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Author Topic: What A2000 MoBo can have 1MB chip RAM ?  (Read 6014 times)

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What A2000 MoBo can have 1MB chip RAM ?
« on: February 21, 2007, 09:03:03 AM »
Hello,
I have a nice 2000 here with a GVP G-Force 030 combo in it.

However, it has only 512k of chip ram. I know there is 1MB on the MoBo and I have a couple of 8372B chips but I don't know if the board can take it.

In the corner it says 312723 REV 4.4 but there is a white sticker on top that says 8485 REV 4.5.

I also have a couple of 8375 but I have no clue what version of Agnus there actually are.

Could anyone tell me if my MoBo will take the upgraded Agnus and also what other version of the 2000 MoBo will or won't take it ?

Thank you.
 

Offline melange

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Re: What A2000 MoBo can have 1MB chip RAM ?
« Reply #1 on: February 22, 2007, 06:26:13 AM »
You have the German 4 Layer Mobo I think.  There is probably a Jumper that you can set to change from 512K to 1MB Chip.  You must have an 8372A Agnus in there at least.  You could use the 8372B (I think) but you would still only be able to address 1MB of chip.
You would need to find a Mega-CHIP or TOP-CHIP 2MB Chip upgrade, (Just sits in the agnus socket).  Those are hard to come by.  I just paid an arm and a leg for one.  You should certainly get the 1MB Chip going though.  It's odd because both my A2000's were 1MB chip as standard.  Must be the German Mobo.  There are documents on the net that will explain the Jumpers for you.  Just do some googling.

If you have an 8371 Agnus, then replace it with an 8372A at least, or you cannot go to 1MB Chip.

Oh and if your going to remove the Agnus, make sure you get a PLCC chip puller, or you WILL break the socket for sure.
Good luck  :-)
2 x A1200 Blizzard IV 030@50Mhz
1 x A3000D 030@25Mhz
1 x A2000 030@25Mhz
1 x A2000, 2 x A600
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Offline Zac67

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Re: What A2000 MoBo can have 1MB chip RAM ?
« Reply #2 on: February 22, 2007, 07:26:25 AM »
All but the very first A2000(A) mobos can run 1 MB chip. The old mobos are easily recognized by their DIP (long) Agnus, all newer ones have a PLCC (square) one.

As melange stated, you need an ECS Agnus (numbers vary) and to reset a jumper. AFAIK 8375 will work.
 

Offline Lokki

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Re: What A2000 MoBo can have 1MB chip RAM ?
« Reply #3 on: February 22, 2007, 10:41:04 AM »
Quote

Zac67 wrote:
As melange stated, you need an ECS Agnus (numbers vary) and to reset a jumper. AFAIK 8375 will work.


8375 isn't pin compatible so don't just plug one in and try it!
\\"...Never stand next to someone who is throwing [crap] at an armed man...\\"
 

Offline melange

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Re: What A2000 MoBo can have 1MB chip RAM ?
« Reply #4 on: February 22, 2007, 11:20:30 AM »
I wasn't sure of that, but what I do know is that I have an A500 with a 2MB Chip board called an AX-RAM 4.  It has an 8372B Agnus and an acompanying Gary daughter Board with programmed chips (PAL) to make it all work.

  I also have a TOP CHIP 2MB Chip expansion in one of my A2000's, it also has an 8372B and sits on a mini pcb board, that plugs into the Agnus socket (there is extra logic all around that pcb in the form of smd chips). The top chip also has a Gary daughterboard also containing extra logic.  It dosen't seem to be that straight forward.  Think there is probably a bit of work in that hack whichever way you go about it.
2 x A1200 Blizzard IV 030@50Mhz
1 x A3000D 030@25Mhz
1 x A2000 030@25Mhz
1 x A2000, 2 x A600
2 x A500
 

Offline Lokki

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Re: What A2000 MoBo can have 1MB chip RAM ?
« Reply #5 on: February 22, 2007, 02:49:48 PM »
I can't spot my schematic with 8372B just at the minute but I'm pretty sure they're not a straightforward swap either, especially not if the A2000 is running OCS...
\\"...Never stand next to someone who is throwing [crap] at an armed man...\\"
 

Offline rkauer

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Re: What A2000 MoBo can have 1MB chip RAM ?
« Reply #6 on: February 22, 2007, 05:27:25 PM »
Sorry, fellows.

Just put the 8372 (A if NTSC or B if PAL) in the socket to be able to deal with 1 Mb ChipRAM. Oh, and that damm strap (J500, I think)must be closed.

Need a very hard hacking to give the 2000 hability to manage 2 Mb Chip (8375 Agnus, modified Gary, some ttl hacks, etc)
Goodbye people.

I\'ll pop on from time to time, RL is acting up.
 

Offline melange

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Re: What A2000 MoBo can have 1MB chip RAM ?
« Reply #7 on: February 22, 2007, 06:27:50 PM »
sorry rkauer

8372A is PAL or NTSC (Depends on your machines default configuration, can be easily set to either with a wire/jumper) ECS 1 meg Agnus!

8372B is PAL or NTSC (Depends on your machines default configuration can be easily set to either with a wire/jumper) ECS 2 meg Agnus!

I know this because I have used both chips, and had a hard hack using a switch between the PAL/NTSC pin on the Agnus and Earth.

This would allow me to change to NTSC for some games and get a smoother 60hz play.  I preferred to powerdown when switching over, but I think it was considered safe to do it on the fly.

2 x A1200 Blizzard IV 030@50Mhz
1 x A3000D 030@25Mhz
1 x A2000 030@25Mhz
1 x A2000, 2 x A600
2 x A500
 

Offline Zac67

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Re: What A2000 MoBo can have 1MB chip RAM ?
« Reply #8 on: February 22, 2007, 07:52:06 PM »
I very clearly remember getting 8375 as 'ECS 1 MB Agnus' directly from C= - stating that 'this is the follow up model'.

Unfortunately the model numbers are not that straight forward.  There have been several, serious attempts to build a table, please use the search function.

PS: Here's alexh's thread from last year - very good info: http://www.amiga.org/forums/showthread.php?t=20895
 

Offline Lokki

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Re: What A2000 MoBo can have 1MB chip RAM ?
« Reply #9 on: February 23, 2007, 11:13:53 AM »
I read those posts a while before I started posting myself, when I was still collecting schematic diagrams.

A more useful source of information for those wanting to do some serious hardware hacking would be a pinout table.
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Offline Lokki

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Re: What A2000 MoBo can have 1MB chip RAM ?
« Reply #10 on: February 23, 2007, 01:38:50 PM »
Quote

melange wrote:
8372B is PAL or NTSC (Depends on your machines default configuration can be easily set to either with a wire/jumper) ECS 2 meg Agnus!


I just found my other schematics and it looks like putting an 8372B into an A500 rev6 or higher is just a matter of cutting and jumping points at JP5. A20 replaces the XCLK signal from the Agnus so you're just jumping pin 35 to A20 and then giving XCLK an alternate source. I'd imagine the higher revision A2000s would have a similar point to JP5.
My bad!
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Offline melange

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Re: What A2000 MoBo can have 1MB chip RAM ?
« Reply #11 on: February 23, 2007, 06:55:47 PM »
Yep, that sounds about right.  In the A500 Rev 5, the same hack can be applied, but tracks need to be cut and wire links soldered in.
My first A500 was Rev5 which I had my 4MB AX-RAM card in.  It had tracks cut and links soldered in.

When I got a Rev6 Board, I only had to cut jumping points and join jumping points which was easy.
2 x A1200 Blizzard IV 030@50Mhz
1 x A3000D 030@25Mhz
1 x A2000 030@25Mhz
1 x A2000, 2 x A600
2 x A500
 

Offline rkauer

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Re: What A2000 MoBo can have 1MB chip RAM ?
« Reply #12 on: February 23, 2007, 07:35:08 PM »
Yeah, for A500 that is true. Note this: we talking about A2000, who comes with straps instead!

It's just a matter of close J500 and change the Fat Lady (Fat Agnus on low-end Amigas)...

Goodbye people.

I\'ll pop on from time to time, RL is acting up.
 

Offline rkauer

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Re: What A2000 MoBo can have 1MB chip RAM ?
« Reply #13 on: February 23, 2007, 07:39:39 PM »
And a FINAL information: ANY Agnus 8372 are able to manage 1 Mb ChipRAM...

Goodbye people.

I\'ll pop on from time to time, RL is acting up.
 

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Re: What A2000 MoBo can have 1MB chip RAM ?
« Reply #14 on: February 26, 2007, 01:39:44 AM »
I just put an 8372A in my good old 2000 and it still works fine but AVAIL says I still have 512k of chip ram...

If there is a jumper to switch around, now is the time to tell me which one it is.

Remember I have MoBo ver 4.4/4.5.

Thank you all!