-----Oorspronkelijk bericht-----
From: Johnny Billquist
Sent: Sunday, March 08, 2015 9:48 PM
To: [email protected]
Subject: Re: [Simh] Regarding "Cutler THE father of VMS" myth
On 2015-03-08 21:39, Clem Cole wrote:
On Sun, Mar 8, 2015 at 8:23 AM, Sergey Oboguev <[email protected]
<mailto:[email protected]>> wrote:
If so, he may have a claim to inventing (a hint at) a microkernel
concept. ;-)
​Dykstra invented the ukernel -- its the THE kernel:
https://en.wikipedia.org/wiki/THE_multiprogramming_system
The paper itself is
http://uosis.mif.vu.lt/~liutauras/books/Dijkstra%20-%20The%20structure%20of%20the%20THE%20multiprogramming%20system.pdf
And all kernel hacker should read it some time. It where the idea of
semaphores are defined and the idea of "up" and "down" - (aka P/V).
Well, in all fairness, semaphores were used on railways already in the
19th century...
Johnny
That's true, but Dijkstra used it as a software technique, and that was new.
BTW, "up" and "down" is not the best translation for "P/V" operation.
P stands for the Dutch word "passeer" which roughly translates to "pass".
V stands for the Dutch word "verhoog" and that should be translated to
"increment". And that is exactly what happens: pass and increment (the
semaphore variable).
- Henk
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