How microcontrollers work: Simple Microcontroller Series - PIC10F200 and Assembly

How CPUs work: See How a CPU Works

Hardware Hacking Tutorial

Radio hacking with software defined radio and more: Radio Hacking: Cars, Hardware, and more! - Samy Kamkar

USB hacking: Facedancer 2.0 Next Generation USB Hacking

How To Find The JTAG Interface - Hardware Hacking Tutorial

Extracting Firmware from External Memory via JTAG