My First Computer – Scull-Tek CP/M

Beginning today, BVC begins a weekly series in which members wax nostalgic about their first computers. You never forget your first, right? Look for a new “My First Computer” post every Friday.

My First Computer
by David D. Levine

I got into the computer game early, because my father was a professor of Computer Science. From the time I was eight or ten years old, we had a chattering Teletype (all caps, yellow roll paper) in the basement, connected by a dedicated phone line to the timeshared computer at the university. Using that terminal and the fancy Diablo daisywheel printer in the CS lab, I turned in the first student paper my seventh-grade teacher had ever seen that had no typos.

Then, when I was getting ready to go off to my sophomore year at college, 1981, my dad decided that I should have a computer of my own. This was not completely unheard-of at the time; some of my college friends, most of whom were CS majors, had Apple II or TRS-80 computers. But my dad and I had bigger plans.

We would build our own.

Dad teamed up with some friends and did a bulk buy of a dozen Scull-Tek “single-board computer” circuit boards, a dozen eight-bit Z80 microprocessors, and enough RAM to fully populate each one with the maximum 64kb of memory, as well as all the necessary power supplies, disk drives, cables, and other folderol to turn these circuit boards into complete, working computers. One of them was destined to be mine.

64kb of memory. Think about that. That was a lot of memory at the time — the Apple II maxed out at 48kb — but by today’s standards… well, the cheapest Mac Mini you can buy today has 4GB of RAM, which is sixty-five thousand times as much.

Dad and I and his techie friends (grad students, most of them) got together with this big pile of electronic stuff and began soldering components onto circuit boards, plugging cables into sockets, and bolting gizmos into boxes. It took a few weeks before the first one came to life, and even though the only thing you could do with it was type a few very basic BIOS (Basic Input/Output Subroutine) commands through an attached terminal, it was still pretty exciting to see something I’d built with my own hands actually reading and responding to commands.

Scull-Tek 1 (1981)I mentioned a “terminal.” This was a specialized device, separate from the computer itself, that combined an alphanumeric display with a keyboard. There was essentially no such thing as a graphical user interface in those days. Pretty pictures were for specialized, expensive CAD (Computer-Aided Design) workstations — home computers used good old letters and numbers, displayed in a rigid grid 80 characters across and 24 characters high. Much of the time you would use the CP/M command line (CP/M, Command Program for Microprocessors, was the computer’s operating system… it was the primitive forebear of DOS, if you can imagine such a thing) but some fancy programs, such as WordStar, would use the entire screen for word processing or spreadsheets. There was no mouse or trackpad; you would move the cursor around with arrow keys, or if your terminal lacked arrow keys (as many did) you would use the classic “cursor diamond” of Control-S, Control-D, Control-E, and Control-X for left, right, up, and down respectively.

My first terminal was an ADM-3, the Volkswagen of terminals, which you can see in the photo above. This terminal was so primitive that lowercase letters were an extra-cost option, I kid you not. The computer itself is the blue-and-white box to the right of the terminal, with the “near letter-quality” Epson dot-matrix printer sitting on top of it. At the time, there was considerable argument over whether the output of a computer printer was good enough to submit to a professor or a publisher; high-quality laser and inkjet printers were many years in the future.

8-inch-floppyThe two dark toaster-like slots on the front of the computer are eight-inch floppy disk drives. An eight-inch floppy looks like some kind of comical clown thing today. Many people over thirty can remember using 5¼” floppies; 8″ floppies were almost identical in appearance, but almost twice as big. But despite their laughable size, they were tiny in capacity: each disk could hold a maximum of 237kb. Or, to put it another way, 1/25th of the MP3 of Carbon Leaf’s “Life Less Ordinary” (5.8MB).

But audio files were not even a pipe dream at that point. Most computer files were either programs — often hand-coded in assembly language to save space and run faster — or plain text, perhaps with a few control characters sprinkled in to specify bold and underline. Yes, underline, not italics; that terminal and “near-letter quality” printer couldn’t cope with anything much fancier than a plain typed page. Basically, the only fonts in the entire world were Courier 12 and Courier Bold 12, and the bold was faked by overprinting the same character three or four times. So the data files were small; you could pack 600 single-spaced pages of typed text onto that 237kb floppy.

But, of course, this computer had no hard disk. As far as long-term storage, the floppy drive was it. So you had to leave room on the floppy for the software… which is why the computer had two floppy drives. Generally one of the drives would hold the CP/M operating system and one or two programs (usually WordStar, in my case) and the other the data files. If you wanted to use a different program, you had to reboot the computer with a different floppy in the A: drive. And because WordStar was a sensible program and always kept a backup, and furthermore didn’t like to delete an old backup until the new backup had been successfully created, the effective capacity of the data floppy was reduced to just 200 pages of text. If you were working on a document that was much bigger than that, and the disk filled up… bzzt! You blew it, Charlie, and all your work could vanish completely. Try writing a novel (a typical novel is about 250 single-spaced pages) or a graduate thesis under those circumstances.

Scull-Tek 3 (1983)But what is a computer without networking? Even in those primitive days we could connect with the Net… not the Internet, yet, but there were dial-up bulletin board systems run by computer hobbyists, and large multiuser systems like CompuServe and The Source (though not yet AOL nor GEnie; even those were a few years away). This picture was taken in 1938 1983 (by which time I’d obtained a more advanced terminal with a detachable keyboard), and to the right of the terminal you can see the “acoustic coupler,” a box with two rubber cups into which you would stick a telephone handset (remember them?) to achieve a communication speed of, if you were lucky, up to 300 baud. “Baud” is roughly equivalent to bits per second, and there are eight bits in a byte, which means that to download that MP3 of “Life Less Ordinary” at that speed would take… about 45 hours. For one song. If the connection stayed up, and there wasn’t a lot of noise on the line.

The iPod Nano in the watch pocket of my jeans right now has between ten and two hundred times as much computing power as that system, depending on how you measure it, and twenty thousand times as much storage capacity… not to mention a high-density color touch screen that, back then, was absolutely something from the realm of science fiction. And yet that amateurish, hand-soldered computer got me through college and my first year in the working world.

And my fingers still remember the WordStar control codes.



My First Computer – Scull-Tek CP/M — 3 Comments

  1. 1938!! Oh my. My first home computer was the IBM PC1 from 1981 with the enormous 64K RAM (that was optional) and 2 floppy drives. I later added the 8087 chip for floating point calculations and could run Lotus 1-2-3.

  2. Typo corrected, thanks for the heads-up. Though, I dunno, sometimes it feels like early computers were that long ago even though I wasn’t born till 1948. My current phone, an elderly-for-smartphones Droid X, has more memory, storage, speed, power, and connectivity than all the computers I’ve owned up till the current one, *combined.* Which is pretty amazing.

    • When I started work as a programmer at the Home Office in 1977, our computer – which lived in it’s own pressurized room – had 48k words of memory (a word = 24 bits). It’s main storage was a drum – plus mag tape. and input was by card or paper tape.