GUI Bytes

Twenty Years Ago, Part 3 - Disk Storage

part 2 - RAM

In the last column we looked at random access memory (RAM), the kind of memory your computer uses when it thinks. Memory of this type is known as volatile memory, as it lasts only as long as the computer is turned on. Once you shut it down, everything in RAM disappears. While this is no problem for "thinking" memory, we also expect the computer to remember things from one day to the next; if we had to re-enter data every day, the usefulness of the computer would be much reduced.

As noted in the last column, the QX-10 had 256K of RAM, but it also had two 5-1/4 inch floppy drives. At that time there was no permanent memory other than removable disks, so each time the computer was turned on you had to insert one or more floppy disks to load the operating system and the program you wanted to use. Not until you were done with that could you load data to work on, from yet another disk.

A year or so after I bought my QX-10 I was tempted to buy a hard drive so I wouldn't have to feed a series of disks in every time I wanted to use the computer. Unfortunately, the cost was prohibitive - about $2,000 for a 10 meg drive - and I resigned myself to a tedious boot process.

Fortunately, disk drives quickly evolved. Each new floppy disk format was physically smaller, yet held more information than its predecessor. I still have an 8-inch floppy, which held just over 100K. My QX-10's 5-1/4 inch drives, which held about 340K, were replaced with the still-popular 3-1/2 inch drives with 1.44 megabyte capacity. There was a brief flirtation with 2-inch drives, but they didn't see much use, probably because they were too small to contain even the briefest description of their contents!

During the same time, hard drives have increased in capacity from 10 megabytes to 200 or more gigabytes (one gigabyte = one billion bytes), while the price has fallen dramatically. The cost of hard drive storage for my computer in 1984 was about $200 per megabyte; today it is only about 10 megabytes per cent!

I recently bought a pair of Lexar JumpDrives, portable storage devices about as big as your thumb that plug directly into the computer's USB (universal serial bus) port. The ones I bought hold 128 megabytes each, but they are now available with up to one gigabyte capacity.

 

The picture shows an 8-inch floppy, a 3-1/2 inch floppy, and a Lexar JumpDrive. Quite a change - from a disk nearly as big as a notebook that would hold 100K, to something small enough to hang on your keychain that will store ten thousand times as much as the big disk.

Staying with removable disks, we now have DVD disks. The size is a bit of a step backward, at about 4-3/4 inches diameter, but the capacity is amazing. A 2-side, 2-layer DVD disk holds about 17 gigabytes, 170,000 times as much as an 8-inch floppy!

That's a lot of information, but what does it mean? The lowest level DVD, storing information in a single layer on one side, holds just over two hours of high-quality video, with multi-channel Dolby sound. Anyone who has rented a DVD knows that a single disk often contains not only the movie - sometimes in a choice of format - but a choice of language, subtitles, and commentary, along with trailers, outtakes, interviews, and more.

2003 Sheldon Wolfe, RA, CSI, CCS, CCCA, swolfe@bwbr.com 
on the web at www.CSI-MSP.org 


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