This pages describes technologies used in industrial PCs and special PCs made for special applications. It is PC hardware which looks like quite different from the typical PC on your desk or your laptop computer, but is very similar to normal office PC on software viewpoint.
CompactPCI is a special industrial version of PCI bus. It support up to 8 cards in single backplane bus (and more card with bridge chips) and hot-swapping. CompactPCI systems are typically build to mechanically very stable 19" rack enclosures.
PC/104 is an embedded PC hardware system where the whole computer system is built by stacking postcard size PC motherboard and interface cards on top of each other. Original PC/104 standard supports ISA bus architechture for the cards. Newer PC/104+ standard has added PCI bus support for newer PC/104+ systems.
PMC is short for PCI Mezzanine Card. It is a postcard size small module which can be plugged to industrial PC motherboard PMC interface connector or to external carrier card. PMC card carry PCI bus signals in tiny connectors.