[TUHS] OS for IBM PC (was: Algol68 vs. C at Bell Labs)

Clement T. Cole clemc at ccc.com
Tue Jul 5 07:12:21 AEST 2016

Thoth Thucks ....

Actually to give Mike Malcom created Thoth ney QNX was very slick.  I agree with Larry. It was very impressive at the time.  So between Thoth (which was Unix-similar) and Minix (which was V7 Unix API clone) I think it is safe to say there are reasonable existance proofs for saying V7 was quite possible on the 8086/8088 family. 

Sent from my iPad

> On Jul 4, 2016, at 2:13 PM, Larry McVoy <lm at mcvoy.com> wrote:
> QNX, which wasn't Unix compat at the time but sorta close, in the mid
> 1980's was very very small and ran just fine on a 80286.  If my memory
> serves me correctly I had 4-10 people logged into that box on terminals.
> QNX, at least until they put real posix conformance in it, was a really
> tiny micro kernel with the rest of the os in processes.  It fit in a 
> 4K instruction cache with room to spare.
> QNX, in my opinion, is the only really interesting and commercially
> proven microkernel.
>> On Mon, Jul 04, 2016 at 12:54:15PM -0400, Norman Wilson wrote:
>> Greg Lehey:
>>  And why?  Yes, the 8088 was a reasonably fast processor, so fast that
>>  they could slow it down a little so that they could use the same
>>  crystal to create the clock both for the CPU and the USART.  But the
>>  base system had only 16 kB memory, only a little more than half the
>>  size of the 6th Edition kernel.  Even without the issue of disks
>>  (which could potentially have been worked around) it really wasn't big
>>  enough for a multiprogramming OS.
>> =====
>> Those who remember the earliest UNIX (even if few of us have
>> used it) might disagree with that.  Neither the PDP-7 nor the
>> PDP-11/20 on which UNIX was born had memory management: a
>> context switch was a swap.  That would have been pretty slow
>> on floppies, so perhaps it wouldn't have been saleable, but
>> it was certainly possible.
>> In fact Heinz Lycklama revived the idea in the V6 era to
>> create LSX, a UNIX for the early LSI-11 which had no
>> memory management and a single ca. 300kiB floppy drive.
>> It had more memory than the 8088 system, though: 20kiW,
>> i.e. 40kiB.  Even so, Lycklama did quite a bit of work to
>> squeeze the kernel down, reduce the number of processes
>> and context switches, and so on.
>> Here's a link to one of his papers on the system:
>> https://www.computer.org/csdl/proceedings/afips/1977/5085/00/50850237.pdf
>> I suspect it would have been possible to make a XENIX
>> that would have worked on that hardware.  Whether it
>> would have worked well enough to sell is another question.
>> Norman Wilson
>> Toronto ON
> -- 
> ---
> Larry McVoy                     lm at mcvoy.com             http://www.mcvoy.com/lm 

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