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* [TUHS] New: The Earliest UNIX Code - From the Collection of the Software History Center, Computer History Museum
@ 2019-10-17 19:21 Lyle Bickley
  2019-10-17 20:44 ` [TUHS] Space Travel, was New: The Earliest UNIX Code Warren Toomey
  2019-10-18  4:52 ` [TUHS] New: The Earliest UNIX Code - From the Collection of the Software History Center, Computer History Museum William Corcoran
  0 siblings, 2 replies; 31+ messages in thread
From: Lyle Bickley @ 2019-10-17 19:21 UTC (permalink / raw)
  To: tuhs

THE EARLIEST UNIX CODE: AN ANNIVERSARY SOURCE CODE RELEASE
http://bit.ly/31pWcvM

Cheers,
Lyle
-- 
73   NM6Y
Bickley Consulting West Inc.
https://bickleywest.com

"Black holes are where God is dividing by zero"

^ permalink raw reply	[flat|nested] 31+ messages in thread
* [TUHS] Space Travel, was New: The Earliest UNIX Code
@ 2019-10-18 11:52 Doug McIlroy
  2019-10-18 18:36 ` Steffen Nurpmeso
  2019-10-26 15:10 ` Lars Brinkhoff
  0 siblings, 2 replies; 31+ messages in thread
From: Doug McIlroy @ 2019-10-18 11:52 UTC (permalink / raw)
  To: tuhs

> 10-36-55.pdf    user-mode programs: pool game

This game, written by ken, used the Graphic 2. One of its
earliest tests--random starting positions and velocities on
a frictionless table with no collision detection--produced
a mesmerizing result. This was saved in a program called
"weird1", which was carried across to the PDP11.

Weird1 was a spectacular accidental demonstration of structure
in pseudo-random numbers. After several minutes the dots
representing pool balls would evanescently form short local
alignments.  Thereafter from time to time ever-larger alignments
would materialize. Finally in a grand climax all the balls
converged to a single point.

It was stunning to watch perfect order emerge from apparent
chaos.  One of my fondest hopes is to see weird1 revived.

Doug

^ permalink raw reply	[flat|nested] 31+ messages in thread
* Re: [TUHS] Space Travel, was New: The Earliest UNIX Code
@ 2019-10-19 13:13 Doug McIlroy
  0 siblings, 0 replies; 31+ messages in thread
From: Doug McIlroy @ 2019-10-19 13:13 UTC (permalink / raw)
  To: tuhs

Apropos of OCR on shabby typewriting, I've had good luck with doing
the OCR twice with the paper differently positioned, then using diff
to spot discrepancies. For a final proofreading, a team of two--one
reading the original aloud, the other checking the copy, works much
faster and more accurately than a single person checking side-by-side
texts.

Doug

^ permalink raw reply	[flat|nested] 31+ messages in thread
* Re: [TUHS] Space Travel, was New: The Earliest UNIX Code
@ 2019-10-19 14:40 Doug McIlroy
  2019-10-19 18:32 ` Abhinav Rajagopalan
  0 siblings, 1 reply; 31+ messages in thread
From: Doug McIlroy @ 2019-10-19 14:40 UTC (permalink / raw)
  To: tuhs, dbrock

I was about to add a footnote to history about
how the broad interests and collegiality of
Bell Labs staff made Space Travel work, when
I saw that Ken beat me to telling how he got
help from another Turing Award winner.

> while writing "space travel,"
> i could not get the space ship integration
> around a planet to keep from either gaining or
> losing energy due to floating point errors.
> i asked dick hamming if he could help. after
> a couple hours, he came back with a formula.
> i tried it and it worked perfectly. it was some
> weird simple double integration that self
> corrected for fp round off. as near as i can
> ascertain, the formula was never published
> and no one i have asked (including me) has
> been able to recreate it.

If I remember correctly, the cause of Ken's
difficulty was not roundoff error. It
was discretization error in the integration
formula--probably f(t+dt)=f(t)+f'(t)dt.
Dick saw that the formula did not conserve
energy and found an alternative that did.

^ permalink raw reply	[flat|nested] 31+ messages in thread

end of thread, other threads:[~2019-10-29  2:19 UTC | newest]

Thread overview: 31+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-10-17 19:21 [TUHS] New: The Earliest UNIX Code - From the Collection of the Software History Center, Computer History Museum Lyle Bickley
2019-10-17 20:44 ` [TUHS] Space Travel, was New: The Earliest UNIX Code Warren Toomey
2019-10-17 22:39   ` Warner Losh
2019-10-17 22:51     ` Warren Toomey
2019-10-18  5:59       ` Lars Brinkhoff
2019-10-18  9:30         ` SPC
2019-10-18 17:36         ` Nemo
2019-10-18  3:01   ` Warren Toomey
2019-10-18  5:07   ` Lars Brinkhoff
2019-10-18  5:10     ` Lars Brinkhoff
2019-10-18 13:37       ` Warner Losh
2019-10-18  7:40   ` [TUHS] File system salvager, "salv" Lars Brinkhoff
2019-10-18 14:28     ` Clem Cole
2019-10-18  4:52 ` [TUHS] New: The Earliest UNIX Code - From the Collection of the Software History Center, Computer History Museum William Corcoran
2019-10-18  5:02   ` Lyle Bickley
2019-10-18 11:52 [TUHS] Space Travel, was New: The Earliest UNIX Code Doug McIlroy
2019-10-18 18:36 ` Steffen Nurpmeso
2019-10-18 20:19   ` SPC
2019-10-18 22:04     ` Ken Thompson via TUHS
2019-10-18 23:20       ` Arthur Krewat
2019-10-19  0:57         ` G. Branden Robinson
2019-10-19  1:11           ` Arthur Krewat
2019-10-29  2:18       ` Lawrence Stewart
2019-10-26 15:10 ` Lars Brinkhoff
2019-10-19 13:13 Doug McIlroy
2019-10-19 14:40 Doug McIlroy
2019-10-19 18:32 ` Abhinav Rajagopalan
2019-10-19 18:44   ` Abhinav Rajagopalan
2019-10-19 19:19   ` Clem Cole
2019-10-19 19:50     ` Henry Bent
2019-10-19 20:24       ` Arthur Krewat

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