Hackers, Heroes of the Computer Revolution - Steven Levy (top books to read txt) 📗

what part of your program the computer was working on. You would have to discern this, though, over the clacking of the Flexowriter, which could make you think you were in the middle of a machine-gun battle. Even more amazing was that, because of these “interactive” capabilities, and also because users seemed to be allowed blocks of time to use the TX-0 all by themselves, you could even modify a program WHILE

SITTING AT THE COMPUTER. A miracle!

 

There was no way in hell that Kotok, Saunders, Samson, and the others were going to be kept away from that machine.

Fortunately, there didn’t seem to be the kind of bureaucracy surrounding the TX-0 that there was around the IBM 704. No cadre of officious priests. The technician in charge was a canny white-haired Scotsman named John McKenzie. While he made sure that graduate students and those working on funded projects—

Officially Sanctioned Users—maintained access to the machine, McKenzie tolerated the crew of TMRC madmen who began to hang out in the RLE lab, where the TX-0 stood.

 

Samson, Kotok, Saunders, and a freshman named Bob Wagner soon figured out that the best time of all to hang out in Building 26

was at night, when no person in his right mind would have signed up for an hour-long session on the piece of paper posted every Friday beside the air conditioner in the RLE lab. The TX-0 as a rule was kept running twenty-four hours a day—computers back then were too expensive for their time to be wasted by leaving them idle through the night, and besides, it was a hairy procedure to get the thing up and running once it was turned off.

So the TMRC hackers, who soon were referring to themselves as TX-0 hackers, changed their life-style to accommodate the computer. They laid claim to what blocks of time they could, and would “vulture time” with nocturnal visits to the lab on the off chance that someone who was scheduled for a 3 A.M. session might not show up.

 

“Oh!” Samson would say delightedly, a minute or so after someone failed to show up at the time designated in the logbook. “Make sure it doesn’t go to waste!”

 

It never seemed to, because the hackers were there almost all the time. If they weren’t in the RLE lab waiting for an opening to occur, they were in the classroom next to the TMRC clubroom, the Tool Room, playing a “hangman”-style word game that Samson had devised called “Come Next Door,” waiting for a call from someone who was near the TX-0, monitoring it to see if someone had not shown up for a session. The hackers recruited a network of informers to give advance notice of potential openings at the computer—if a research project was not ready with its program in time, or a professor was sick, the word would be passed to TMRC

and the hackers would appear at the TX-0, breathless and ready to jam into the space behind the console.

 

Though Jack Dennis was theoretically in charge of the operation, Dennis was teaching courses at the time, and preferred to spend the rest of his time actually writing code for the machine.

Dennis played the role of benevolent godfather to the hackers: he would give them a brief hands-on introduction to the machine, point them in certain directions, be amused at their wild programming ventures. He had little taste for administration, though, and was just as happy to let John McKenzie run things.

McKenzie early on recognized that the interactive nature of the TX-0 was inspiring a new form of computer programming, and the hackers were its pioneers. So he did not lay down too many edicts.

 

The atmosphere was loose enough in 1959 to accommodate the strays—science-mad people whose curiosity burned like a hunger, who like Peter Samson would be exploring the uncharted maze of laboratories at MIT. The noise of the air-conditioning, the audio output, and the drill-hammer Flexowriter would lure these wanderers, who’d poke their heads into the lab like kittens peering into baskets of yarn.

 

One of those wanderers was an outsider named Peter Deutsch. Even before discovering the TX-0, Deutsch had developed a fascination for computers. It began one day when he picked up a manual that someone had discarded, a manual for an obscure form of computer language for doing calculations. Something about the orderliness of the computer instructions appealed to him: he would later describe the feeling as the same kind of eerily transcendent recognition that an artist experiences when he discovers the medium that is absolutely right for him. THIS IS WHERE I BELONG.

Deutsch tried writing a small program, and, signing up for time under the name of one of the priests, ran it on a computer.

Within weeks, he had attained a striking proficiency in programming. He was only twelve years old.

 

He was a shy kid, strong in math and unsure of most everything else. He was uncomfortably overweight, deficient in sports, but an intellectual star performer. His father was a professor at MIT, and Peter used that as his entree to explore the labs.

 

It was inevitable that he would be drawn to the TX-0. He first wandered into the small “Kluge Room” (a “kluge” is a piece of inelegantly constructed equipment that seems to defy logic by working properly), where three off-line Flexowriters were available for punching programs onto paper tape which would later be fed into the TX-0. Someone was busy punching in a tape.

Peter watched for a while, then began bombarding the poor soul with questions about that weird-looking little computer in the next room. Then Peter went up to the TX-0 itself, examined it closely, noting how it differed from other computers: it was smaller, had a CRT display, and other neat toys. He decided right then to act as if he had a perfect right to be there. He got hold of a manual and soon was startling people by spouting actual make-sense computer talk, and eventually was allowed to sign up for night and weekend sessions, and to write his own programs.

 

McKenzie worried that someone might accuse him of running some sort of summer camp, with this short-pants little kid, barely tall enough to stick his head over the TX-O’s console, staring at the code that an Officially Sanctioned User, perhaps some self-important graduate student, would be hammering into the Flexowriter, and saying in his squeaky, preadolescent voice something like “Your problem is that this credit is wrong over here … you need this other instruction over there,” and the self-important grad student would go crazy—WHO IS THIS LITTLE

WORM?—and start screaming at him to go out and play somewhere.

Invariably, though, Peter Deutsch’s comments would turn out to be correct. Deutsch would also brazenly announce that he was going to write better programs than the ones currently available, and he would go and do it.

 

Samson, Kotok, and the other hackers accepted Peter Deutsch: by virtue of his computer knowledge he was worthy of equal treatment. Deutsch was not such a favorite with the Officially Sanctioned Users, especially when he sat behind them ready to spring into action when they made a mistake on the Flexowriter.

These Officially Sanctioned Users appeared at the TX-0 with the regularity of commuters. The programs they ran were statistical analyses, cross correlations, simulations of an interior of the nucleus of a cell. Applications. That was fine for Users, but it was sort of a waste in the minds of the hackers. What hackers had in mind was getting behind the console of the TX-0 much in the same way as getting in behind the throttle of a plane, Or, as Peter Samson, a classical music fan, put it, computing with the TX-0 was like playing a musical instrument: an absurdly expensive musical instrument upon which you could improvise, compose, and, like the beatniks in Harvard Square a mile away, wail like a banshee with total creative abandon.

 

One thing that enabled them to do this was the programming system devised by Jack Dennis and another professor, Tom Stockman. When the TX-0 arrived at MIT, it had been stripped down since its days at Lincoln Lab: the memory had been reduced considerably, to 4,096 “words” of eighteen bits each. (A “bit” is a BInary digiT, either a one or zero. These binary numbers are the only thing computers understand. A series of binary numbers is called a “word.”) And the TX-0 had almost no software. So Jack Dennis, even before he introduced the TMRC people to the TX-0, had been writing “systems programs”—the software to help users utilize the machine.

 

The first thing Dennis worked on was an assembler. This was something that translated assembly language—which used three-letter symbolic abbreviations that represented instructions to the machine—into machine language, which consisted of the binary numbers 0 and 1. The TX-0 had a rather limited assembly language: since its design allowed only two bits of each eighteen-bit word to be used for instructions to the computer, only four instructions could be used (each possible two-bit variation—00, 0 1, 10, and 11—represented an instruction).

Everything the computer did could be broken down to the execution of one of those four instructions: it took one instruction to add two numbers, but a series of perhaps twenty instructions to multiply two numbers. Staring at a long list of computer commands written as binary numbers—for example, 10011001100001—

could make you into a babbling mental case in a matter of minutes. But the same command in assembly language might look like this: ADD Y. After loading the computer with the assembler that Dennis wrote, you could write programs in this simpler symbolic form, and wait smugly while the computer did the translation into binary for you, Then you’d feed that binary “object” code back into the computer. The value of this was incalculable: it enabled programmers to write in something that LOOKED like code, rather than an endless, dizzying series of ones and zeros.

 

The other program that Dennis worked on with Stockman was something even newer—a debugger. The TX-0 came with a debugging program called UT-3, which enabled you to talk to the computer while it was running by typing commands directly into the Flexowriter, But it had terrible problems-for one thing, it only accepted typed-in code that used the octal numeric system.

“Octal” is a base-eight number system (as opposed to binary, which is base two, and Arabic—ours-which is base ten), and it is a difficult system to use. So Dennis and Stockman decided to write something better than UT-3 which would enable users to use the symbolic, easier-to-work-with assembly language. This came to be called FLIT, and it allowed users to actually find program bugs during a session, fix them, and keep the program running.

(Dennis would explain that “FLIT” stood for FLexowriter Interrogation Tape, but clearly the name’s real origin was the insect spray with that brand name.) FLIT was a quantum leap forward, since it liberated programmers to actually do original composing on the machine—just like musicians composing on their musical instruments. With the use of the debugger, which took up one third of the 4,096 words of the TX-O’s memory, hackers were free to create a new, more daring style of programming.

 

And what did these hacker programs DO? Well, sometimes, it didn’t matter much at all what they did. Peter Samson hacked the night away on a program that would instantly convert Arabic numbers to Roman numerals, and Jack Dennis, after admiring the skill with which Samson had accomplished this feat, said, “My God, why would anyone want to do such a thing?” But Dennis knew why. There was ample justification in the feeling of power and accomplishment Samson got when he fed in the paper tape, monitored the lights and switches, and