I can usually one-up most anybody when it comes to my first computer (anybody except my mom, that is…more on that later). Around 1981 or 1982, I got a Sinclair ZX81, probably for Christmas or my 11th or 12th birthday. My dad says that ‘we’ assembled it from a kit, which undoubtedly means he assembled it from a kit and I watched as long as my 11-year-old attention span allowed.
The ZX81 rocked a Zilog Z80 8-bit CPU at 3.25 MHz. For those of you who grew up in the 90’s and never saw an ‘M’ in front of the ‘Hz’, that’s three and a quarter megahertz, just about 1⁄1000 the speed of today’s PCs (if a cycle got the same amount of work done, which it certainly didn’t). The operating system was BASIC, and programming was accomplished using the pressure-sensitive membrane keyboard (sort of like the pin pad of an ATM or gas pump). The keyboard was only about six inches wide, so typing was strictly a hunt-and-peck affair; even my 11-year-old fingers wouldn’t fit on ASDF JKL;.
I remember people not really knowing what to make of it. What is that? A computer. Looks like a calculator. No, just a small computer. So, like a calculator? Nope, it’s a full-blown computer. Looks like a calculator to me; are you sure it’s not a calculator?
I think my interlocutors usually left with the idea that I just didn’t know the difference between a computer and a calculator.
It had one kilobyte of onboard RAM memory. Again for the 90’s kids, that’s about 1⁄8,000,000 of what a cheap laptop ships with today (1 kB = 1⁄1000 MB = 1⁄1,000,000 GB). But not to worry, I had the optional 16 kB RAM pack (that clunky thing stuck to the back in the above picture). The RAM pack immensely increased what you could do with the ZX81, but it was notorious for losing its connection and crashing the computer. From Wikipedia:
The RAM pack was top-heavy and was supported only by the edge connector. It had a habit of falling out of its socket at crucial points and crashing the ZX81, losing anything that the user had typed in. Users turned to using sticky lumps of chewing gum, double-sided tape or Blu-Tack to cure what became known as the “RAM pack wobble” problem.
Much wailing and gnashing of teeth accompanied those crashes, especially when I had painstakingly hunted and pecked in a couple of hundred lines of BASIC code.
What about storage? I had never heard of a hard drive in those days. No, the ZX81 used an off-the-shelf cassette recorder for storage. I believe mine was from Radio Shack, but the one in the picture below is a reasonable facsimile. You could listen to your programs, if you were so inclined, by playing them back on the cassette recorder’s speaker. I recall them sounding a lot like a dial-up modem carrier tone, but it was a long time ago, so I’m not sure.
So, yeah, I can (and do) one-up all you fancy folks with your C64’s, your Apple IIe’s, and your TRaSh-80’s (if your first computer had a hard drive, you’re not in the running). Started thinking myself bad, until I tried to pull that shit with my mom. My mom, you see, worked for the Air Force in the mid to late 60’s. That’s her on the right, in the picture below.
The ZX81 would have seemed like an alien artifact in 1966, and the tape drive I thought was so primitive? My mom used punch cards.
She worked in Procurement, and Procurement at Patrick Air Force Base used the FLAC system:
FLAC’s basic electronic element was the vacuum tube, but it also used crystal diodes for gating. The complete system comprised 1,050 vacuum tubes of 5 different types and 18,000 crystal diodes, but the computer proper used only 420 6AN5 tubes and 15,000 diodes.
The system clock ran at 1 MHz. Addition operations took, on average, 850 microseconds, whereas multiplications and divisions took 3300 microseconds.
3.5 MHz doesn’t seem so bad, now. And I had BASIC:
All programming for FLAC was written in machine language, as the machine lacked any high-level language, assembler or compiler.
Remember me complaining about the keyboard? FLAC used the Friden Flexowriter for input, something like this:
FLAC also weighed half a ton, took up a medium-sized closet, consumed 7500 Watts, and cost half a million dollars. The ZX81, 15 years later, weighed 12 ounces, was 6.6 inches wide, consumed about 4 Watts, and cost £49.95 for the kit.
For reasons I don’t remember, my ZX81 was replaced in 1983 by a Timex-Sinclair 1000. I know this because my uncle has a VHS video of my 13th birthday (unfortunately never digitized…if you’re reading this, Uncle Ray, I would love to have a copy). I saw the video a few years ago, and I remember my mop-headed, 13-year-old self exclaiming, “Dad, this one’s got 2k of RAM!”