Here are some links to information about the MicroChannel Architecture (MCA) bus, as used in many IBM PS/2, RS/6000, AS/400, and 370 machines.

From Christophe Beauregard.

IBM Microchannel Enthusiasts Page including his famous QBMCA Microchannel Adapter Identification Software and hundreds of ADFs for IBM MCA-machines.

The effects of M.A.D. Microchannel Addictive Disorder.

Information about IBM PS/2 machines. Although mainly directed at the MicroChannel systems (model 50 and above) there may be the occasional snippet about the lower end ISA-based systems as well.

Micro Channel Bus technical summary.

IBM's answer to the failings of its older PC bus, which is now referred to as the ISA bus, article discusses the problems and short falls it had.