A2000 (2500) ram question

[melott]

I bought this A2500 on EBay and I'm doing some upgrading.
The machine has a 2091 HardCard and a 2630 accellerator.

On the HardCard I can install 2 megs ram, (none installed now)
and on the accellerator I can install 4 megs total.
The accellerator has 2 megs installed now.
I just bought a Supra ram expander which holds 8 megs.

The question is.. if I max out the HardCard, accelerator
and the ram expander will all the ram be seen (14 megs)
or will there be address conflicts between the cards.

From what I've read, there's a DKB card that plugs onto
the accellerator that allows 32 megs ram to be installed
although I suspect that card would be hard to find.
If anyone has a DKB 2632 card for sale I'm interested.

[spirantho]

I don't know much about the Supra RAM expander, but if it's not local to the accelerator I'd imagine it'd be Zorro II RAM - hence very slow! If it were just running a 68000 it'd be fine, but your '030 would never be able to get fast enough access over the Zorro II bus to get any decent speed, I imagine. Best bet is to get another 030 accelerator - I use an Apollo 2030 in my A1500 - which has SIMM slots. If your 030 is using Zorro II RAM you'll be lucky to get more than about A1200 (unexpanded) speeds despite the 030.

But then I could be wrong.

[Lemmink]

As all those cards put their RAM into the ZII adressspace you will get 8MB max. While adding more then 2MB to the supra in your setup will lead the machine to refuse to boot up, or simply ignore the card with the lowest priority.
Modern well designes Accelerator allocate their memmory outside if the ZII adresspace, better get one of those and you can install up to 128 MB (depending on the card).

There are two ways to add 32bit FAST-Ram (that is outside of ZII) to the A2630. One is the Access32 wich can hold max 32MB in form of today very expensive and hard to get ZIP-Chips

http://www.amiga-hardware.com/access32.html

And the other is the DKB2632 you mentioned the can be expanded to max. 112MB in form of cheap PS2 RAM like on all modern Amiga Turboboards

http://www.amiga-hardware.com/dkb2632.html

Both cards are quite rare and hard to get. And it won`t make sense to get one for the A2630 to actually use it, as collectors prices are paid for both boards.
A couple of day ago a DKB2632 went for over 100 EUR on german ebay (and the board was without RAM and handbook) you could easyly get a  Blizzard2040 for that amount of money and have a way better card.  

[Kronos]

On top of what Lemmink wrote:

I suspect that this is the same A2500 which has the A2286-card in it ?

The PC-card will allocate a full 2MB piece of address-space, while only needing 128KB of it. Problem is that the Zorro-IO-space won't allow more than 64K per card, and the RAM-space can only be allocated in 2MB-chunks.

So 6MB fast (4 on A2630, 2 on the SCSI) and 1MB chip (on the mobo) is as far as you will get.

Unless ofcourse you replace the A2630 with something more modern  :-P

[artman]

Congrats on a nice purchase, Mel.  My main Amiga is an A2000 and I wouldn't trade it for all the proverbeal tea.  Let me know if I can be of help.  Can't be too technical though.  Best regards...Art

[BoingBoss]

Hi melott,

You can only have a maximum of 8 megs of memory on the Zorro II bus.  The 32-bit memory on the A2630 is on the Zorro II bus, so that is 2 megs already (it is the first memory that the Amiga 2000 sees).  If you want faster SCSI hard disk access, then yes install the 2 megs onto the A2091 board.  You will need 16 - 44256 DRAMs.  So now that is 4 megs of memory on the Zorro II bus.  Remove the Bridgeboard (if there is one) and install only 2 megs onto the SupraRAM board.  You will need 16 - 1M X 1 DRAMs.  So now that is 6 megs of memory on the Zorro II bus.  A video board will use the remaining 2 megs of Zorro II bus space (a 1 or 2 meg board).  STAY AWAY from 4 meg video boards.  My advice:  Remove the A2091 and A2630 boards and install a GVP Combo Board or a Blizzard Combo board.     :-)