# Tales from the Chad Box Reading about chad in the newspaper is for me like hearing a Beatles song on the radio --- both stir deep memories of sights, smells, and sounds that were part of my life 30 or 35 years ago. Even as the capacity of computers for audiovisual entertainment has grown, computers themselves have, by and large, lost their physicality. Not a bad thing, as the mechanical parts used to break down the most, but something is gone from the time when you could see a single bit with the naked eye. Chad itself, first of all. I say "chad itself" because in the 1960s "chad" was a collective noun, like "chaff." In fact, though the etymology is obscure, I'll bet the word is related to "chaff," which a fistful of chad resembles, except that the sharp edges of the little cutout pieces make it sensible for the word to end with a dental rather than a fricative. But nobody ever talked about a single chad. Some MIT friends have told me that they called the individual pieces "chits," but I never heard that at Harvard. There is a charming folk etymology: that there was a kind of punch that made U-shaped slits rather than holes, and it had been invented by a Dr. Chadless, so chad was what a Chadless punch did not create. This is, sadly, a better example of geek humor than of word history. No one named Chadless is in the US or UK patent databases, or even in the LDS Church family history records. The punches that did create chad were marvelous machines. I grew up on the PDP-1 and PDP-4 computers in Cruft and William James Hall. They used 1-inch paper tape. The punch created a line of 8 holes across the tape, at a rate of 60 lines per second. So the computer would produce a lot of chad in the course of a day. The chad fell from the punch into the chad box, which you had to empty every now and then. The punch made a high-pitched whining sound that varied somewhat with the pattern of holes punched. If the sound became muffled, you'd forgotten to empty the chad box and the chad was backing up into the punch --- you had to get there before the sound changed to a grind! Paper tape was fan-folded. The paper tape reader pulled it horizontally across a row of sensor lights; the unread and already-read parts of the tape were in fan-folded sections, standing vertically on the folds in bins to the left and right of the sensors. There was a gentle rhythmic sound as the segments unfolded from one bin and refolded in the other: sswhish, sswash, sswish, sswash. Unless, of course, you didn't set the tape in the take-up bin properly at the beginning, or there was more tape than the bin was designed to handle; in that case the rhythmic sound dissolved and the tape quickly formed an ugly mess of loops and squiggles. There were no video terminals; the keyboards were big heavy Teletype machines, adapted from telegraphy, with hundreds of ingeniously interconnected levers and springs inside. During a three-year period I moved up from KSR-28s to ASR-33s to ASR-35s. These had three different kinds of hammering mechanisms; the fanciest had the type in a rectangular array which shifted around in front of a fixed plunger going in and out to make successive imprints. I can still hear the distinctive sound of each of these devices, including the special whirring clunk when a 28 shifted between letters and numbers mode. The Flexowriter was used for preparing punched paper tapes by hand, or printing a punched tape on paper; it had hammers like a mechanical typewriter, one per letter, and went thwapp!, thwapp!, thwapp!, with a big smashing sound when the carriage returned. No one got RSI in those days, and I am not sure why, as many of us worked on these computers every minute we could, all night long if possible. I think it may have been because you just couldn't type very long without having to do something else. You had to load the paper tape reader, empty the chad box, find another box of paper tape and load it in the punch, run over to the Flexowriter and print a listing of the tape that was just punched, get out a single-edged razor blade and splice in a few rows of holes if you wanted to change one instruction in your program, etc. These activities provided breaks and exercised different muscles. All the moving around made it hard to keep track of different parts of the machine; you needed tricks to guess what was going on at the console if you were busy elsewhere. In those pre-miniaturization days, the ordinary operation of the central processor used enough energy to generate some radio frequency radiation. This meant you could put a radio on the console and tune it in between stations; from the other side of the room, the tone of the static indicated whether the machine had crashed or not. We were constantly fussing with individual bits in memory. There were rows of toggle switches which you set up or down to specify binary data, and rows of lights in which the data in memory were displayed. You spent a lot of time setting, reading, and interpreting those patterns; memory was so scarce and programming tools so weak that programmers needed to fiddle with numbers a lot. We worked in octal, taking three bits at a time. To paraphrase the immortal Tom Lehrer, octal is like regular counting, if you're missing two fingers: 1, 2, 3, 4, 5, 6, 7, 10. Setting switches required mental and manual dexterity, and eventually I just thought in octal. During those years I happened to notice when my '63 Dodge was going over 77,777 miles, and I suddenly felt sickened that something was wrong because the odometer didn't roll over to 100,000. Before the integrated circuit, you could look at a core memory plane --- little magnetic donuts strung at the intersections of a grid of thin wires \--- and see where the bits were stored. There were wires, lots of wires, connecting things. And people had to patch wires all the time, replace individual components, and plug things in and out. The manufacturers were always releasing hardware fixes, and any research required some custom hardware fiddling. Of all this I have olfactory memories: the ordinary smell of hot solder, and of burning insulation, during routine repair work or customization; and every now and then, the evil smell of some costly piece of electronics frying inside the running computer --- on one occasion a newly installed 64K memory module that had cost a fortune. If you take a computer apart today, you won't find much inside; it all looks the same. The 1960s were a sort of Cambrian era in the design of devices, with an explosion of experimental forms and materials. I got married straight out of college and went to work as a systems programmer at a national research lab. This was a fool's heaven for an obsessive hacker; if the machine wasn't working, no one could use it till I fixed it, and I got to say whether the machine was working or not. During one marathon stint I was fooling around with some components with liquid mercury inside. When I came home late at night my wife asked me, "How was your day? And just why are you wearing that silver ring rather than your wedding ring, dear?" The mercury had leaked and formed an amalgam with the gold. It was a nice project to figure out how to undo all aspects of this situation. But the boiling point of mercury is less than the melting point of gold, and a friend of mine had a jeweler's oven, so I was able to cook the ring back to its original state. Ring and marriage are both still intact. Except for what one sees on the screen or hears from the speakers, one has little sense of anything actually happening inside a computer today. The integrated circuit changed the world in the 1970s, and the mechanical marvels of the early years have given way to electronic or magnetic substitutes. The abstraction of function from mechanism is a triumph of computer engineering. But as the courts contemplate what's a 0 and what's a 1 on those Florida punch cards, I'm raising a toast to the good old days when bits were something you could see, touch, hear, and sometimes even smell. \- Harry R. Lewis '68, PhD '74, Gordon McKay Professor of Computer Science and Dean of Harvard College