PC/104 is an embedded computer standard which defines both a form factor and computer bus. The PC/104 form factor was originally devised by Ampro Computers in 1987, and later standardized by the PC/104 Consortium in 1992. By standardizing the hardware, embedded system designers can substantially reduce development costs, risks, and time. This means faster time-to-market and the ability to hit critical market windows with timely product introductions.

Choices, Choices
The two most common form factors defined by this standard include the PC/104 and the PCI-104. The PCI-104 form factor includes the PCI connector, but not the ISA connector, in order to increase the available board real estate. Based upon market research provided by VDC, 25% of the market currently uses PC/104, while 40% uses PCI-104. Each form factor will keep the same ratio share until at least 2010.

PC/104 vs. PCI-104
While similar, these two form factors are actually competing with each other. PCI-104 is considered the next generation of PC/104, and though the PCI-104 has a much higher throughput, many users do not feel an urgent need to upgrade. If their systems are meeting the need for their applications, after all, there may be no need.

One limitation of PCI-104 of course is that it only permits four PCI cards along a bus segment without a bridge. In contrast, the ISA-based PC/104 has no specific limit to slot count, although typically no more than six cards are stacked together. However, the common ideology is that the march of technology is inevitable, and PCI-104 is believed to be the future trend.