Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!ukc!warwick!phupp
From: phupp@warwick.ac.uk (S Millington)
Newsgroups: comp.sys.amiga
Subject: Re: A500 w/Fatter Agnus
Message-ID: <404@lily.warwick.ac.uk>
Date: 8 Feb 90 10:49:08 GMT
References: <01904.AA01904@doug>
Reply-To: phupp@warwick.ac.uk (S Millington)
Organization: Computing Services, Warwick University, UK
Lines: 50

In article <01904.AA01904@doug> douglee@doug.UUCP (Doug Lee) writes:
>
>seamus@bucsf.UUCP (Jeff Rizzo) writes:
>
>>A question for the net... I've heard folks say it can be done, but how
>>do I get my A500 (it has the 1 Meg Agnus) to recognize the extra 512K
>>expansion (similar to the A501) as chip RAM?
>
>>   I would appreciate it if someone could email me a description of the
>>procedure...
[deleted]
>disconnect the pullup resistor from pin 32 of the Gary chip. There may be
>jumpers for one or both of these. Some versions of A500 have a jumper
[deleted]

     Yes there are jumpers:

     I did try to email this but it bounced from the rn reply option!
Anyway here goes:

    If you have the 1meg agnus I am assuming you have a rev6a board, and 1meg
fitted - in the A501 slot, I don't know what difference it makes to have
the second 512K on the main board, this experience is from a UK A500.

Two jumpers need changing:

JP2  - between 68000 and the chip to it's right, it is labeled
       it is initially linked down, towards the front of the case
       the connection down is cut and re-made to connect up

JPA7 - I'm not too sure about this name, but it is the only jumper near, it is
       right by, the A501 port.
       it too is initially linked down
       this link must be cut and left unconnected

THIS IS AT YOUR OWN RISK, CHECK THIS IS CORRECT FOR YOUR BOARD. IT WORKED FOR
MY REV6A BOARD, I AM NOT RESPONSIBLE FOR YOU DESTROYING YOURS.

     Incidentally I did not use solder to remake my link - with a 20W iron
and being totaly inept at anything smaller than a 555 it didn't seem such a
good idea. I used 'Conductive Silver Paint' from Tandy/Radio Shack, I know but
I was desperate and no-one else sold it:-)
     Good luck to anyone who tries this, but remember what a wrong connection
can do to a $450 computer, and try and get the exact same info from a few
people, or one person you KNOW is correct, before you try anything. Sorry for
all the dire consequencies stuff, but I don't want to be the cause of hundreds
of dead amigas.

Stuart Millington.
phupp@poppy.