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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