The physicality of computing

Intuitions are very important; they are the foundations of our thinking. But explaining or even merely “grasping” our intuitions is difficult. This is a story about my intuitions about computing. Lightly edited from a recent email:

My programming skills are minimal; and I’ve never done more the small example programs and that was long ago. These days I hand-code my posts, but that’s not programming.

But I’ve spent a lot of time thinking about computing. Back in the 1970s I studied computational semantics under David Hays, who was one of the first generation workers in machine translation. One of the things he impressed on me was the computation, real computation, is a physical process and thus subject to physical constraints. Too much talk about computation and information and the like treats them as immaterial substances, Cartesian res cogitans. Back in those days I bought a textbook on microprocessor design and read through several chapters. Of course what I got out of the exercise was not very deep, but it wasn’t trivial either.

Eventually I bought my first microcomputer, a North Star Horizon (this was before the days of the IBM PC). And I got a content-addressed memory board manufactured by a small (and now defunct) company started by Sidney Lamb (another first-generation MT researcher). One day the display on my computer went kerflooey (not exactly a technical term). Well, I knew that video-display boards had a synch-generator chip and it seemed to me that the problems I was having might have been caused by trouble with that chip. So I examined the circuit diagram for the video board and located the synch-generator. And then opened the box, removed the board, located the synch-generator, and reseated it. When I replaced the board and turned on the machine, the display was working fine. It’d guessed right.

That was years ago but I still remember it. Why? Because that gave me a tangible sense of the physicality of this information processing stuff. And I think all features of the story are important:

1) reading a text on microprocessor design,

2) somewhere reading about synch-generators,

3) having a problem with my machine and guessing about it’s nature,

4) consulting a circuit diagram of one board in my machine,

5) removing the board,

6) locating the chip on it,

7) reseating the chip,

8) reassembling the machine, and

9) testing it.

It’s all part of the same story. And that’s a story that informs my sense of the physicality of computing. I had to think about what I was doing at every step along the way.

That’s very different from simply believing that whatever happens in your computer is physical because, well, what else could it be? But I don’t know just how I’d characterize the knowledge I got from that experience. It’s not abstract. I hesitate to say that it’s deep or profound. But it’s very very real.