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From: stever@videovax.UUCP
Newsgroups: comp.sys.amiga,comp.sys.mac,comp.sys.m68k,comp.sys.misc
Subject: Re: Mac vs. Amiga
Message-ID: <4186@videovax.Tek.COM>
Date: Mon, 26-Jan-87 10:43:50 EST
Article-I.D.: videovax.4186
Posted: Mon Jan 26 10:43:50 1987
Date-Received: Wed, 28-Jan-87 07:22:55 EST
References: <8520@topaz.RUTGERS.EDU> <1270@cbmvax.cbmvax.cbm.UUCP> <5240@ism780c.UUCP> <2312@jade.BERKELEY.EDU> <5283@ism780c.UUCP>
Reply-To: stever@videovax.Tek.COM (Steven E. Rice, P.E.)
Organization: Tektronix Television Systems, Beaverton, Oregon
Lines: 37
Xref: watmath comp.sys.amiga:1722 comp.sys.mac:967 comp.sys.m68k:174 comp.sys.misc:256

In article <5283@ism780c.UUCP>, Tim Smith (tim@ism780c.UUCP) asks for a
definition of the term "operating system," along with other questions:

John J. Donovan's definition of an operating system is:

   An operating system is concerned with the allocation of resources
   and services, such as memory, processors, devices, and information.
   The operating system correspondingly includes programs to manage
   these resources, such as a _traffic controller_, a _scheduler_,
   _memory management module_, _I/O programs_, and a _file system_.

                                   _Systems Programming_, McGraw-Hill,
                                   New York (1972), p. 15
                                   (emphasis in the original)

> . . .

> If I am running Switcher or Servant on a Mac, then I may have 
> multiple programs loaded.  Context is switched by explicit action 
> on my part, while, say, on my UNIX system, it can also be 
> switched by explicit action on the part of the clock.  I don't 
> see an essential difference as far as the operating-systemness of 
> either system goes.

The purpose of an operating system is to manage the machine's resources,
making most efficient use of them without human intervention.  In this
case, you are playing the role of "traffic controller."  Because you do
not have full knowledge of the internal state of the machine at any given
time (and because humans act on a timescale far longer than that of the
computer), you cannot manage the system resources on a millisecond-by-
millisecond basis.  According to Donovan, this is a function of the
operating system, so in this case the Mac is deficient.  

					Steve Rice

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