Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!leah!bingvaxu!sunybcs!ugkamins
From: ugkamins@sunybcs.uucp (John Kaminski)
Newsgroups: comp.sys.amiga.tech
Subject: Re: CHIP mem mystery code
Message-ID: <5482@cs.Buffalo.EDU>
Date: 26 Apr 89 02:20:28 GMT
References: <17545@cup.portal.com>
Sender: nobody@cs.Buffalo.EDU
Reply-To: ugkamins@sunybcs.UUCP (John Kaminski)
Organization: SUNY/Buffalo Computer Science
Lines: 26

In article <17545@cup.portal.com> silver@cup.portal.com (Jim B Howard) writes:
=>
=> I have been having trouble with the following asm code that is
=>driving me NUTS.  The code works perfectly, as long as it is 
=>not in CHIP mem.  If its in any form of FAST mem, it functions.
            .
            .
            .
=>	btst	#6,$bfe001

As I undestand it, ANY of the 680x0 instructions that expect to be in full
control are in serious trouble, and if I recall (from long ago) correctly,
"btst" is one such instruction.  Very simply, the 680x0 is NOT guaranteed
RAM access at any time.  Therefore, when working in CHIP memory, all sorts
of DMA can be performed which the 680x0 did not expect.  Also, is it really
necessary to be waiting in such a tight loop?  Cannot the process sleep
while waiting for whatever?

---
a-WYSIWYG, a-WYSIWIG
a-WYSIWYG, a-WYSIWIG
a-WYSIWYG, a-WYSIWIG
a-WYSIWYG, a-WYSIWIG
In the jungle
The silicon jungle
The process sleeps tonight