Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!lll-winken!uunet!ncrlnk!ncrcae!hubcap!rchampe
From: rchampe@hubcap.clemson.edu (Richard Champeaux)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Official Warnings...
Summary: why don't you just use BSET
Message-ID: <5188@hubcap.clemson.edu>
Date: 20 Apr 89 17:21:43 GMT
References: <43928@tut.cis.ohio-state.edu> <6634@cbmvax.UUCP> <757@manta.NOSC.MIL>
Distribution: na
Organization: Clemson University, Clemson, SC
Lines: 20

In article <757@manta.NOSC.MIL>, dwi@manta.NOSC.MIL (Steve Stamper) writes:
> Does this mean I can use the TAS instruction safely in programs which
> are designed to run only on the A2620 equipped systems, like programs
> for my own use?
> 
> -Roger Uzun

     Why don't you just use BSET.  It will perform the same function, and
I believe it doesn't take any more bytes.  The TAS instruction was designed
to be used in multiprocessor systems.  It keeps the Address Strobe low so
that another processor can't access the memory in the middle of the 
instruction; even with most multiport memories.  The BSET command is
a little more friendly, however.  It also tests the bit before setting it,
but it allows the bus to taken by another device in the middle of the
instruction.  It will still work for semaphores in a single processor
system, since the 68000 will not service an interrupt until the completion
of the current instruction.

Rich Champeaux
Clemson University