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From: cmt@myrias.UUCP (Chris Thomson)
Newsgroups: net.arch
Subject: Re:  Memory Rules of Thumb (really IBM 370 wait state)
Message-ID: <193@myrias.UUCP>
Date: Fri, 29-Nov-85 16:43:38 EST
Article-I.D.: myrias.193
Posted: Fri Nov 29 16:43:38 1985
Date-Received: Sat, 30-Nov-85 06:40:44 EST
References: <794@ecsvax.UUCP> <306@polaris.UUCP>
Organization: Myrias Research, Edmonton
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Josh Knight writes:
> IBM 370's have a "wait state" that the operating system can use to wait for 
> interrupts rather than a "busy wait loop" if it wants to.  On the other hand
> a "busy wait loop" with interrupts enabled will work just as well on a 370
> as any other architecture.

Yes, it is true that you can busy wait on a 370, but it's a dumb idea.  Not
only does it slow down your i/o channels, but it makes it impossible to
give interrupts to the less busy cpu in a dyadic configuration.