What does unix require from a computer?

[Tom Kessler]

There are of course all sorts of questions about how much you want to pay
in performance for running unix on a small machine.

I have seen an ibm pc with a ten megabyte hard disk, and 640K of memory
running VENIX-86 (made by venturcom I believe) this version is has kernel
of ~ 240Kbytes. It is a stripped down system III with a fair number of
the Berkley enhancements. It has almost all of the usual UNIX tools
and ( purely subjective measurement ) responds about as well as
a VAX 750 with ten users editing, running a few programs,etc.
There is the disadvantage, however, that once you have put VENIX on
the hard disk, you have a only about 2 megabytes of disk space free.

There are some systems as small as a pdp11/23+ running Berkley 2.8
with 256K of memory . I know of one such system with
40 meg. of disk space that has a user population of dozen or so people
that is reputed to be a dog  when there are more than two users on 
at a time.

Right now I am using a SUN 100 with a SUN2 cpu 2 megabytes of memory
and 100 megabytes of disk space, that runs the entire BERKLEY 4.2 Unix,
and has  a kernel size of about 300K. With a single user this machine
is really quite nice however if you are into serious number crunching
it would probably not suit your purposes. 

Another thing to consider is whether or not your machine has virtual 
memory facilities. This of course allows the use of more than the real
amount of memory usually by paging onto a disk.  This of course is
a real advantage in that it allows you to use very large data and program
spaces but requires more disk space and fast disk access time.
The SUN does allow virtual address extension but neither the ibmpc
nor the pdp series do.

-- 
thanks for all the fish...

                   Tom Kessler {allegra |seismo }!rochester!ur-laser!tomk
Laboratory for Laser Energetics               Phone: (716)- 275 - 3786
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