[TUHS] PDP-7 Unix Paper

[TUHS] PDP-7 Unix Paper

[Warren Toomey]

All, my journal paper on PDP-7 Unix has just been licensed under CC-BY-SA,
so here's a link to the PDF version:
http://minnie.tuhs.org/Y5/wkt_hapop_paper.pdf

Cheers, Warren

[TUHS] PDP-7 Unix Paper

[Clem Cole]

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Awesome!! Thank you.
ᐧ

On Tue, Feb 13, 2018 at 4:48 PM, Warren Toomey <wkt at tuhs.org> wrote:

> All, my journal paper on PDP-7 Unix has just been licensed under CC-BY-SA,
> so here's a link to the PDF version:
> http://minnie.tuhs.org/Y5/wkt_hapop_paper.pdf
>
> Cheers, Warren
>
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[TUHS] PDP-7 Unix Paper

[Andy Kosela]

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On Tuesday, February 13, 2018, Clem Cole <clemc at ccc.com> wrote:

> Awesome!! Thank you.
> ᐧ
>
> On Tue, Feb 13, 2018 at 4:48 PM, Warren Toomey <wkt at tuhs.org> wrote:
>
>> All, my journal paper on PDP-7 Unix has just been licensed under CC-BY-SA,
>> so here's a link to the PDF version:
>> http://minnie.tuhs.org/Y5/wkt_hapop_paper.pdf
>>
>> Cheers, Warren
>>
>
>
I especially like the conclusion part.  'Less is more' against 'more is
more' was the underlying theme of the original UNIX.

--Andy
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[TUHS] PDP-7 Unix Paper

[Jim Capp]

All I can say is Wow!  Thanks for all the hard work to pull this out of dust bin and breath new life into a truly historic event. 

J

> On Feb 13, 2018, at 4:48 PM, Warren Toomey <wkt at tuhs.org> wrote:
> 
> All, my journal paper on PDP-7 Unix has just been licensed under CC-BY-SA,
> so here's a link to the PDF version:
> http://minnie.tuhs.org/Y5/wkt_hapop_paper.pdf
> 
> Cheers, Warren

[TUHS] PDP-7 Unix Paper

[Ken Thompson]

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outstanding.


On Tue, Feb 13, 2018 at 1:53 PM, Clem Cole <clemc at ccc.com> wrote:

> Awesome!! Thank you.
> ᐧ
>
> On Tue, Feb 13, 2018 at 4:48 PM, Warren Toomey <wkt at tuhs.org> wrote:
>
>> All, my journal paper on PDP-7 Unix has just been licensed under CC-BY-SA,
>> so here's a link to the PDF version:
>> http://minnie.tuhs.org/Y5/wkt_hapop_paper.pdf
>>
>> Cheers, Warren
>>
>
>
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[TUHS] PDP-7 Unix Paper

[Dave Horsfall]

On Wed, 14 Feb 2018, Warren Toomey wrote:

> All, my journal paper on PDP-7 Unix has just been licensed under 
> CC-BY-SA, so here's a link to the PDF version:

Wow!

I'm still astonished at the constraints those guys had to suffer:

     PDP-7 Unix provided a multitasking environment by dividing the 8K
     words of memory into two halves.  The lower half of memory was
     reserved for the kernel.  The upper half of memory was set aside for
     the currently running process.

But you try and tell the young people today that... and they won't believe 
you.

-- 
Dave Horsfall DTM (VK2KFU)  "Those who don't understand security will suffer."

[TUHS] PDP-7 Unix Paper

[Erik E. Fair]

That depends on the youngin' - the same technique was also used with the Dual Systems Version 7 Unix port to the mc68000 without an MMU in 1981: split the address space in half at 0x800000, top for kernel, bottom for running process, swap to context switch, and any reference to RAM below 0x800000 while in CPU user mode faulted, to protect the kernel from errant user code.

I can also tell you some S-100 (IEEE-696) device driver horror stories because CP/M-68k and its ilk were not multitasking like Unix and let us say that allowed the S-100 add-in board hardware designers to be ... lazy. The work-arounds in software were very ugly.

Main irritant: customers who claimed our hardware was broken because dereferencing a NULL pointer (0) resulted in a fault, rather than returning 0. "No, your C code is broken because address zero is not in the available address space of processes, and your code should not assume it is." (not a popular response from our customer service engineer). IIRC, most of the Unix code was well-behaved because it had grown up on computers with MMUs by the time we got it ... except for that issue.

Later, Dual produced a CPU board with an mc68451 MMU on it, and that helped. Sort of.

	Erik Fair

[TUHS] PDP-7 Unix Paper

[Larry McVoy]

On Wed, Feb 14, 2018 at 10:30:52AM +1100, Dave Horsfall wrote:
> I'm still astonished at the constraints those guys had to suffer:
> 
>     PDP-7 Unix provided a multitasking environment by dividing the 8K
>     words of memory into two halves.  The lower half of memory was
>     reserved for the kernel.  The upper half of memory was set aside for
>     the currently running process.
> 
> But you try and tell the young people today that... and they won't believe
> you.

Don't even get me started.  Young people think that a VM is a server.
I wrote a microbenchmark suite, lmbench, and I get people sending me
email that they get inconsistent results on their VM.

The lack of knowledge that would make someone ask about that is stunning.

[TUHS] PDP-7 Unix Paper

[Warner Losh]

On Tue, Feb 13, 2018 at 4:30 PM, Dave Horsfall <dave at horsfall.org> wrote:

> On Wed, 14 Feb 2018, Warren Toomey wrote:
>
> All, my journal paper on PDP-7 Unix has just been licensed under CC-BY-SA,
>> so here's a link to the PDF version:
>>
>
> Wow!
>
> I'm still astonished at the constraints those guys had to suffer:
>
>     PDP-7 Unix provided a multitasking environment by dividing the 8K
>     words of memory into two halves.  The lower half of memory was
>     reserved for the kernel.  The upper half of memory was set aside for
>     the currently running process.
>
> But you try and tell the young people today that... and they won't believe
> you.


Today's FreeBSD boot loader is 450k. Of course, it can read half a dozen
different file systems, supports crypto and has a Lua interpreter. Lua is
~140k of that.

FreeBSD's boot2 program is 16k in size, but can barely read a kernel into
memory from a UFS file system and jump to it....

4k words (4608 bytes) for all of unix is impressive...

Warner
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[TUHS] PDP-7 Unix Paper

[Donald ODona]

Thanks a lot!

At 13 Feb 2018 21:50:20 +0000 (+00:00) from Warren Toomey <wkt at tuhs.org>:
> All, my journal paper on PDP-7 Unix has just been licensed under CC-BY-SA,
> so here's a link to the PDF version:
> <a target="_blank" href="http://minnie.tuhs.org/Y5/wkt_hapop_paper.pdf">http://minnie.tuhs.org/Y5/wkt_hapop_paper.pdf</a>
> 
> Cheers, Warren

[TUHS] PDP-7 Unix Paper

[Donald ODona]

already 20 years ago I met a guy (masters degree, university) who never freed dynamically allocated memory. He told me he is 'instantiating a object', but had no idea what an heap is, and what dynamically allocated memory means.

At 14 Feb 2018 02:23:07 +0000 (+00:00) from Larry McVoy <lm at mcvoy.com>:
> On Wed, Feb 14, 2018 at 10:30:52AM +1100, Dave Horsfall wrote:
> > I'm still astonished at the constraints those guys had to suffer:
> > 
> >     PDP-7 Unix provided a multitasking environment by dividing the 8K
> >     words of memory into two halves.  The lower half of memory was
> >     reserved for the kernel.  The upper half of memory was set aside for
> >     the currently running process.
> > 
> > But you try and tell the young people today that... and they won't believe
> > you.
> 
> Don't even get me started.  Young people think that a VM is a server.
> I wrote a microbenchmark suite, lmbench, and I get people sending me
> email that they get inconsistent results on their VM.
> 
> The lack of knowledge that would make someone ask about that is stunning.

[TUHS] PDP-7 Unix Paper

[Donald ODona]

indeed. ;-)

At 18 Feb 2018 15:18:55 +0000 (+00:00) from Norman Wilson <norman at oclsc.org>:
> Donald ODana:
> 
>   already 20 years ago I met a guy (masters degree, university) who never
>   freed dynamically allocated memory. He told me he is 'instantiating
>   a object', but had no idea what an heap is, and what dynamically
>   allocated memory means.
> 
> ====
> 
> This is the sort of programmer for whom garbage collection was named:
> his programs are a collection of garbage.
> 
> Norman Wilson
> Toronto ON
> (In 1127-snark mode this evening)

[TUHS] PDP-7 Unix Paper

[Norman Wilson]

Donald ODana:

  already 20 years ago I met a guy (masters degree, university) who never
  freed dynamically allocated memory. He told me he is 'instantiating
  a object', but had no idea what an heap is, and what dynamically
  allocated memory means.

====

This is the sort of programmer for whom garbage collection was named:
his programs are a collection of garbage.

Norman Wilson
Toronto ON
(In 1127-snark mode this evening)