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From: emjej@uokvax.UUCP
Newsgroups: net.micro
Subject: Re: Re: Small micro OS for Education - (nf)
Message-ID: <3400042@uokvax.UUCP>
Date: Wed, 18-Apr-84 10:36:00 EST
Article-I.D.: uokvax.3400042
Posted: Wed Apr 18 10:36:00 1984
Date-Received: Sun, 22-Apr-84 08:39:13 EST
References: <2006@ihnss.UUCP>
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Nf-ID: #R:ihnss:-200600:uokvax:3400042:000:1364
Nf-From: uokvax!emjej    Apr 18 09:36:00 1984

#R:ihnss:-200600:uokvax:3400042:000:1364
uokvax!emjej    Apr 18 09:36:00 1984

/***** uokvax:net.micro / bbncca!sdyer / 10:12 pm  Apr 14, 1984 */
>What this means is that if you're not careful, especially in a dynamic
>multi-process environment, memory gets fragmented, and processes which
>ran successfully at one point in time won't have sufficient contiguous
>memory to start up.

True, for Level One. (Too bad a CoCo won't run Level Two...)

>Especially with the advent of low
>cost hard disks, the additional system slowness of a swapping system
>might possibly be worth the increase in flexibility and predictability.

This is not a rhetorical question--how fast are those inexpensive hard
disks? I quote from Robert Gammill's "Position Paper on OS's for Small
Systems: the Unix Operating System," SIGPC Notes, v.4 no. 3, fall 1981:

	Many of the smaller Winchester disks now entering the market
	use stepper motors for head movement, providing average
	access times of 200 msec or more but keeping costs low. Others,
	using more expensive voice coil actuators, provide average
	access nearer 20 msec but at higher cost. Such differences will
	be very noticeable in Unix performance, since its performance
	under load is so disk access and main memory dependent....We
	are likely soon to begin hearing complaints from those who
	have had the bad judgement to try to run Unix on hardware
	unable to properly support it!

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