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Building your own computer

Disk Drives

Dead (floppy) duck
Let's get the Floppy Disk out of the way right now. Yes, you must have one, no, they are not exciting. They come in one size (1.44Mb) and colour (beige) and despite the best efforts of various manufacturers to update the humble floppy to something more useful, all attempts to date have failed. Frankly 1.44Mb is so pitifully small they are useless except for booting up a dead PC for diagnostic purposes. The network, and other storage media (eg CDROMs), have far overtaken the humble floppy disk as a (re-)movable storage medium. I predict that manufacturers will eventually drop it, now that you can boot a PC from a CD.

Hard Disk platterNow to Hard disks which are much more exciting. A few years ago, getting 10Mb on a disk was a big deal. Now a 10Gb disk (ie 100 times larger) is considered a bit small. So the rise of the hard disk continues unabated with the most recent hard disks being 200Gb in size. Which is a pity because the method used to communicate with these disks only supports 137Gb; fortunately a new standard has been devised and will be implemented with immediate effect by hard disk manufacturers, motherboard manufacturers and BIOS makers alike. The new standard allows disks so large that you could put all the written works of the entire Earth, of all ages, on it and it would not be even partly full.

So now that we know that the Hard Disk is not dead, and is, in fact, thriving, let's decide what we need for our soon-to-be-built PC. Disks currently come in two speeds: 5,400 rpm and 7,200 rpm. Faster is better. OK, there are some disks out there that spin at 10,000 or even 15,000 rpm but these use a different communications standard (SCSI - pronounced sku'zee), run exceedingly hot, are much more expensive than "standard" disks and are not going to be discussed here. Their usefulness has largely been made obsolete by the ever-increasing speed of standard disks.

We are concerned with IDE (eye-dee-ee) disks, that is, disks that have Integrated Drive Electronics, so the computer does not have to worry about where or how stuff gets to and from the disks it just talks to the electronics on the disk to say, "Hey, give me my data!" and the disk obliges. All non-SCSI disks are IDE so you don't have to worry about anything else.

Does size matter?
Hard Disk unitDisk drives start meaningfully at around 20Gb (Giga-bytes) big, (that's 20 thousand million characters). But 40Gb, 80Gb or larger are becoming increasingly common. Let's pick 40Gb as a useful size. Why so large? Well, the advent of music and video files on the PC has led demand for ever more space. Music files a commonly in MP3 format so each file only takes up about 3Mb. I've got a 40Gb disk with about 8,000 music tracks on it, and I've still space to spare. As I write this page I'm listening to Shakira playing in a jukebox application that continously shuffles my music collection. I would not have been able to do this 5 years ago (1997) - not without spending thousands, anyway.

So we've picked a 40Gb, 7,200rpm IDE disk as a sensible starting point for our PC. Prices drop monthly, so by the time you read this 100Gb or larger will surely be common. This will be ridiculously large even for my music collection, so it will give me room for my video editing too!

Does it come with a starting handle?
Other factors that people used to consider were "seek times", "latency", "buffer size" and probably a few more. These no longer matter with the speed and size of disks available today. After all, do you quiz the car salesman about the compression ratio in your new car's engine? Fifty years they did! Not now though. Times and technology move on at a pace that make such questions meaningless.

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