PC/104: A legacy of firsts

It is refreshing to take a look back at the development and growth of PC/104 over the last 20 years. From what was initially an open standards concept created and promoted by Rick Lehrbaum at Ampro to today’s rich ecosystem of hundreds vendors with thousands of boards and millions of product in use worldwide, PC/104 has been a great success. This success can be attributed to its small size, PC-compatibility, functionality, scalability, ruggedness, and an actively managed Consortium. Coupled with that is its legacy of product longevity and interoperability due to non-proprietary standards. The result is that PC/104-based products are used in applications for medical, industrial, mil/aero, communications, security, energy, transportation, instrumentation, and much more.

The PC origin

In the 1980s, certain large companies lost sight of the fact that they needed to stick with their core competencies and subsequently had to downsize as they lost money. As a result, many companies began to realize that their area of expertise was not building embedded PCs and that it was better to buy rather than build from scratch due to cost, manpower, and time-to-market considerations. It was at this time that PC/104 technology and products became available, first supporting the ISA bus on the PC/104 connector and later the PCI bus on the PCI-104 connector. With technology becoming more complex, designing single board computers from scratch didn’t make sense for most manufacturers.

Stackable PC/104 embedded PCs were positioned to be a viable solution. PC technology allowed a designer to leverage widely available hardware and the vast software infrastructure supporting personal computers, yet on a small form factor platform whose size and environmental characteristics made them feasible to use beyond the desktop. The popularity of embedded PCs allowed a designer to buy off-the-shelf, fully tested hardware, and further customize it with specialty I/O and application software. PC/104 embraced the emerging PC desktop market and adapted it for industrial applications to about the size of a 3.5" floppy disk.

A record of firsts

PC/104 was the first to recognize the market for small form factor embedded computing modules; size does matter, and smaller is better. With advances in electronics miniaturization over the last two decades, it has been possible to squeeze more and more functionality into less and less space. While the earliest PC/104 modules were one function per board, today an all-in-one SBC with I/O can be realized on just one 3.6" x 3.8" board. Now, defining and placing the I/O connectors on the board has become a real challenge.

PC/104 was the first to promote self-stacking, modular computer elements. Previous solutions, such as Multibus, VME, and STD Bus, required an expensive and bulky card cage. No longer was that needed with multiple PC/104 modules. The PC/104 connectors plus the four mounting holes with spacers made the stack very strong and robust, and expansion and system reconfiguration became easy. Therefore these modules became the electronic building blocks for many different system applications (Figure 1).

Figure 1: PC/104 modules are building blocks for embedded systems.
(Click graphic to zoom by 1.9x)

Long live PC/104

Finally, PC/104 has a long life expectancy. Designers don’t want technology that is here today and gone tomorrow. They need their products to be available for five to ten years and perhaps even longer. If it works, don’t break it.

The PC/104 architecture demonstrated that it is possible to successfully implement quickly evolving PC technology into embedded computing products by taking full advantage of PC market adoption, performance, scalability, and a growing availability of silicon worldwide. Simple and elegant in design, small but rugged in performance, PC/104 technology bridges the successes of the past with the promises of the future as it continues its innovation with PCI Express and beyond.

With the PC/104 Consortium celebrating its 20th year, the stacking architecture of the PC/104 format is as viable and popular as ever. Even as its underlying technology continues to evolve, it’s easy to imagine another 20 years of success for this flexible, off-the-shelf format.

For more information on PC/104 specifications or to search for specific PC/104 products, visit www.PC104.org or search www.smallformfactors.com/products.

PC/104 Consortium 408-337-0904 info@pc104.org