From: tim@lenti.med.umn.edu (Tim Leonard)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: 1 meg chip on A500
Date: 22 Jan 93 14:14:20 GMT
Article-I.D.: news2.C19E7x.7AK
Organization: University of Minnesota

In article <1jada3INNat4@charnel.ecst.csuchico.edu> bubblz@ecst.csuchico.edu (Boy Wonder) writes:
>And above this, it sez  Amiga 500  512k/1meg chip ram.
>
>This definately makes it look like, to upgrade to 1 meg chip, all you 
>would have to do is populate the slots, solder in a few resistors like
>the ones that are under the populated slots right now, and maybe cut/solder
>a jumper.  Does this sound unreasonable?  
>
>VERY curious, 

*************************************************************************
This is from the service bulletin that I received when I
bought my 1meg AGNUS. I have typed it in verbatum.


*************************************************************************
8372 FATTER AGNUS
INSTALLATION PROCEEDURES

The new 8372 Fatter Agnus IC, (P/N 318069-02), will require the
following modifications for proper operation.

If no modifications are performed the IC will address only 512K
of Chip RAM and operate only in the NTSC Mode.

NOTE: The correct IC Extractor tool must be used when removing 
the original 8370 FAT AGNUS from the socket. The Extractor Tool
is available from Commodore Parts. P/N 314874-01


INSTALLING THE FATTER AGNUS IN THE AMIGA 500

1) Locate Jumper Pad JP2 (Between 68000 at U1 and ROM at U6)
   and use a sharp Exacto Knife to cut the trace connecting
   the Bottom and Center Pads. Solder the Top and Center Pads.
   * This will enable Address 19 from the 68000.
    * See page 39 of A500 Service Manual
2) Locate the RAM Expansion Bus Connector CNX. Pins 1 and 2
   are on the Bottom Row and Pins 55 and 56 on the Top Row.
   Count up from the bottom, (By Twos), and locate Pins 41 and
   42. About 1/8" to the left is a plated hole with a trace
   which runs straight up, (Parallel with the white silkscreen 
   line designating the CNX Connector Outline.) This trace
   should connect between to Pin 32 of CNX and Pin 32 of the
   GARY IC U5. This trace must be cut.
   * This controls the _EXRAM Signal.
    * See Pages 39 and 40 of A500 Service Manual

   NOTE: There is also another trace running straight up next
         to the trace which must be cut. This trace may be 
         obscured by the silkscreen line.
         BE VERY CAREFUL THIS TRACE IS NOT CUT

3) Line Pin 1 of the 8372 FATTER AGNUS with Pin 1 of the 
   Socket and insert IC.


        INSTALLING FATTER AGNUS IN THE AMIGA 2000

1) Locate Jumper J101 (Lower Right of power Connector CN400.
   and move the installed Shorting Block to the left,
   Shorting Pins 2 and 3.
   * This will enable Address 19 from the 68000.
     * See Page 13 of A2000 System Schematics
2) Locate Jumper Pad J500 (Lower Left of 8520 IC at U301)
   and use a sharp Exacto Knife to cut the trace connecting
   the Two (2) Pads.
   * This controls the _EXRAM Signal.
     * See Page 9 of A2000 System Schematics
3) Line Pin 1 of the 8372 FATTER AGNUS with Pin 1 of the
   Socket and insert IC.

**********************************************************************



Tim Leonard.