LogicAnalyzers

HP Reference Manuals:

• Inverse Assembler Manual for 1650 Logic Analyzers

Tutorials on HP Logic Analyzers:

• NSDU HP 1652B User Info - (local cache)
• Dartmouth Engs31 tutorial
• MIT 6.111 tutorial

2014 update.. inexpensive USB logic analyzers are now available for $25 or less!

• sigrok - Open source firmware and frontend software for signal analysis. Runs on lots of different kinds of hardware.