IEEE-1284 Standard - PC Parallel Port
ISA Bus
Mac Serial Port Interfacing
Modem Protocols
PC Game Port
PC IDE Drive Interface
PC Keyboard Port - Both AT and PS/2
PC Parallel Port Driver
PC Serial Ports
SCSI FAQ
USB Central - Information, tools, and links to material about the Universal Serial Bus
USB Designer Links - Large collection of USB related links
USB.org - All about the USB standard