Dennis Ritchie (R from K&R) explains "/* You are not expected to understand this */"

http://cm.bell-labs.com/cm/cs/who/dmr/odd.html

by henning • 18 years ago

32 12 18 years ago

cm.bell-labs.com

pmjordan2• 18 years ago

Hooray for programmer folklore!

soundsop• 18 years ago

My favourite part is about the lack of memory protection on the multi-user PDP-11/20:

When anyone was working on a program, it was considered a courtesy to yell "A.OUT?" before trying it, to warn others to save whatever they were editing.

pmjordan2• 18 years ago

Hardware interrupt.

lpgauth• 18 years ago

Great read although I'm not sure I understand the assembly part :/

henning2• 18 years ago

Low-level machine hacks can be inscrutable even when the machine they're implemented for is current. For instance, there's the infamous line from Quake source code that reads:

    i  = 0x5f3759df - ( i >> 1 ); // what the fuck?

People have tried to investigate the origin of this baffling hack and mostly failed. See, e.g., http://www.beyond3d.com/content/articles/8/ .

jmagar2• 18 years ago

That's one heck of a magic number...

The strangest one I've seen is the fast sqrt() function in SGI OpenGL source code: there's a magic step where a right bit shift is applied to a 32bit IEEE float.

(oops.. just clicked your link, looks like we're related)

noonespecial• 18 years ago

Sometimes I think I was born at the wrong time. I sure would have loved to hack in the bad old days of computing where the computer came with schematics and you understood exactly (or had a good try of it) what the machine was doing.

At least, I think I'd like it better than hoping that my motherboard can authorize itself to the drm in my graphics card so the hi-def from my own camera will play on my screen at more than 320x240.

henning2• 18 years ago

I'm sure they dreamed of a bright future where 1 Mhz, even 100 Mhz, machines were common.

dkokelley• 18 years ago

100Mhz?! Well now that would be nice but let's be reasonable here. :)

DaniFong• 18 years ago

Is the Bob Morris he references rtm's dad?

pfedor• 18 years ago

Yes. One of the original Unix guys.

jmagar2• 18 years ago

Who visits Hacker News and doesn't know that "Dennis Ritchie" is the R in "K&R"?

Dennis Ritchie (R from K&R) explains "/* You are not expected to understand this */"

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