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From: aglew@ccvaxa.UUCP
Newsgroups: net.arch
Subject: Re: timing loops
Message-ID: <5100011@ccvaxa>
Date: Sun, 23-Feb-86 22:55:00 EST
Article-I.D.: ccvaxa.5100011
Posted: Sun Feb 23 22:55:00 1986
Date-Received: Fri, 28-Feb-86 01:09:26 EST
References: <530@hoptoad.uucp>
Lines: 27
Nf-ID: #R:hoptoad.uucp:530:ccvaxa:5100011:000:1486
Nf-From: ccvaxa.UUCP!aglew    Feb 23 21:55:00 1986


>/* Written 11:14 pm  Feb 22, 1986 by mjs@sfsup.UUCP in ccvaxa:net.arch */
>As a kernel hacker, I would maintain that a device that requires a
>certain latency and neither rejects further commands nor signals an
>iterrupt until it's ready is a botch.  Why patch software when the
>hardware CAN do it right?  Software is not the answer to hardware
>designer ineptitude.  Even if it has to be done at the board level,
>the proper choice is to add the hardware to disable access to the
>device until its latency period is over.

As an apprentice kernel hacker (well, not quite apprentice - I'm learning by 
doing) and an aspiring hardware designer, I respond that those nice features
you want in your devices are probably provided by firmware, which is a lot
cheaper than extra hardware, and that this firmware has to be programmed in
some language. You don't want to condemn firmware programmers to always 
working in assembly, do you?

I agree that devices interfacing to a large, multiuser, UNIX system should
be well behaved, but you don't necessarily want to pay that price in small
systems - hell, on small systems you can't talk so blithely about the board
level, boards are damned expensive. And even on large systems, there are 
devices that respond quickly enough, and for which you cannot afford the
extra delay provided by hardware lockouts, that direct control is necessary.

Andy "Krazy" Glew. Gould CSD-Urbana. 
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