The VMEbus dates back to the early 80's, but widespread use continues today. VMEbus boards are based on the Eurocard format and plug into a backplane. The VMEbus has outlasted other competing architectures, such as the Intel-backed Multibus, and has continued to evolve with new technologies like VME64, hot-swap capabilities, and various mezzanine interfaces such as IP Module, XMC, and PCI Express. The VMEbus is also known as the ANSI/IEEE 1014-1987 specification.
The VMEbus is used extensively in industrial applications such as telecommunications, digital signal processing, data acquisition, factory automation, process control, and also in mil-spec applications. Many VME boards are available, from the common Single Board Computers, to graphics boards, analog interface boards, signal processing, and general-purpose module carriers.
CompactPCI is a later-generation Eurocard-based architecture. In CompactPCI, the passive backplane carries PCI signals to interconnect the boards. The original CompactPCI has been enhanced with several high-performance specifications developed by PICMG, the trade association of CompactPCI manufacturers.
The PC/104 computer bus differs from other architectures in that it has no backplane but instead the boards interface by stacking them on top of each other. The form factor was first introduced by Ampro computers. The signals in a PC/104 or PC104 are the same as the ISA (PC) signals. Usually, the bottom board is a PC-compatible motherboard to which special function boards are stacked. There are several form factors associated with PC/104, such as PCI/104-Express, EBX, and EPIC.
PC/104 systems, due to their small size are most often used in embedded applications.