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From: FINEBERG@WUMS2.WUSTL.EDU (Charlie Fineberg)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: More on my sick 2500/30
Message-ID: <9105302240.AA06785@wugate.wustl.edu>
Date: 30 May 91 22:58:20 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Lines: 72

Mark Gooderum was kind enough to help me specify my plight more directly...
>> Lt. Grey and nothing.  Still nothing to this very moment.
>     
>Hmmm.
>     
>> yet?  Well a friend of mine has an A2000 which is not responding to
>> horizontal mouse movements but is otherwise working.
>     
>Did he check that it is ideed the machine, and not just the mouse, and
>whether it is one or both ports?  (You can get Intuition to switch
>ports 0 and 1 with a left-Amiga-P).

  I didn't know about left-Amiga-P but I did know about setmouse2 and used
it.  It worked correctly.  But many games (and my accelerator boards rom)
don't recognize the right port...

>>  He let me swap chips
>> to find out both what is wrong with his system and with mine.  Let me list
>> what we swapped from one system to the other without changing the behaviour
>> of either machine.  (What is socketed on our mother boards?)
>>         BUSTER
>>         DENISE
>>         PAULA
>>         68000
>>         ROM
>     
>Of course the Mouse X/Y registers are on Paula.  However, the
					  ^^^^^
  The way I read the apendices of _Introduction_to_the_Amiga_2000_ (the
book that came with my 2000), it says that Paula does all of the A/D and
D/A.  So it does the audio channels the analog joystick channels and some
disk control.  Denise does the mouse ports.  The signals are M0H, M1H, M0V
and M1V.  But since I was being thorough...

>quadrature pulses go through some multiplexors before they get to
>Paula (I think).  You didn't mention the CIAs.  They don't deal with
>the X/Y but they do deal with the mouse buttons and the system time
>clocks.  My 1000 had similar problems and it turned out to be one of
>the CIAs.

Is that the mouse problem or the system hangup problem.  The mouse
quadrature signals all go through U202 which is a 74ls157.  I think that is
just a mux which is toggled (indirectly) by left_Amiga-P.

>> have 512K FANG).  Does this mean that the offender must be Agnus on my
>> board?
>     
>Well, if you system is totally hosed and refuses to boot, Agnus could
>indeed be the problem.  I wouldn't try swapping w/o a proper PLCC
>extractor though.  Agnus can take it, but the sockets tend to be fragile.

Yeah, I'm hoping I can find a GAC (Gateway Amiga Club) member who has made
the upgrade already and will let me borrow their old Agnus and the
puller...

>You also of course removed all peripheral boards, (inc. 2630) to
>elminate them as culprits?

Oops.  I should have mentioned that right off.  Yes, my current test is
with power supply and monitor attached.  Nothing else.  I can do more tests
per minute that way.

Has anyone had their system behave the way mine has and known that it is
independent of all of those chips I swapped?

>Bitnet:   MARKV@UKANVAX         \/\/  /    | |  | | |__| /   \ possible...
>Internet: markv@kuhub.cc.ukans.edu

And Mark, hurry back to the net.  Your ability to eloquently answer
questions posed (especially to i-amiga) has made it easy for me to get some
work done.  "I don't have to answer that one, Mark will!"
	Charlie 	fineberg@wums2.wustl.edu, fineberg@wums2.bitnet