The PC industry is phasing out the ISA (Industry Standard Architecture) bus and there will soon be no consumer level computer motherboards with ISA connectors. Because DFM telescopes use a custom controller card that requires an ISA slot, we thought it wise to purchase a spare system now. A component list follows.
The DFM control system requires a desktop (flat) case. The mounting drawer depth is shorter than some desktop cases so one has to be careful about dimensions. We purchased a Casedge 2100DT ATX case from MNworks, P.O. Box 6201, Mesa, AZ 85216 (480) 818-9197 (480) 986-5350 Mon-Fri 9:00-6:00 PST. Cost was $52.95. Manufacturer's Specifications.
I put a piece of wireloom around the support bar that runs from front to back near the ISA slot to prevent short-to-ground on the controller card.
We replaced the power supply that came with the case with a model T30ATX Turbo-cool 300 ATX from PC Power & Cooling, Inc. (http://www.pcpowerandcooling.com), 5995 Avenida Encinas, Carlsbad, CA 92008, 960-931-5700. Cost was $63.75, ordered on 10/24/02. Manufacturer's Specifications
We believe that a higher quality power supply is less likely to fail during the next few years. Unbranded commodity ATX power supplies may fail to meet their advertised performance specifications (see this article at Tom's Hardware) so using a product supplied by a company specializing in PC power supplies probably increases reliability. Although replacement parts are inexpensive, the nuisance and lost data costs are high so making this switch at the beginning makes sense. We have had good past experience with PC Power and Cooling products.
New telescopes built by DFM use the Gigabyte GA6VTXE motherboard, one of the last equipped with an ISA slot. We purchased a GA6VTXE-A (this one has AC97 audio on-board) from Multiwave/Mwave.com at 17901 E. Ajax Circle, Industry, CA 91748, 626-912-8485. Tech support at 626-912-7641. Cost was $101.23 with a Celeron 900 cpu bundled in. Manufacturer's Specifications.
We installed a VIA C3 650 MHz (100 MHz fsb) processor, replacing the Celeron 900 that came with the motherboard. We chose this processor because of its low heat dissipation requirements, making it likely that a cooling fan failure will not destroy it. Purchased from TigerDirect.com, 175 Ambassador Drive, Naperville, IL 60540, 800-888-6111. Cost $29.99. We note that VIA claims that their 800MHz C3 has the lowest heat dissipation requirement in the processor line. C3 information.
This is a large-finned fan-shaped heatsink that will do an adequate job of cooling the C3 processor. It comes with a large muffin fan that sits above it and would be easy to replace (any PC case fan would work). This solution was appealing because it can be difficult to find a replacement CPU fan on short notice, especially for an outdated CPU. In this case, almost any fan would work and one can be scavenged from old PCs on-site. Product Information.
128MB of memory by Corsair, purchased from Multiwave/Mwave.com at 17901 E. Ajax Circle, Industry, CA 91748, 626-912-8485. Cost was $38.52. The TCS does not require anywhere near this amount of memory (eight times the hard drive capacity) but it's hard to find smaller sets.
Instead of a spinning hard disk, we installed a 16 MB solid state IDE flash memory device. We chose the Acrosser "Disk on Flash" (product information) because it plugs directly into the IDE pins on the motherboard. No software drivers are needed.
We purchased two (one for backup) on 10/24/02 from Circuit Specialists, Inc. (http://www.web-tronics.com), 220 S. Country Club Drive #2, Mesa, AZ 85210, 480-464-2485. Cost was $39 each; Circuit Specialists' model number is DOM-16.
Using a flash disk instead of a spinning hard drive should increase reliability and reduce heat output and power requirements. During normal operations we never write to disk so worries about limited write cycles to a flash disk do not apply. The Acrosser specification is for 1M read/write cycles with data retention of 10 years. Operating temperature range is 0-70 C. As long as the computer and motor driver chassis are powered up, we maintain this temperature range in the computer.
It was inexpensive ($27.00) and available from Mwave, where we ordered many of the other components.
The floppy disk drive was scavenged from an old computer.
December 19, 2002