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The August meeting of the Orangevale chapter was a continuation of our July meeting, which was dedicated to hardware repair and upgrade. Axel Larson had agreed to prepare a presentation for the members on SCSI. This choice grew out of a discussion of hard drives and the relative merits of IDE vs. SCSI, during which it became obvious that while many of us were familiar with IDE, most of us had only a passing familiarity with the SCSI alternative.
Our July meeting was designed as an extended question and answer session for purchasing and upgrading computers. Using the premise that a Pentium 133 needed upgrading, a number of the more technically inclined members joined in a roundtable discussion and shared thoughts and ideas concerning what to buy, where to buy it, and how to build it. The topics included such esoterica as brands of motherboards, ATX vs. AT form factors, power supply connectors, bus speeds, and the past, present and future of random access memory (RAM). Along the way, we touched on video and sound cards and took a brief look at some other peripherals before we ended the session discussing hard disk drives. After a quick review of spindle speeds, capacities, and UDMA vs. SCSI, we concluded that we needed a lot more information. So, before leaving the topic, Axel Larson agreed to teach a session on SCSI for us at the August meeting.
Axel put together a great presentation using PowerPoint together with some neat props. The props were dismantled hard drives of different eras which illustrated the mechanics of the drive. These were used to illustrate the seek, search and transfer functions. He also used them to show that, in effect, all hard disk drives SCSI, IDE, etc., are essentially the same mechanically, differing in their controllers and translation mechanisms. IDE is a dumb device with a dumb controller. Its logic is contained in the software driver and consequently it puts a heavier load on the CPU. SCSI has its own onboard processor so that the logic is in the firmware and is less dependent upon the CPU.
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Axel's presentation led us through a comparison of SCSI vs. IDE describing the advantages, drawbacks and features of each. IDE is cheaper and simpler and, as it becomes more sophisticated, it is gaining a little on SCSI's historical speed advantage. IDE, however, is synchronous (slower) and can provide only a limited number of devices per machine. It consumes one IRQ for two devices and has only two controllers per system. SCSI is faster and can connect from 6 to 44 devices using one IRQ. It can be either internal or external where IDE is limited to internal devices, and it's fairly simple.
No review of SCSI is complete without looking at the myriad of connectors and cabling variations used in SCSI applications. There are a number of very successful business across the county dedicated solely to producing SCSI cables. SCSI also has multiple standards which can be confusing and costly and these are drawbacks which offset somewhat the speed and efficiency advantages.
Axel's presentation is a concise synopsis of the IDE vs. SCSI and we're going to ask him to upload it to our Web site. It's worth taking a look at if you're thinking of moving into SCSI or if you just have a curious mind; for most of us whose interest is limited to home use, the cost/benefit is probably not worth it. But for critical business applications, for network servers, or for any place speed and efficiency are critical, SCSI continues to be the drive and bus of choice.
The Orangevale/Folsom Chapter meets on the fourth Thursday of each month at the Church of Religious Science in Orangevale, 6035 Main Avenue, between Greenback Lane and Madison Avenue, from 7 PM until 9 PM.. Our next meeting will be September 23 and will feature officer nominations and more on Office 2000. For additional information log onto our Web site. Everyone's welcome to join us. See you there!
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Mike Evans
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