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From: ac4@pucc-j (Tom Putnam)
Newsgroups: net.micro,net.arch
Subject: Re: Apple's IWM; Floppy Disk Controllers
Message-ID: <724@pucc-j>
Date: Thu, 16-Jan-86 09:53:42 EST
Article-I.D.: pucc-j.724
Posted: Thu Jan 16 09:53:42 1986
Date-Received: Sat, 18-Jan-86 06:56:11 EST
References: <382@ncr-sd.UUCP> <1894@peora.UUCP> <364@ektools.UUCP>
Reply-To: ac4@pucc-j.UUCP (Tom Putnam)
Organization: Purdue University Computing Center
Lines: 34
Xref: watmath net.micro:13514 net.arch:2410

In article <364@ektools.UUCP> {allegra,seismo}!rochester!kodak!ektools!john (John H. Hall) writes:
>
>In a single-user, single-task environment, (such as the Apple II and the
>Mac) the ability to compute and do disk I/O concurrently is not nearly
>the big win it is in a multi-user, multi-tasking system.  For a low-end
>system such as the Apple ][ it is entirely appropriate.
>
While I don't completely disagree with his point, I think people tend to
forget that a single user on a "low-end" system may want to try to use
more than one peripheral device at a time.  Consider, for example, the
terminal emulator which is trying to capture information to disk.  If the
system has an intelligent disk controller, DMA transfer, and interrupt
driven communication, then it doesn't have to stop/suspend the (slow)
communications I/O in order to rev up the (slow) disk and write a sector.

DMA, interrrupts, and intelligent controllers are all available on well
integrated chip sets... even the 4-year old IBM PCs and clones have them.
The fact that low-end systems (particularly Apple ][) do not have these 
capabilities often means that quality software is not available to do
functions that might require concurrent I/O.  I think that's a shame.

-- 
Tom Putnam, Manager of User Services
Purdue University Computing Center

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