Bally Manufacturing Corporation (1980), US Patent No. 4,198,051: www.uspto.gov

Boondog Automation (1998), 8255 IBM PPI PC Interface Card: www.boondog.com/tutorials/8255/8255.htm

Bork, John R. (2005), Reverse Engineering a Microcomputer-based Control Unit: www.ohiolink.edu/etd/view.cgi?bgsu1120167127

Jameco Electronics: www.jameco.com

Pinball Machine Reverse-Engineering Kit: sourceforge.net

Saikkonen, Riku (2000), Linux I/O port Programming mini-HOWTO: www.tldp.org/HOWTO/IO-Port-Programming.html

Salzman, Peter Jay (2004), The Linux Kernel Module Programming Guide: www.tdlp.org/LDP/lkmpg/2.6/html/index.html