Re: [TUHS] Alternative Implementation Proposal for Unix/370 (BTL, 1979)

[jnc@mercury.lcs.mit.edu (Noel Chiappa)]

    > From: Tom Lyon

    > there were a few icustomer nstallations. Bell Labs Indian Hill was one
    > - so that's why TSS was the base of their UNIX port.

"A UNIX System Implementation for System/370" (by W. A. Felton, G. L. Miller,
and J. M. Milner):

  https://www.bell-labs.com/usr/dmr/www/otherports/ibm.html

says "code to support System/370 I/O, paging, error recording and recovery,
and multiprocessing already existed in several available operating systems,
we investigated the possibility of using an existing operating system, or at
least the machine-interface parts of one, as a base to provide these
functions for the System/370 implementation ... Of the available systems,
TSS/370 came the closest to meeting our needs and was thus chosen as the base
for our UNIX system implementation". Alas, it doesn't say which other systems
were also considered.


    >> On May 6, 2022, at 09:39, arnold@skeeve.com wrote:

    >> So, why, given the letter from these folks, including DMR, did they go
    >> ahead and use the TSS solution anyway?

That paper says: "We initially thought about porting the UNIX operating
system directly to System/370 with minimal changes. Unfortunately, there are
a number of System/370 characteristics that, in the light of our objectives
and resources, made such a direct port unattractive. The Input/Output (I/O)
architecture of System/370 is rather complex; in a large configuration, the
operating system must deal with a bewildering number of channels,
controllers, and devices, many of which may be interconnected through
multiple paths. Recovery from hardware errors is both complex and
model-dependent. For hardware diagnosis and tracking, customer engineers
expect the operating system to provide error logs in a specific format;
software to support this logging and reporting would have to be written. ...
Finally, several models of System/370 machines provide multiprocessing, with
two (or more) processors operating with shared memory; the UNIX system did
not support multiprocessing."

Presumably these factors outweighed the factors listed in the
Haley/London/Maranzaro/Ritchie letter.

	Noel