"Observations on the Development of an Operating System"page 33:
Hugh C. Lauer, Xerox Corporation, Palo Alto, California
In SOSP '81 Proceedings of the eighth ACM symposium on Operating systems principles, ACM SIGOPS Operating Systems Review, Volume 15 Issue 5, December 1981, pages 30-3. ISBN:0-89791-062-1,doi: 10.1145/800216.806588, PDF
. . . I found it useful to enumerate some of the
other operating systems I have known, either from direct contact or
from study of the literature or from contact with others. These
systems seem to fall into five categories. which I shall first enumerate
and then describe.
1. The Alto system. UNIX.
2. IBM's OS/360. MLUTICS, Pilot, etc.
3. MTS (the Michigan Terminal System). TE~EX. CP-67
4. CAL-TSS. Project SUE. HYDRA. etc.
5. DOS/360, RS-11, etc.
These categories are the result of my personal observations. nor of a
systematic study, and hence many systems are not listed because I
don't know enough about them to classify them. The ordering of
the categories is not significant. An important pan of the
classification is the maturity or success of a system-i.e .. acceptance
by its clients as a useful. economic tool for helping to get work done,
for · supporting applications, or for fulfilling other goals. A
characteristic of a successful system is that it is accepted by a nontrivial
community of users outside its developing organization as a
matter of choice and that this community contributes. directly or
indirectly, to its further development and growth.
. . .
. . .
Systems of the third kind. These systems borrow much of their
supporting software from an existmg system but represent a
fundamental change in the way of life. The Michigan Terminal
System, for example, provides a paging, terminal-oriented. time·
sharing system especially suited for university use on the IBM 360/67
and IBM 370 systems. Most of its compilers, run-time support,
subroutine libraries, program development tools. etc., were taken and
convened directly from OS/360, but its operating system kernel is
dramatically different from OS/360 and it supports new applications
that OS/360 never could. (Of course, there are also many OS/360
applications that MTS cannot support.) The obvious motivation for
building a system of this kind is to avoid the time and expense of
designing. implementing, and maintaining all new supporting
software for the operating system when it is desired only to
implement an operating system kernel and some basic functions.
. . .
[I think the above paragraph overstates how much of MTS was "borrowed". It is certainly true that many of the programming languages compilers, a number of other application programs, and some subroutine libraries in MTS were borrowed. It is not the case that most of the MTS run-time support and program development tools were borrowed. The MTS Editor, the Symbolic Debugging System (SDS), and the MTS file system are a few examples of components developed for MTS. And not all of the components that were borrowed came from OS/360, although many did. -Jeff]