Collection of random useful URL's

http://acoptex.com/project/8003/raspberry-basics-project-29a-raspberry-pi-zero-w-board-raspberry-pi-gpio-pinout-at-acoptexcom/

https://pinout.xyz/

https://payatu.com/using-rasberrypi-as-poor-mans-hardware-hacking-tool

https://ralimtek.com/raspberry%20pi/electronics/software/raspberry_pi_secondary_sd_card/

https://github.com/superzerg/logic-analyzer
https://sigrok.org/wiki/PulseView