标签: LGP-30

At this moment, you have most likely heard that Embedded Systems Design magazine had its last print issue. That occasion is especially poignant for me, because so much—20+ years—of my career has been tangled up with the magazine in general, and the Programmer's Toolbox column in particular. Some folks have been blessed (or cursed) by careers that are "linear." They start one job, stay with it, move up the ladder, and retire happy. Mine hasn't been that way. It's taken some sometimes-unexpected twists and turns—some more pleasant than others. Not all of those directions have had anything whatever to do with embedded systems. I thought, however, that you might enjoy hearing about the ones that did. But first, I need to set the stage with a little background. Giant brains I've been involved with computers for a long time. How long? Here's a hint: The textbook for my first computer science class, in 1956, was entitled Giant Brains, or Machines That Think . Back then, the notion of "micro brains" wasn't even a blip on anyone's radar. Computers were—and, we assumed, always would be—monster, power-hungry machines that filled large rooms with glass walls, raised floors, and over-engineered cooling systems. The computer room of 1960 felt more like a cathedral than a place of science, and it had its share of mysterious icons, rituals, a small army of acolytes, and a hierarchy of priesthood, from floor supervisors to managers to that highest of all high priests, the systems administrator. This was my world for the next decade or so. Not that I actually got to enter the computer room, of course. That privilege was reserved for the anointed. We mere engineers and scientists were not welcome. Heck, it was two years before I even saw the computer, and that was from the outside of those glass walls, looking in. My only contacts with it were the "keypunch girls" who punched my card decks, and the clerk behind the counter who accepted my jobs and returned their results. If, on rare occasions, I interacted with the priesthood, it was in hushed and reverent tones, and a proper air of respect. I resisted the urge to genuflect. Now, when you consider that the purpose of the computer was, after all, to help us scientists and engineers solve our problems, it may seem hard to understand why we customers were treated so shabbily. The explanation has to do with money and bureaucracy. In those days, computer time was expensive: $600 per hour. That's in 1960 dollars, when a Coke cost a nickel, gasoline 25 cents per gallon, and that $600 would pay my salary for six weeks. So the priesthood tended to guard the computer jealously. To them, we were not so much valued customers, as necessary evils to be tolerated, however grudgingly. The systems administrator was not judged on how many problems that were solved, but by his ability to keep the computer backlog down. Backlog, as in the number of jobs waiting in the queue. The easiest way to keep the backlog down was simply to deny access to the job queue, or to abort jobs on the flimsiest of excuses. In one shop, I had jobs rejected because the card deck had too many rubber bands around it. Other times, too few. One computer group actually issued written guidelines for how many rubber bands should be used, per inch. The only problem was that the computer operators didn't follow their own guidelines. So a deck they returned to me was likely to be rejected on the next turnaround. Despite the oppressive, Big Brother environment, we got exciting things done. We did, after all, help Neil and Buzz walk on the Moon. What's more, it was in this environment that I learned my craft and developed techniques that I still use today. I did, however, take one thing away from the experience: A deep and abiding hatred of systems administrators. First personal computers During those oppressive years, I found a glimmer of hope and a glimpse into the future. I discovered that not all computers had to be large, nor limited in access. Around 1961, I gained access to what we'd now call a personal computer. The Royal McBee LGP-30 was about the size of a desk. 3 A vacuum-tube machine, it had a grand total of 15 flip-flops. Its only memory was a 4k, magnetic drum. All the data—even the machine registers—resided there. Bits marched to/from the drum in serial fashion. "Bulk storage" was rolls of paper tape. As primitive as the LGP-30 was, it offered important advantages over the Giant Brains. First, I didn't have to beg for permission to use it, No accountant or systems administrator stood behind me, tapping his foot. And though the computer was shared among our team, I had virtually unlimited access to it. Saving computer clock cycles was no longer an issue. Most importantly, I could use the LGP-30 interactively. I'd sit down at its console, a modified electric typewriter, and type. Answers came back in seconds, on the same page. I didn't have to learn and use machine language; the LGP-30 sported a primitive interpreter. If you think of it as a 1960 version of an Apple, with paper tape instead of tape cassettes, you won't be far from wrong. Using that computer, I formulated a philosophy that I've held ever since: Having virtually unlimited and interactive access to a small computer is infinitely preferable over needing an act of Congress and wading through a hierarchy of bureaucrats, to get batch-mode access to a big one. Limited though a small computer might be, a "turnaround" time in seconds trumps one in hours or days. I got a lot of problems solved with that old computer, but my main take-away was a dream. Someday, I vowed, I'd have a computer of my very own. I wouldn't have to justify my use of it to anyone. Its only job would be to sit on my desk, waiting for me to give it something to do. And if I chose to use it frivolously, inefficiently, or not at all—well, that would be entirely up to me.