Instead, he would pull the instruction into a machine register,
add one to its address,
and store it back.
He would then execute the modified instruction
right from the register.
The loop was written so this additional execution time
was taken into account —-
just as this instruction finished,
the next one was right under the drum's read head,
ready to go.
But the loop had no test in it.
The vital clue came when I noticed the index register bit, the bit that lay between the address and the operation code in the instruction word, was turned on —- yet Mel never used the index register, leaving it zero all the time. When the light went on it nearly blinded me.
He had located the data he was working on near the top of memory —- the largest locations the instructions could address —- so, after the last datum was handled, incrementing the instruction address would make it overflow. The carry would add one to the operation code, changing it to the next one in the instruction set: a jump instruction. Sure enough, the next program instruction was in address location zero, and the program went happily on its way.
I haven't kept in touch with Mel,
so I don't know if he ever gave in to the flood of
change that has washed over programming techniques
since those long-gone days.
I like to think he didn't.
In any event,
I was impressed enough that I quit looking for the
offending test,
telling the Big Boss I couldn't find it.
He didn't seem surprised.
When I left the company, the blackjack program would still cheat if you turned on the right sense switch, and I think that's how it should be. I didn't feel comfortable hacking up the code of a Real Programmer.
This is one of hackerdom's great heroic epics, free verse or no. In a few spare images it captures more about the esthetics and psychology of hacking than all the scholarly volumes on the subject put together. For an opposing point of view, see the entry for {real programmer}.
[1992 postscript —- the author writes: "The original submission to the net was not in free verse, nor any approximation to it —- it was straight prose style, in non-justified paragraphs. In bouncing around the net it apparently got modified into the `free verse' form now popular. In other words, it got hacked on the net. That seems appropriate, somehow.">[
:Appendix B: A Portrait of J. Random Hacker *******************************************
This profile reflects detailed comments on an earlier `trial balloon' version from about a hundred USENET respondents. Where comparatives are used, the implicit `other' is a randomly selected segment of the non-hacker population of the same size as hackerdom.
An important point: Except in some relatively minor respects such as slang vocabulary, hackers don't get to be the way they are by imitating each other. Rather, it seems to be the case that the combination of personality traits that makes a hacker so conditions one's outlook on life that one tends to end up being like other hackers whether one wants to or not (much as bizarrely detailed similarities in behavior and preferences are found in genetic twins raised separately).