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From: jclark@sdcc6.ucsd.edu (John Clark)
Newsgroups: comp.sys.atari.st
Subject: Re: Multitasking
Message-ID: <16998@sdcc6.ucsd.edu>
Date: 26 Feb 91 03:48:12 GMT
References: <1991Feb11.151210.4010@informatik.uni-erlangen.de> <1976@lee.SEAS.UCLA.EDU> <1991Feb16.004202.26343@jato.jpl.nasa.gov>
Organization: University of California, San Diego
Lines: 15

In article <1991Feb16.004202.26343@jato.jpl.nasa.gov> vsnyder@jato.Jpl.Nasa.Gov (Van Snyder) writes:
+sucked).  The key to the performance was that Univac knew how to build a
+machine that could handle interrupts quickly (2 cycles, because there was
+an entire duplicate set of registers for the OS), and, more importantly,
+the operating system KNEW HOW TO USE INTERRUPTS.  If you implement multitasking

The Texas Instruments' 9900 microprocessor family had a Workspace Pointer.
The 'register set' r0-r15 was pointed to by this pointer in RAM. The
context switch was get new PC and LOAD WP. Unfortunately TI in their
wonderful fumble of the microprocessor line, didn't use their
corporate resources to dominate the market. The rest is history.
-- 

John Clark
jclark@ucsd.edu