Path: utzoo!attcan!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!ucsd!ucrmath!rhyde
From: rhyde@ucrmath.ucr.edu (randy hyde)
Newsgroups: comp.sys.apple2
Subject: Re: Multitasking on a II
Message-ID: <10739@ucrmath.ucr.edu>
Date: 21 Dec 90 07:29:24 GMT
References: <289@generic.UUCP> <1990Dec20.143649.11598@world.std.com> <1990Dec20.184254.16292@nntp-server.caltech.edu>
Organization: University of California, Riverside
Lines: 11

>> Whoever said INC/DEC were useless for this ...

ProDOS is not using INC/DEC to prevent entry into a critical region and the
(whoops, in the) TSB/
TRB sense.  They are used to implement a variant of the Bakery algorithm
(which doesn't require uninterruptable instructions).  If you can come
up with some code to protect a crtical region using only INC or DEC as
a test and set instruction I'd be interested in seeing it (I'm not being
facetious, I really don't know if it can be done, although I tend to doubt
it).
*** Randy Hyde