Wednesday, May 30, 2007

powers of two

Knuth Check
Originally uploaded by dyoo
One of my friends complained that I didn't put any interesting images on my blog. So I promised him I'd post something with an image on it. I thought this photo would bring a smile to his face.

Gotta love powers of two.



Blogger Jay McCarthy said...

You have to say what the fix you found was.

9:21 AM  
Blogger Danny Yoo said...

The bug was Knuth's translation of "Hello World" into MMIX opcodes in Fascicle 1 of TAOCP.

For fun, I had written a disassembler for MMIX and hand-compared the opcodes in the book versus the ones from the disassembled binary. To my great surprise, a few of the opcodes didn't match up!

Knuth explained that the opcodes had changed in some revision, and that he had forgotten to update the book example appropriately.

11:45 PM  

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