Path: utzoo!mnetor!uunet!husc6!cmcl2!phri!dasys1!andrew
From: andrew@dasys1.UUCP (Andrew Huie)
Newsgroups: comp.sys.atari.st
Subject: Re: Multitasking - A nightmare
Message-ID: <2436@dasys1.UUCP>
Date: 2 Jan 88 14:22:20 GMT
References: <2406@dasys1.UUCP>
Organization: The Big Electric Cat, NYC, NY
Lines: 35
Keywords: Multitasking Realities
Summary: Difference between real multitasking and interrupt processing

In article <2406@dasys1.UUCP>, larryw@dasys1.UUCP (Winston Lawrence) writes:
> 
>   I think that this discussion is a little off-base in many ways. Would this be going on if we were debating the benefits of disk versus cassette storage?
>   You will be hard pressed to find ANY microcomputer of recent vintage that 
>does NOT multitask to some extent. The Atari 8bits use multitasking. The ANTIC 
>CPU interrupts the 6502 chip to generate the video. Smart programs turn OFF the
>multitasking during cpu intensive stuff (compiles for example) to speed things 

I think you're confusing interrupt processing with full multitasking. One 
question you can ask yourself is: Can I run more than one program from the
same microprocessor? Or can I interchange programs between processors?
The answer: NO. Each chip is only capable of dealing with one task at a time,
and only a task specific to that chip. A real multitasking machine can have
the microprocessor (e.g. 68000) deal with more than one task on a revolving 
basis, using priorities to see who gets more time, without having to wait for
each task to finish completely before starting the next one. If the computer
isn't too slow or weighted down (with tasks), this can appear to the user as if 
each task is running at exactly the same time.

>works in a similar manner for the sound output. Disk controllers use dedicated 
>chips (and DMA) to do their thing while the CPU does its thing. ON PCs, IRMA 
>boards handle screen i/o and updates IN THE BACKGROUND, regardless of what you 
>are doing in DOS. While you might split hairs as to whether this is multitasking,
> parallel processing, or networking. Its a moot point. Multitasking is real,
> is here, and has been a feature on most micros for the last six or seven years.
If you want to call interrupt processing multitasking, then of course computers
have had it for many years, but it definitely isn't the kind that's going to,
by itself, allow you to run more than one of your favorite applications at the
same time.

> 
> -- 
> Winston Lawrence                 {allegra,philabs,cmcl2}!phri\
> Big Electric Cat Public Unix           {bellcore,cmcl2}!cucard!dasys1!larryw
> New York, NY, USA                               {sun}!hoptoad/