Now in PDF, the book How to Build a Microcomputer … and Really Understand it, by Sam Creason hosted on the
Retro Computing website
An early book on a 6502 microcomputer. Around the 6502 and parts from the 1979 period.
Interesting is the diode matrix based ‘PROM’.Very well written and gives lots of insight in digital logic.
There are also a number of other older publications on the site.