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1. Motherboard: Jetway NC92-330-LF with the PCMCIA-CF Reader Daughter Board
2. CPU (influenced motherboard choice): Intel Atom 330 dual core 64 bit (only the 230 single core and the 330 are 64 bit).
3. Case: Travla C158 Mini-ITX Case with mounting brackets
4. Sound Card: M-Audio Revolution 7.1 (now discontinued. M-Audio no longer maintains a product page, but here is the manual)
5. WiFi: Uqbiquiti 300mw a/b/g Cardbus wifi card with magnetic roof / trunk mount antenna.
6. Storage: 4GB Compact flash 266x
7. Memory: 1GB low profile DDR2 533
8. Power Supply: Opus 120 watt mobile power supply
9. I-BUS Interface: Serial iBus interface from Rolf Resler

So let’s break it down into what influenced my decisions:

1.  Jetway NC92-330-LF Motherboard: I’ve always been very impressed with Jetway’s offerings, and especially their optional daughterboards that add extra functionality without taking up extra space. The I/O ports for the daughterboards go in the same I/O area as the motherboard. I already had the Ubiquiti card that I had bought back when taking a course in wireless networking. By using the jetway board’s daughter board option for a PC Card I can add wifi to the computer without taking up a pci slot (if a mini-itx has PCI it’s usually just one), or having something external like a USB wireless solution. Most external USB wifi cards, sticks or whatever you call them, have the antenna built in. For the best range and flexibility I wanted to have a choice of antennas, and the Ubiquiti has standard external antenna connectors. The other reason for choosing this board was the Atom processor, which I’ll talk about next.

2. Atom 330 Processor: I chose this for a few reasons. 64 bit. I need 64 bit if I want to do dithering on 24bit audio without taking a huge cpu hit. Why dither 24 bit audio? Because I can! In reality though, by going with the fastest Atom I am giving myself some breathing room to add other applications in the future. Also it is dual core. I am planning on doing both DRC, and active crossover. If I run two instances of BruteFIR tied together with JACK, I should be able to get each core doing some work. Again, more breathing room. Even if I run it all in 1 instance of BruteFIR it handles multiple CPUs. The last reason for the Atom 330 is the power consumption. This guy consumes a whopping 8 Watts! Since the computer will be in the trunk of the car, heat can become a real issue. The less cooling that is needed for the CPU, the less heat is a problem.

3. Travla C158 Case: As soon as I saw the Travla C158 had mounting brackets it was a no-brainer. I had been looking for a case with mounts that would support a single PCI card. Travla was quite smart in how they arranged the case, and the end result is a small case about the size of your average car amplifier. All of the cases currently designed for car / mobile computing don’t support PCI cards and they assume everyone will use the on-board or USB audio. Even if the on-board audio were decent enough in quality, it doesn’t have the I/O I need (2 in, 5 out with upgradability to 7). USB audio would require something outside of the case, which is a situation I wanted to avoid.

4. M-Audio Revolution 7.1 Sound Card: I already mentioned that I wanted to stay inside the case, so a PCI sound card is where I started my search. Soundblaster has been known for quite some time to be pretty bad in the audio community, at least with their older cards that resampled the 44.1kHz audio to 48kHz. M-Audio has long been a professional audio products vendor. I have the philosophy that you get a lot of benefits by buying the low end of professional equipment vs buying the high end of consumer equipment. M-Audio targeted the Revolution series at consumers but has since stopped production. The card operates at 24 bit resolution with a 96 kHz sampling rate, which is much more detail than most consumer cards. It has line level inputs as well as 8 channels out (7.1). I need a lot of channels so I can do active crossovers for each speaker.

5. Ubiquiti Super Range Cardbus Wifi Card: I chose to go with a PC Card as that is my best opportunity to hook up external antennas without occupying a PCI slot. This is also a very powerful card, way too powerful for any antennas I currently have, so I have to keep the power scaled back. The card can output at 300 mW (milliwatts). The Linksys WRT54GS, a very popular home router / access point comes by default set to 28 mW. Also this card uses the Atheros chipset, which is very well supported on Linux.

6. 4GB Compact Flash: Compact flash has long been a favorite choice for embedded solutions. One design of CF that has played out well is that the controller for addressing the flash is on the card itself. This has allowed the cards to keep getting bigger and bigger and still work with older devices. In the digital camera world this is a main reason for them remaining very popular even though they are much larger in size than say a Micro-SD card. CF cards are seen just like IDE / ATA devices to the OS, and the pins are pretty much just mapped to the appropriate pins on an IDE / CF adapter, making the adapter cheap. In my case, I don’t need a lot of storage for the OS, but I wanted a fast card. The 4GB card I purchased was about the cheapest 266x card at the time, ~ $15. Also, this system is designed to run with no swap, so read speeds are really all I’m concerned with.

7. 1GB DDR2: Not much deciding here, other than looking at price and height of the stick. The Travla case needs low-profile memory (it takes 1 stick) if you ever want to add in a CD/DVD drive.  512MB and 1GB were almost the same in price so I went with 1GB. However I should not need nearly that much even though I have no swap.

8. Opus 120 Watt Mobile Power Supply: Mobile power supplies are a must when running a PC in the car. The features in the Opus that I liked are:

• Wide range of input voltage: Depending on other accessories, driving speed etc the voltage seen by the power supply can range from about 11.8 volts to 13 volts in my car.
• Configurable shutdown delay: This allows me to get gas, run into 7/11 etc without the computer shutting off.
• Configurable delay for turning on audio amplifiers: I hook the remote wire from my stereo to the Opus, which let’s it know to turn on / off. It then supplies its own remote output which turns on the amps. By putting a delay on the remote output the computer can boot past the point of the typical audio thump before turning on the amps. That thump can be very damaging to speakers, especially when running amps that are turned up so that the volume is controlled externally.
• 120 Watts is plenty of headroom for adding a hard drive and CD/DVD drive later.

9. IBus Interface: There really aren’t many choices here. I did choose to use the the serial version instead of USB. The USB version just complicates things. For example, would it come up as the same device ID every boot if you had multiple USB devices? Not unless you do some extra work. Serial is much more common in embedded environments.