We had a human/computer interface a hundred years before we had computers. When computers came into being around the time of the Second World War, humans, quite naturally, communicated with them by simply grafting them on to the already-existing technologies for translating letters into bits and vice versa: teletypes and punch card machines.

These embodied two fundamentally different approaches to computing. When you were using cards, you'd punch a whole stack of them and run them through the reader all at once, which was called batch processing. You could also do batch processing with a teletype, as I have already described, by using the paper tape reader, and we were certainly encouraged to use this approach when I was in high school. But--though efforts were made to keep us unaware of this--the teletype could do something that the card reader could not. On the teletype, once the modem link was established, you could just type in a line and hit the return key. The teletype would send that line to the computer, which might or might not respond with some lines of its own, which the teletype would hammer out--producing, over time, a transcript of your exchange with the machine. This way of doing it did not even have a name at the time, but when, much later, an alternative became available, it was retroactively dubbed the Command Line Interface.

When I moved on to college, I did my computing in large, stifling rooms where scores of students would sit in front of slightly updated versions of the same machines and write computer programs: these used dot-matrix printing mechanisms, but were (from the computer's point of view) identical to the old teletypes. By that point, computers were better at time-sharing--that is, mainframes were still mainframes, but they were better at communicating with a large number of terminals at once. Consequently, it was no longer necessary to use batch processing. Card readers were shoved out into hallways and boiler rooms, and batch processing became a nerds-only kind of thing, and consequently took on a certain eldritch flavor among those of us who even knew it existed. We were all off the Batch, and on the Command Line, interface now--my very first shift in operating system paradigms, if only I'd known it.

A huge stack of accordion-fold paper sat on the floor underneath each one of these glorified teletypes, and miles of paper shuddered through their platens. Almost all of this paper was thrown away or recycled without ever having been touched by ink--an ecological atrocity so glaring that those machines soon replaced by video terminals--so-called "glass teletypes"--which were quieter and didn't waste paper. Again, though, from the computer's point of view these were indistinguishable from World War II-era teletype machines. In effect we still used Victorian technology to communicate with computers until about 1984, when the Macintosh was introduced with its Graphical User Interface. Even after that, the Command Line continued to exist as an underlying stratum--a sort of brainstem reflex--of many modern computer systems all through the heyday of Graphical User Interfaces, or GUIs as I will call them from now on.

Now the first job that any coder needs to do when writing a new piece of software is to figure out how to take the information that is being worked with (in a graphics program, an image; in a spreadsheet, a grid of numbers) and turn it into a linear string of bytes. These strings of bytes are commonly called files or (somewhat more hiply) streams. They are to telegrams what modern humans are to Cro-Magnon man, which is to say the same thing under a different name. All that you see on your computer screen--your Tomb Raider, your digitized voice mail messages, faxes, and word processing documents written in thirty-seven different typefaces--is still, from the computer's point of view, just like telegrams, except much longer, and demanding of more arithmetic.

The quickest way to get a taste of this is to fire up your web browser, visit a site, and then select the View/Document Source menu item. You will get a bunch of computer code that looks something like this:

This crud is called HTML (HyperText Markup Language) and it is basically a very simple programming language instructing your web browser how to draw a page on a screen. Anyone can learn HTML and many people do. The important thing is that no matter what splendid multimedia web pages they might represent, HTML files are just telegrams.

When Ronald Reagan was a radio announcer, he used to call baseball games by reading the terse descriptions that trickled in over the telegraph wire and were printed out on a paper tape. He would sit there, all by himself in a padded room with a microphone, and the paper tape would eke out of the machine and crawl over the palm of his hand printed with cryptic abbreviations. If the count went to three and two, Reagan would describe the scene as he saw it in his mind's eye: "The brawny left-hander steps out of the batter's box to wipe the sweat from his brow. The umpire steps forward to sweep the dirt from home plate." and so on. When the cryptogram on the paper tape announced a base hit, he would whack the edge of the table with a pencil, creating a little sound effect, and describe the arc of the ball as if he could actually see it. His listeners, many of whom presumably thought that Reagan was actually at the ballpark watching the game, would reconstruct the scene in their minds according to his descriptions.

This is exactly how the World Wide Web works: the HTML files are the pithy description on the paper tape, and your Web browser is Ronald Reagan. The same is true of Graphical User Interfaces in general.

So an OS is a stack of metaphors and abstractions that stands between you and the telegrams, and embodying various tricks the programmer used to convert the information you're working with--be it images, e-mail messages, movies, or word processing documents--into the necklaces of bytes that are the only things computers know how to work with. When we used actual telegraph equipment (teletypes) or their higher-tech substitutes ("glass teletypes," or the MS-DOS command line) to work with our computers, we were very close to the bottom of that stack. When we use most modern operating systems, though, our interaction with the machine is heavily mediated. Everything we do is interpreted and translated time and again as it works its way down through all of the metaphors and abstractions.

The Macintosh OS was a revolution in both the good and bad senses of that word. Obviously it was true that command line interfaces were not for everyone, and that it would be a good thing to make computers more accessible to a less technical audience--if not for altruistic reasons, then because those sorts of people constituted an incomparably vaster market. It was clear the the Mac's engineers saw a whole new country stretching out before them; you could almost hear them muttering, "Wow! We don't have to be bound by files as linear streams of bytes anymore, vive la revolution, let's see how far we can take this!" No command line interface was available on the Macintosh; you talked to it with the mouse, or not at all. This was a statement of sorts, a credential of revolutionary purity. It seemed that the designers of the Mac intended to sweep Command Line Interfaces into the dustbin of history.

My own personal love affair with the Macintosh began in the spring of 1984 in a computer store in Cedar Rapids, Iowa, when a friend of mine--coincidentally, the son of the MGB owner--showed me a Macintosh running MacPaint, the revolutionary drawing program. It ended in July of 1995 when I tried to save a big important file on my Macintosh Powerbook and instead instead of doing so, it annihilated the data so thoroughly that two different disk crash utility programs were unable to find any trace that it had ever existed. During the intervening ten years, I had a passion for the MacOS that seemed righteous and reasonable at the time but in retrospect strikes me as being exactly the same sort of goofy infatuation that my friend's dad had with his car.