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

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

cm.bell-labs.com

32 pointshenning12 comments

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.

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

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

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.

Hardware interrupt.

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

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/ .

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)

Is the Bob Morris he references rtm's dad?

Yes. One of the original Unix guys.

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

Hooray for programmer folklore!

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