Newsgroups: comp.sys.amiga.tech
Path: utzoo!utgpu!jarvis.csri.toronto.edu!dgp.toronto.edu!pavel
From: pavel@dgp.toronto.edu (Pavel Rozalski)
Subject: Re: Official Warnings...
Message-ID: <8904302141.AA21035@explorer.dgp.toronto.edu>
Keywords: tas
Organization: University of Toronto, CSRI
References: <3082@haven.umd.edu> <11394@well.UUCP> <3773@sugar.hackercorp.com> <10819@mcdphx.phx.mcd.mot.com>
Distribution: na
Date: Sun, 30 Apr 89 17:41:54 EDT

In article <10819@mcdphx.phx.mcd.mot.com> dbk@teroach.UUCP (Dave Kinzer) writes:
>In article <3773@sugar.hackercorp.com> karl@sugar.hackercorp.com (Karl Lehenbauer) writes:
>>
>>Isn't TAS useful on a single CPU system, though, for providing fast,
>>uninterruptable test and set for use as a semaphore, without having 
>>to turn off interrupts?
>>
>>-- uunet!sugar!karl  | "Nobody hipped me to that, dude." -- Pee Wee
>>-- Usenet BBS (713) 438-5018
>
>   Semaphore to who?  Another task?   That's what the operating system is
>in there for.  It takes care of all the system dependent stuff.  
>
>   I think (really) that this whole discussion boils down to:  The TAS
>instruction should not be used in an Amiga because it has a problem with
>the custom chips.  YOU WERE WARNED!  That's it, end of any discussion
>appropriate to this newsgroup.

Occasionally one may wish to have a lightweight method of accessing
shared memory without the burden of an OS call. Seems as if Motorola
would have provided the TAS in the 68000 series for that purpose.

Pavel Rozalski
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