Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!usc!brutus.cs.uiuc.edu!jarthur!uunet!mcsun!unido!mpirbn!p554mve
From: p554mve@mpirbn.UUCP (Michael van Elst)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: Puzzling Paula!
Message-ID: <563@mpirbn.UUCP>
Date: 23 Feb 90 10:33:33 GMT
References: <736@shodha.dec.com>
Reply-To: p554mve@mpirbn.UUCP (Michael van Elst)
Organization: Max-Planck-Institut fuer Radioastronomie, Bonn
Lines: 20

In article <736@shodha.dec.com> ridder@elvira.enet.dec.com (Hans Ridder) writes:
>How is it that Paula would allow the system to boot, but fail on the
>first click of the disk icon?   Any ideas?  Commodore people?

An identical symptom showed up on my Amiga, yet it wasn't Paula but
one of the CIAs. Nevertheless, the reason for this behaviour is the
interrupt system, and this is managed by Paula AND the CIAs.

The problem arises from the attempt to synchronize rendering with
the electon beam in you monitor. One CIA clock is used to time
the interrupt routine excactly to the correct scanline and Paula
of course delivers the interrupt.

Now on the ususal workbench screen the synchronisation is used only
with icon movement. (I've played with the old Kick1.1, and everthing
works there because only the pointer changes when moving an icon).


Michael van Elst
uunet!unido!mpirbn!p554mve