We needed to cram all the hardware in an extremely small case, only 7 inches wide, 10 inches deep and 2 inches high. Due to the very limited space available, all the connections had to be made inside the case itself, rather than being external ports like you have on a normal PC. Figure 2 shows the assembled CPU mounted in the car's trunk area and Figure 3 shows the same shot with the access panel in place.

Figure 2: The case installed in the vehicle

Figure 3: CPU covered with access panel

The VIA EPIA MII10000 motherboard fit the bill for us: it's very small, at only around 6.7" square, and has the one PCMCIA slot we require. Indeed, at the time of assembly it was the only motherboard of this size that had a PCMCIA slot!

The M1-ATX was the ideal choice for the power supply, as it provides 90 W of power, and also has an integrated startup/shutdown controller. It was also the lowest cost PSU for what we needed, and had another feature that was well suited to a CarPC: voltage monitoring. Since the computer will always be on in standby mode (for fast start-ups) the computer will always be slightly draining the car's battery. (You can purchase the M1-ATX from mp3Car.com, eBay or just Google/Froogle "M1-ATX" for a list of other vendors.)