From: doug@cs.dartmouth.edu (Doug McIlroy)
Subject: [TUHS] Harvard and Von Neumann Architectures and Unix
Date: Sat, 25 Nov 2017 12:34:47 -0500 [thread overview]
Message-ID: <201711251734.vAPHYlaH030631@coolidge.cs.Dartmouth.EDU> (raw)
From the discussion of self-modifying code:
>> Optimal code for bitblt (raster block transfers) in the Blit
>
> Interesting case. I'm not familiar with BitBLT codes, do they actually modify
> the existing program, or rather do they build small custom ones? Only the
> > former is what I was thinking of.
>
It built small custom fragments of code. But if that had been in D
space, it couldn't have been executed.
>> Surely JIT compiling must count as self-modifying code.
>
> If it does, then my computer just runs one program from when I turn it
> on. It switches memory formats and then is forever extending itself and
> throwing chunks away.
Exactly. That is the essence of stored-program computers. The exec
system call is self-modification with a vengeance.
Fill memory-and-execute is the grandest coercion I know. What is
data one instant is code the next.
It's all a matter of viewpoint and scale. Where is the boundary
between changing one instruction and changing them all? Or is
this boundary a figment of imagination?
Doug
next reply other threads:[~2017-11-25 17:34 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-25 17:34 Doug McIlroy [this message]
-- strict thread matches above, loose matches on Subject: below --
2017-11-27 17:11 Noel Chiappa
2017-11-28 0:23 ` Dave Horsfall
2017-11-27 16:11 Noel Chiappa
2017-11-27 16:50 ` Larry McVoy
2017-11-27 17:08 ` Clem Cole
2017-11-27 18:21 ` Lawrence Stewart
2017-11-27 18:30 ` Lars Brinkhoff
2017-11-27 18:14 ` Warner Losh
2017-11-27 18:26 ` Paul Winalski
2017-11-27 17:35 ` Ian Zimmerman
2017-11-28 14:55 ` Tim Bradshaw
2017-11-28 19:45 ` Paul Winalski
2017-11-25 14:24 Noel Chiappa
2017-11-25 15:58 ` Lawrence Stewart
2017-11-25 16:10 ` Lars Brinkhoff
2017-11-25 19:59 ` Steve Simon
2017-11-25 21:59 ` Bakul Shah
2017-11-25 3:14 Doug McIlroy
2017-11-25 4:16 ` Jon Steinhart
2017-11-25 5:17 ` ron minnich
2017-11-25 14:23 ` Ralph Corderoy
2017-11-24 21:43 Noel Chiappa
2017-11-24 21:50 ` Jon Steinhart
2017-11-25 21:55 ` William Cheswick
2017-11-25 23:15 ` Dave Horsfall
2017-11-24 22:20 ` Mike Markowski
2017-11-24 22:31 ` Dave Horsfall
2017-11-24 19:25 Will Senn
2017-11-24 19:28 ` Jon Steinhart
2017-11-27 14:50 ` Tony Finch
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