Conference hydra::amiga_v1

	Even though the Fatter Agnus is installed, Commodore, as yet, are not
	activating it. I think that later in the year, the A500 will be 
	marketed with 1M on board, and at that time, Commodore will activate
	the Agnus.

	I have recently installed a 4M Baseboard Expansion and the instructions
	for activating the Agnus are in the instructions somewhere. I will look
	them out tonight and post them here.

Regards
Bill

    Lets not forget warrenty issues here. You could use the logic that your
    warrenty has expired, so it don't matter. However if you cut,or solder
    etc: ,and then your amiga dies later you will not be able to get credit
    on a trade in for the mother board. I have developed the opinion that
    if one wants to do graphics work,and or video the 2000 is the lowest
    system that I could recommend,because of this chip ram problem. This
    is CBM's way of seperating the high end from the low, or at least it
    appears so.
    							bill 

	For those A500's which have a Rev 6 Mother board and a fatter AGNUS
	installed but not activated the jumper setting modifications to 
	activate the chip are as follows :

		JP-3 Jumper positions: leave at factory setting
			   	      i.e. 1-3 connected
					   2-4 connected.

		JP-2 Jumper positions: 1-2 connected
				       2-3 disconnected.

	The JP-2 jumper can be found just to the right of the 68000 cpu chip
	and just above the Kickstart chip located on the left side of the machine.

	WARNING: The above procedure WILL invalidate your warranty.

Regards
Bill

    Thanks for your answers folks but I have no problem activating the
    Fatter Agnus as such, the question is: rather than use the 501 for half
    of that 1 Meg chipram, can I pop 4 more ramchips onto the motherboard's
    empty ramchip sockets, alter the JP3 and now have ALL my chipram on the
    motherboard?
    
    If so, can I still use the 501 connector for slow-fast memory or will I
    no longer have access to it?
    
    cheers fjeff

	With the Fatter Agnus activated, you should have no problem inserting
	and using the extra 4 memory chips on the motherboard.

	However, some expansion memories inserted in the 501 slot are not as
	yet compatible with the extra 1/2 M added to the motherboard. 

	Baseboard is an example of this. To get the use of the extra 1/2M on
	the motherboard, you remove the chips from the motherboard and insert
	them on the expansion board. Here is what the instructions state:

		"The JP-3 jumper is used only if the Amiga has 1M installed on
		 the motherboard. This jumper must be set (ie disconnect 2 & 4),
		 to disconnect 512K of the memory on the motherboard and
		 replace it with 512K on the Baseboard. This will not affect
		 the amount of agnus chip memory; it will still be 1M but
		 some must come from the Baseboard. If the memory chips are 
		 socketed or can be removed, they can be used in the Baseboard."

	I know that this might not apply to you right now, but might be useful
	if you expand. At the moment, I am not sure if other expansion systems
	work the same way.

Regards
Bill 

    The answer to this has been kindly pointed out to me by Shaun Moran
    (thanks mate!).......TAPE::AMIGA:[000000.AMIGA.HARDWARE]RASCAL.DOC or
    it is also a  .LZH file in this directory.
    The solution/hack is provided by a fellow countryman from the same city
    as myself....Christchurch, New Zealand!..........kiwis everywhere!!
    
    cheers fjeff

fjeff,

So did you do RASCAL??

I need some reassurance from someone about how easy it was before I
fumble about inside my 1.2 year old Amy!!

Cheers,

Greg

    How do I know if I've got a fatter Agnus?
    
    I prised Amy open and I have a rev 6a motherboard (great line on their
    said B52 Rock Lobster - CBM code word?)
    
    If I've "got a fat one", what benefit is it to me, if I do what BIll
    instructed?
    
    
    Cheers,
    
    Greg

Just get to a CLI and type AVAIL. This will tell you how much CHIP and FAST
memory you have. If the total CHIP is more than 512K, you have the 1meg agnus.
If the total CHIP is more than 1meg, you have a 2meg agnus (but you would know 
that :-)

john

    Re .8/.9:
    
.8  How do I know if I have a 1meg Agnus?
    
.9  Just get to a CLI and type AVAIL. This will tell you how much CHIP and
.9  FAST memory you have. If the total CHIP is more than 512K, you have the
.9  1meg agnus. If the total CHIP is more than 1meg, you have a 2meg agnus
.9  (but you would know  that :-)
    
    It's not that simple.  Unless the jumpers have been moved, a stock
    A500 with a Rev 6 motherboard and the 1MB Fat Agnus will still show
    512KB of CHIP RAM.  There are a few programs around that will figure
    out the custom chip versions regardless of the jumper settings.
    
    Since .8 has already opened up his A500, he can do direct inspection of
    the chip's number, which has changed each time a newer version was
    produced.  I believe the original A1000 Fat Agnus ended in 0.  The
    512KB version used in A500s & A2000s until late 1989 ended in 1.  The
    1MB version used since then ends in 2.  All A500s built since 1990 are
    reputed to have the 1MB version even though the jumpers are still set
    to make the system see only 512KB of CHIP RAM.

    My MegaChip 2000 upgrade docs say that the chip number on the 1MB Agnus
    ends with A while the chip number on the 512K is just numbers.  If
    forget the exact numbers, but it was like 8370 was 512K and 8370A was
    1MB.  
    
    Terry
    

Re: .8

> I have a rev 6a motherboard (great line on their said B52 Rock Lobster
>- CBM code word?)

The code name for the Amiga 500 project was "Rock Lobster" after the
song by the group, The B-52s.

The code name was picked after someone working on the Amiga 500 project
said, "If Commodore can't sell this machine, they should send in the
B-52s [the bomber] and level this place."

Dave Haynie, the chief hardware guy on the Amiga 500, the Amiga 2000 model B,
the '20 and '30 accelerator cards, and the 3000 is very fond of rock lyrics.
If you get copies of the semantics for the machines from Commodore, all
of them have a quote from some rock song on them.
 

    re .12
    
    Thought so, One of my fav B52 songs!!
    
    
    Has anyone out there with a Rev 6 A500 enabled there Fatter Agnus! IF
    so which of GARY's legs did you have to alter!!
    
    Cheers,
    
    
    Greg

    OK, I re-opened AMy up and there it was 8372A, Fatter Agnus. Advertised
    over here in the UK for 60 to 70 pounds!. I have a few question about
    how to enable it.
    
    .4 (?) Say connect 1 and 2 and disconnect 2-3 on JP3. JP3 is made up of
    3 square blobs about a millimetre square. TO conect 1 and 2 I just drop
    some solder touching the two? 
    
    How about disconnecting 2-3? I assume I have to cut the connection, how
    do I do this? Th sharpest thing I have is a STANLY knife!
    
    
    Lastly will my plug in trapdoor expansion still work??
    
    
    
    Any help would be appreciated as I hope to get this going this weekend!
    
    
    
    
    Greg

    
     I haven`t opened up my Amy apart from inserting the 512k expansion
     what I want to know is where do I locate Agnus in the Amy and if it
     is a Fat Agnus if I enable it (presumming I can) will it shut out
     the expansion board ie. will I loose the 512K for a larger Agnus.
     If not I should have 1.5Meg Yes/no. I am totaly confused about Agnus
     I have my Amy about 2� years but I`m not familar with the hardware.
     Someone help me please 8*( 

    Re .15:                 -< Please in english >-
    
>   I haven`t opened up my Amy apart from inserting the 512k expansion
>   what I want to know is where do I locate Agnus in the Amy and if it
>   is a Fat Agnus if I enable it (presumming I can) will it shut out
>   the expansion board ie. will I loose the 512K for a larger Agnus.
>   If not I should have 1.5Meg Yes/no. I am totaly confused about Agnus
>   I have my Amy about 2� years but I`m not familar with the hardware.
>   Someone help me please 8*(
    
    I can see your confusion.  Let me try to help (without making things
    worse).  Let's start from the basics on A500 memory configuration.
    
    The 512KB that is mounted on the A500 mother board is CHIP RAM, which
    means it is visible to the custom chips (most notably "Fat Agnus") for
    audio and video output structures.
    
    Memory that is added on the expansion port (typically within an A590 or
    similar SCSI disk controller) is "Fast RAM".  It isn't shared between
    the custom chips and CPU, so the CPU can use it more effectively.
    
    The 512KB that is mounted in the A501 clock/memory expansion (or clone)
    board is often referred to as "half-fast RAM".  In a standard A500,
    AmigaDOS configures this memory as "fast" RAM even though it operates
    at the same speed as the built-in CHIP RAM.
    
    The standard (512KB) Fat Agnus can only use the first 512KB CHIP RAM. 
    The (1MB) "Fatter Agnus", when the address lines are properly enabled,
    sees the 512KB on the motherboard and the 512KB in the A501 as 1MB of
    CHIP RAM.  Once you've upgraded to 1MB of CHIP RAM the system WILL NOT
    BOOT if the A501 is removed or fails.  The increase in CHIP RAM is at
    the expense of "half-fast" RAM.  An A500 with an A501 and no other
    memory will show 1MB of CHIP RAM and NO [half-]fast RAM.  Some software
    packages will not operate in this configuration, so you should give
    serious thought about adding more memory somewhere.
    
    Opening an A500 requires a T-10 Torx screwdriver.  Actually, any small-
    bladed screwdriver will work, but could damage the screws.  For the
    last year or so, opening the A500 (other than the belly door) requires
    breaking a seal and voiding the manufacturer's warranty.  Making ANY
    modifications to the motherboard will render it unexchangeable, which
    means you'll have to buy a new one for several hundred dollars if the
    one you've modified dies.  STATIC ELECTRICITY WILL KILL YOUR A500 IF
    YOU'RE NOT CAREFUL.  TAKE PROPER PRECAUTIONS WHENEVER YOU OPEN IT.
    
    Those warnings aside, the motherboard is marked at one corner with its
    revision number.  (I have a Rev 5 board, where the mark is at the lower
    right hand corner, under the keyboard.)  Any model older than Rev 6
    will require you to cut one or more circuit etches in order to allow
    the Fatter Agnus to address beyond 512KB.  Circuit board layouts vary
    between versions, so you'll have to read the board next to each of the
    major chips to figure out who is located where (most have names, hence
    "who" instead of "what" 8^).  The Fat Agnus is a square chip, which
    means you should use an appropriate chip extractor to remove it
    without damaging either the chip or its socket.

    
    Thanks Bill,
               You`ve made it clearer, so now that I have my 512K exp.
    I can reset (as such) fat Agnus to become even Fatter. This is done 
    by (if need be) by cutting the traces.
                                          Woody (slightly confused)

      I have a rev 5 A500 with a fully loaded Baseboard. When I added
    the fatter Agnus. Most of my software would not load and the one's
    that loaded had serious graphic's problems. I went back over the 
    install and it all looked right according to the baseboard manual.
    So I reversed the entire install including the etch at jp2. And
    it works fine. Do I have a bad chip or am I missing something
    again.
    
    					Thanks Scott

    
    	Well I've finally upgraded my A500 to have 1 Meg CHIP...
    
    	I also have a rev 5 board and I changed JP2 to middle pad to top
    pad.
    
    	Rather that cut my mother board or leave out pin 32 of the GARY
    chip I cut the pin on the ram expansion...
    
    	I also had to do one extra part that the note's files forgot to
    talk about and that was that if you DON'T take PIN 41 of the AGNUS chip
    HIGH (+5V via a 4.7k resistor pref. I just pushed the pin to the body
    of the chip and pushed the socket pin in ) This makes the system BOOT
    into PAL .......!!!!
    
    	I've had no problems YET...
    
    	Steve Goldstein

Terry,

In .11 you say that you have a MegaChip 2000.  I swear i read more about
that somewhere - i don't know if it was by you.  However I can't find
anything else in the conference on it.

If you have already written something about your experiences with it, can
you point me to that.  If not, I would very much like to hear of your
experiences since I am interested in buying one:

- Where did you buy it?
- Any problems with reliability or software compatibility?
- What configuration are you running it in?
- Did you install it yourself?
  If yes, how were the instructions?

Inquiring minds want to know

	Paul

    Check out note number 4389, specifically .12 and .19 from me.  Most
    everything you ask is answered there.  I bought the chip mail order
    through the Grapevine group who advertises in most Amiga mags. I
    haven't found any incompatible software.  What the Grapevine people
    told me seems to be true, any software that works with 1MB chip ram
    works with 2MBs at well.  It's only the programs which break going from
    512K to 1MB which also break with 2MBs.
    
    Installation was a snap.  I'm a sales rep (read:non-technical) and I
    did it in aboutnb 20 minutes without a hitch. I'm very happy with it.
    
    Terry
    

Thanks,

I knew I had read that information, but I couldn't find it.  There are too
damn many notes in this conf to visually scan them all when looking for
something.  I searched back several hundred using various keys, but didn't
find that note.

	Paul