toes https://www.youtube.com/watch?v=_uJsoZheTR4

Z80 - 4 Bit ALU in an 8 bit processor http://www.righto.com/2013/09/the-z-80-has-4-bit-alu-heres-how-it.html

Z80 - An Oral History http://archive.computerhistory.org/resources/text/Oral_History/Zilog_Z80/102658073.05.01.pdf

Mask Programmed Forgery http://zeptobars.ru/en/read/FTDI-FT232RL-real-vs-fake-supereal

Homebrew Cray http://www.chrisfenton.com/homebrew-cray-1a/

Relay Computer http://web.cecs.pdx.edu/~harry/Relay/index.html

Underflow hazard in Civilization http://kotaku.com/why-gandhi-is-such-an-asshole-in-civilization-1653818245

CompArch on a Comet http://www.cpushack.com/2014/11/12/here-comes-philae-powered-by-an-rtx2010/