My very bright 13-year-old nephew would like to learn computer programming (from scratch). He's quite familiar with using software,

Dan, there are some kids where the absolutely best place to start would be the console toggle switches and indicator lamps on an ancient mainframe, if you can find a live one in a computer museum, e.g. There are other kids who take best to the opposite extreme, say generic functions (object-oriented LISP). For a certain concrete thinker, I'm planning the following first program: Combine Macsyma's string manipulation functions, especially CARDINAL_STRING (12 -> "twelve") and ORDINAL_STRING (12 -> "twelfth") to make a FRACTION_STRING function (11/12 -> "eleven twelfths"). There are nice opportunities for bugs ("one twelfths", 1/2 -> "one second", 3 -> "three firsts") and features (improper vs proper format, "three quarters"), generalization (RATIONAL_STRING, NUMBER_STRING even taking floats), and finally Robinson Crusoeing one's own CARDINAL_ and ORDINAL_ STRINGs. (Captious: "third", "thirteenth", "twenty third".) --rwg

I said

Dan, there are some kids where the absolutely best place to start would be the console toggle switches and indicator lamps on an ancient mainframe, if you can find a live one in a computer museum, e.g.

The most amazing console I ever touched was the UNIVAC 1206 (a clone of a Seymour Cray design). Every flipflop in the CPU had a neon illuminated, complementing pushbutton. You could actually compute 1!, 2!, 3!, ... with ZERO instructions in memory, just by pressing single cycle after putting the CPU in a mode called Repeat Advance, with multiply-immediate 1 in the instruction register. Actually, there was one non-neon flipflop: FAULT. It was Big and Red and Shameful. The only way to turn it out was with the RESET button, which cleared every flipflop in the CPU unless the RUN light was on, whereupon it did nothing but extinguish the glaring FAULT of shame. A closely guarded secret, told only to a few Advanced Programmers, was that executing an unused op code, besides turning on FAULT, trapped to a fixed location and saved the processor state, just like the PDP-1 cal instruction, or the PDP-6,-10 U(n)U(sed)O(p), which eventually became the way to call the operaing system. But there were no operating systems on the early machines, nor were there stack-oriented subroutine calls, until the PDP-6. Few machine-language programmers understood the incredible benefits of a stack, but those who did rolled their own, using what PDP-1 people called a "cal handler". It was probably Cray's intent for UNIVAC to follow suit, but he left in disgust before convincing the UNIVAC Oberkommandants of the idea. Another little-known fact was that you could run the machine without clearing the FAULT light. Faced with a numerical triple integral with integrals in the limits, I wrote a recursive Simpson's rule which FAULTed every few milliseconds. The resident tweedy, pipe-smoking, infinitely self-assured Advanced Programmer (first name Fritz!) walked into the machine room and said, "Your program faulted," a UNIVACkers worst fear. I just said "Yep" and went on reading my Flexowriter listing. "Ah, I get it," he smiled, and walked over and pressed RESET, apparently expecting me to freak at the prospect of losing many cpu minutes, but instead, his smile disappeared when the light didn't even flicker. "You're wasting valuable machine time." "No I'm not." Whereupon he left to confer with my boss. By the time they returned, I had my answer (a submarine kill probability), and my boss deciding he didn't even need an explanation, shrugged and left, leaving Fritz to wonder if the whole thing was a trap. --rwg

There was a private request for another early 60s computer story, and the UNIVAC tale had a sequel that might entertain some funsters. We were not allowed to list classified data on the Flexowriters because each character's binary code energized a distinct set of solenoids, broadcasting a signal that, in principal, could be decoded at a considerable distance. I seriously doubt (but dearly hope) the KGB expended the resources to intercept my Simpson's rule printout. If they ever figured out how it worked, the mathematics contained a completely fallacious model of our sensors, and the fancy programming gave the monstrous misimpression that we knew what we were doing. In fact, the Systems Analysts flatly rejected my computation, and very rudely told me to go back and try again. But I was sure of my results, and even surer that the analysts were bozos. These were the guys who spent over a year coming up with a way to intersect three ellipsoids. One of them once accused me of "ruining the randomness" by scaling uniform Monte Carlo variables instead of retrying until I got one in the desired range. He later demanded to know why the sum of two logarithms wasn't the log of the sum. I finally got some high-level director to force the bozos to show me the math behind their disputed integral. It turned out they were using a decaying Gaussian to model a distribution whose actual density was zero outside an annulus with an expanding hole whose center was the mode of their Gaussian. --rwg

Quoting Eugene Salamin <gene_salamin@yahoo.com>:

You could give C a try. He can begin to program in C using just the simplest programming concepts, and gradually augment his knowledge. Since C is a language used by professional software engineers, none of the experience would go to waste.

--- Daniel Asimov <dasimov@earthlink.net> wrote:

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My very bright 13-year-old nephew would like to learn computer programming (from scratch). He's quite familiar with using software, ...

How about good old LISP? It seems to me that the problem is not so much to find a nice language; they abound. It is to get that language into a nice environment where it can be used and experimented with. That means having a favorable operating system on a reliable computer, and it certainly wouldn't hurt to have an understandable operating manual or introduction (or even a sympathetic uncle). I've got students maybe 50% older and of who knows what brilliance, but the same problem exists. ... Good luck! - hvm ------------------------------------------------- www.correo.unam.mx UNAMonos Comunicándonos