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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: on February 21, 2007, 09:03:03 AM
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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.
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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 :-)
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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.
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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!
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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.
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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...
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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)
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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.
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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
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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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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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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.
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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)...
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And a FINAL information: ANY Agnus 8372 are able to manage 1 Mb ChipRAM...
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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!
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This is taken from one of the miscellaneous docs I've been reading, not sure where it's from or who originally wrote it:
Find Jumper J101 located on the lower right side of the power connector CN400, and consists of 3 posts - 2 of the posts are shorted together using a shorting block. Remove the shorting block and move it to the left, towards the power connector. For further info, see Page 13 of the A2000 system schematics - this jumper will enable address line 19 from the 68000 which controls the 1 meg address range.
Locate and cut Jumper pad J500 (to the lower left of the 8520 at U301). This is a 2-pad jumper with a trace connecting the two pads. See Page 9 of the A2000 system schematics - cutting this trace keeps the _EXRAM signal from being tied to ground.
To enable PAL rather than NTSC - locate and cut J102, NOT J201 as suggested in some docs. This is the equivalent of bending pin 41 of Agnes in the A500 mod.
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Lokki wrote:
This is taken from one of the miscellaneous docs I've been reading, not sure where it's from or who originally wrote it:
Find Jumper J101 located on the lower right side of the power connector CN400, and consists of 3 posts - 2 of the posts are shorted together using a shorting block. Remove the shorting block and move it to the left, towards the power connector. For further info, see Page 13 of the A2000 system schematics - this jumper will enable address line 19 from the 68000 which controls the 1 meg address range.
Locate and cut Jumper pad J500 (to the lower left of the 8520 at U301). This is a 2-pad jumper with a trace connecting the two pads. See Page 9 of the A2000 system schematics - cutting this trace keeps the _EXRAM signal from being tied to ground.
To enable PAL rather than NTSC - locate and cut J102, NOT J201 as suggested in some docs. This is the equivalent of bending pin 41 of Agnes in the A500 mod.
Lokki you are a savior!
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J101 !?!?!?!?
Is not the J500 (RAM adress)) ?!?!?
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That's what the agnus substitution doc said... I'm not saying it's gospel, it's been too long since I saw inside an A2000. That and I can't find my A2000 schematics, I seem to have misplaced them.
It sounds about right though.
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Lokki wrote:
That's what the agnus substitution doc said... I'm not saying it's gospel, it's been too long since I saw inside an A2000. That and I can't find my A2000 schematics, I seem to have misplaced them.
It sounds about right though.
J101 and J500 did it! I have 1MB chip!
Thanx again Lokki!
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No worries mate, good to have confirmation of it too! :-)
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Lokki wrote:
This is taken from one of the miscellaneous docs I've been reading, not sure where it's from or who originally wrote it:
Find Jumper J101 located on the lower right side of the power connector CN400, and consists of 3 posts - 2 of the posts are shorted together using a shorting block. Remove the shorting block and move it to the left, towards the power connector. For further info, see Page 13 of the A2000 system schematics - this jumper will enable address line 19 from the 68000 which controls the 1 meg address range.
Locate and cut Jumper pad J500 (to the lower left of the 8520 at U301). This is a 2-pad jumper with a trace connecting the two pads. See Page 9 of the A2000 system schematics - cutting this trace keeps the _EXRAM signal from being tied to ground.
To enable PAL rather than NTSC - locate and cut J102, NOT J201 as suggested in some docs. This is the equivalent of bending pin 41 of Agnes in the A500 mod.
Just a small update on this old but quite useful post.
On the Rev 6.2 MoBos, the jumper J101 is vertical rather than horizontal on the board. To get 1MB of chip, you have to move the jumper to the higher position that is still towards connector CN400.
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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.
On the off chance any unlucky person has a revision A motherboard A2000, I have one of the 1MB RAM cards that go in the MMU slot (what looks like the CPU slot in real Amiga 2000s). This is of no use in later Amiga 2000s, and was sold to me by a vendor who didnt know that it was only useful in the crappy A2000s.
I'm prepared to give this to anyone in the US for free. I'll send it overseas too, for the cost of shipping.
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murple wrote:
... in the crappy A2000s.
I don't share your point of view concerning the A2000.
True enough the Zorro II slots aren't exactly top performance but this machine seems to be built around the legend concerning russian made combat helicopters...
This legend says "first they made bulldozers then they strapped a rotor to it..."
Just like these helicopeters, the A2000 is an incredibly rugged and long lasting workhorse. I like the incredibly tough casing and the totally overscaled power supply.
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I guess there is a little misunderstanding. The very first versions of the A2000 that were designed in germany are often refered to as well A2000 while the later revisions designed in the US are refered to B2000. The A one are more like a collectable today as there are a lot of compatibility issues plus you only can have 512k ChipRAM unless you put the mentioned card into the MMU-slot. So either 512k chip or no accelerator (thare is a lot of compatibility problems there too)
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From what I recall (haven't read the info in a while) the A2000 Rev. A is essentially just an A500 motherboard that some German engineers added some Zorro slots to. It may look like an Amiga 2000. It may say Amiga 2000 on the label. It isn't an Amiga 2000 though, but rather is the result of some German engineers who were idiots.
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Well, guess its more like a 1000 than 500. Quoth David Haynie:
Yes. The original A2000 was designed in Germany. It was based on an integration of the A1000 motherboard design and the example Zorro II backplane from "Schematics and Expansion Specifications", the A1000 hardware manual. It used the thin Agnus, which handled only 512K of DRAM. They added a "Genlock" slot, which was essentially just the 23-bit video signals on an internal connector, and the "MMU" slot, which was essentially just the A1000 external edge connector on an internal slot. The machine shipped with 512K of Fast RAM in this slot, though the case was slow and had some reliability problems. About 60,000 of these machines were made, so I've heard.
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Yes. Since the A2000 - or A2000A - officially: Rev 4.0 - was built based on the A1000 OCS, there's no way to expand it to 1 or even 2 MB chip - other than swapping the board with a later rev.
The A model was designed in Germany and was basically an A1000 plus the Zorro backplane base design. When the better Fat Agnus for the A500 was designed, the guys in West Chester designed a new & improved B2000 (Rev 4.1+) that also featured the Buster (the German A2000 had lots of discreet logic there).
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@Lemmink
I think you got some things wrong here.
The A2000A is pretty much an A1000+Z2-slots, so it allways has only 512K Chip, since thats the maximum the "thin" Agnus can handle.
The RAM in the MMU-Slot is REAL Fast-Mem, not just Slow-Mem as in the later A2000s.
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I might have a related problem. I have a early 2000B machine Rev 4.4. When I got it, it had Kickstart 1.2 in it and already had 1MB Chip enabled. Problem is when I try to do PAL screen goes black and video is jumpy. Switch back to NTSC and it works ok. So PAL does not work. What could cause this? It has a 8372 Agnus.
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Zac67 wrote:
Yes. Since the A2000 - or A2000A - officially: Rev 4.0 - was built based on the A1000 OCS, there's no way to expand it to 1 or even 2 MB chip - other than swapping the board with a later rev.
Well, there is this:
http://amigahardware.mariomisic.de/cgi-bin/showhardware_en.cgi?HARDID=967
That is what I have, it was sold to me by someone who didn't know it was only of use in the bogus 2000s (A2000 rev A). The page there says "This card may not be compatible with Model B & C A2000s" and I have seen info (from Haynie I think) that confirms it can NOT be used in a real 2000.
If anyone has an A2000A and wants the RAM expansion, I've got one. Its of no use to me.
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This is taken from one of the miscellaneous docs I've been reading, not sure where it's from or who originally wrote it:
Find Jumper J101 located on the lower right side of the power connector CN400, and consists of 3 posts - 2 of the posts are shorted together using a shorting block. Remove the shorting block and move it to the left, towards the power connector. For further info, see Page 13 of the A2000 system schematics - this jumper will enable address line 19 from the 68000 which controls the 1 meg address range.
Locate and cut Jumper pad J500 (to the lower left of the 8520 at U301). This is a 2-pad jumper with a trace connecting the two pads. See Page 9 of the A2000 system schematics - cutting this trace keeps the _EXRAM signal from being tied to ground.
To enable PAL rather than NTSC - locate and cut J102, NOT J201 as suggested in some docs. This is the equivalent of bending pin 41 of Agnes in the A500 mod.
Oooold thread bump because this worked for my A2000 rev 4 and now I can use WHDload :thumbup:
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Well, there is this:
http://amigahardware.mariomisic.de/cgi-bin/showhardware_en.cgi?HARDID=967
(old statement, but still)
No, there isn't. The Ranger mem card you pointed out is real $C00000 fast RAM and it's got nothing to do with chip RAM. Sorry.
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Taken from TBBOAH:
J101 This jumper determines the high order address bit for Fat Agnus. In it's normal position, the high-order bit is A23; in it's other position, this bit is A19. The current Fat Agnus chip requires the A23 signal for proper management of the memory at $C00000. Future Fat Agnus chips may do things differently; this keeps the current board compatible with simple enhancements.
J500 This jumper is used to enable the 512k of RAM at $C00000 and the real-time clock. It is normally closed; opening it will disable both this extra RAM and the real-time clock.
Whoops, looks like Lokki posted similar info. This thread is like an adventure through the Bermuda Triangle! lol
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Opening J500 will NOT disable the clock.
Even the SM states this (probably the source anyway), but deactivating _EXRAM will just remove the RAM at $C00000 and has nothing whatsoever to do with the RTC.
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I might have a related problem. I have a early 2000B machine Rev 4.4. When I got it, it had Kickstart 1.2 in it and already had 1MB Chip enabled. Problem is when I try to do PAL screen goes black and video is jumpy. Switch back to NTSC and it works ok. So PAL does not work. What could cause this? It has a 8372 Agnus.
Machine locked by the 1.2 ROM / Workbench. Upgrade the ROM & WB to 1.3.