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Conference hydra::amiga_v1

Title:AMIGA NOTES
Notice:Join us in the *NEW* conference - HYDRA::AMIGA_V2
Moderator:HYDRA::MOORE
Created:Sat Apr 26 1986
Last Modified:Wed Feb 05 1992
Last Successful Update:Fri Jun 06 1997
Number of topics:5378
Total number of notes:38326

986.0. "FAT AGNUS" by HIT::WHERRY (Servant of Cthulhu) Fri Dec 18 1987 16:21

    I just got my B2000 today.
    
    In the documentation supplied were some Amiga 2000 Manual Update
    Pages.
    
    On the second to the last page was a listing of how to set the
    internal jumpers.  ONE was for FAT AGNUS...
    
    The last page was title CUSTOM ANIMATION CHIP -- FAT AGNUS
    
    	This page described all the functions of the FAT AGNUS,
    and included a block diagram for FAT AGNUS.  Has anybody
    seen this?  Guess I am gonna have to open my machine up
    this evening and try and see if this thing is in there.
    The chip is labeled an 8370 on this page.  Does anybody know
    what the current AGNUS is labeled??
    
    brad
    
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986.1Check the Manual First!HIT::WHERRYServant of CthulhuFri Dec 18 1987 16:2513
    
    With regard to labeling of AGNUS, I looked in the Introduction to
    the Amiga 2000 which has yes, the Amiga 2000 schematics...nifty...
    Wish I knew what all those squiggly lines mean.  I managed to find
    the AGNUS chip in them.  It is labeled 8361.
    
    so, to you EE types, does this mean that If I open my machine up
    and find a chip labeled 8370 that there is a FAT AGNUS inside?
    
    boy, things can get really strange in a day can't they.
    
    brad
    
986.2BAGELS::BRANNONDave BrannonFri Dec 18 1987 16:476
    the FAT AGNUS in the B2000 is still only for 512K chip ram.
    The chip has the pins to support 1 Meg chip ram but it doesn't 
    use them.  A future upgrade will have a new FAT AGNUS chip that
    does use them.
    
    -dave
986.3ANGORA::SMCAFEESteve McAfeeFri Dec 18 1987 18:369
    
    There was a usenet message recently about a someone selling
    the 2000 with the machine already configured for FAT AGNUS.  Most
    likely they simply did whatever was mentioned on the page you
    discussed.  Unfortunately since the machines didn't actually have
    a FAT AGNUS, they would crash when chip memory allocations went
    over 512K.  Not surprising.
    
    - steve mcafee
986.4The Fat LadyTLE::RMEYERSRandy MeyersFri Dec 18 1987 21:419
Yep, all Amiga 500s and all B2000s come with the (limited to 512K chip
ram) Fat AGNUS.  The limited Fat AGNUS is also handling the 512K of
half-fast ram that is standard in the B2000 and an option in the A500.
When the true Fat AGNUS comes out it is expected that the 512K of half-fast
ram at C00000 will disappear and become chip memory located at 8000.

The chip is easy to find.  It is a large square chip in about the center
of the motherboard.  All the major chips on the board have their name
next to then on the circuit board.  The Fat AGNUS is labeled, "The Fat Lady."