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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: DoogUK on February 21, 2008, 10:55:20 PM
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Ok no doubt this has been asked before...but here goes.
In my A2000, i have an a2630 accelerator with 4mb ram onboard and a GVP series hd+8 with 4mb onboard.
I know the zorro bus will only address 8mb max...but is there any way i can add the extra 4mb to the GVP and make it useable?
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IIRC, there is a board by DKB that piggy-backs onto the 2630 and allows 112Megs of 32-bit fast ram. Beats the crap out if the 8 Meg/16-bit limit.
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It'd be much simpler to just put all the ram on one card, however it should be as easy as enabling the ram on the gvp.
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Nope there is no way around the 8 MB limit. Either you switch off the A2630 Ram (not recommendet) or you limit the Ram on the GVP to 4 MB.
The two existing A2630 Ram expansions DKB 2632 and Access32 are a way to have more Ram with a humble A2630 but usually prices for those boards are so high (as they are collectables) that it is cheaper to get an other accelerator alltogether like a Blizzard 2040 that allows for more Ram on the board itself.
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If you want to design your own ram expansion, this might help
http://www.thule.no/haynie/cpumods/a2630/dtrbd/readme.txt
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Lemmink is right, the only way is to add 32-bit memory via the 2630's RAM expansion connector. There's no way, other than possibly a major overhaul of several chips on the A2630, to remap the 2630 memory above the ZII address space. The good news is that the 2630 memory is 32-bit but as Dave Haynie explained, back in the day 8MB was considered a lot of memory and for compatibility with the original 68000 (fallback mode), placing the 4MB in the ZII space allowed use of the memory with the original cpu for compatibility. He made provision for extra 32-bit RAM via the access connector on the back of the card. But there is no simple way to change this arrangement.
On the other hand, Dave H has said would be possible to remap the 4MB of 32-bit memory space on the A2620 board, as the signal for doing so is apparently unused on the PAL chip involved. It would require a PAL replacement and a relatively simple modification using the aforementioned unused signal. Under this scenario you'd then have 8MB ZII memory available and 4MB of 32-bit memory on the A2620 above the ZII address space; so a total of 12MB. On the A2630, the unused address signal line was used for something else; probably has to do with the logic to make the A2630 asynchronous with the A2000 m/b.
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I wish i had the skills to build an expansion myself..i know the fast ram exansions for these accelerators are rare and command huge sums of money.
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I think I bought my DKB 2632 (in my hand right now) on eBay for a song just a few months ago. Maybe it slipped under everyone else's radar. It did come completely unpopulated, thats why I have not installed it yet. I haven't tried to find ram for it yet.
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One thing to keep in mind--when doing this, adding RAM especially via the A2632, you will have horrible SCSI performance and problems. Best thing to do is get a proper accelerator with SCSI built in. This way you will have good SCSI speed. With a SCSI controller you have the 16-bit to 32-bit DMA problem, and it really sucks let me tell you! (~200kb/s)
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@Tjlazer
I would agree using the A2632 rules out using the A2091 controller for the most part (unless you use some third party software hacks), but using a GVP HD+8 controller seems to work fine for me anyway. The GVP uses it's own special 24-bit dma software scheme so it differs from the A2091 performance wise.
You could always also use a non-dma scsi card like the Trumpcard, ICD or Dataflyer. The Trumpcard is the fastest afaik non-dma scsi controller out there.
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@Tjlazer
I would agree using the A2632 rules out using the A2091 controller for the most part (unless you use some third party software hacks), but using a GVP HD+8 controller seems to work fine for me anyway. The GVP uses it's own special 24-bit dma software scheme so it differs from the A2091 performance wise.
You could always also use a non-dma scsi card like the Trumpcard, ICD or Dataflyer. The Trumpcard is the fastest afaik non-dma scsi controller out there.
Necrobump.
I just was playing with my A2000 the last few days! It has a A2630 with 2MB on it and I was playing with my 2632 card and installed 32MB on it. Could not get any spare SCSI HDs working (all dead) so I threw in my DataFlyer Plus IDE. Works great! 2.5MB/s transfer speeds. Using an old 2GB IDE HD and it works awesome! ;)
I knew that back in 2008 had major issues with my A2091 HD. Did not play well with the 32-bit RAM.
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One thing to keep in mind--when doing this, adding RAM especially via the A2632, you will have horrible SCSI performance and problems.
Have you tried masking the buffer so that only 16 bit RAM is used for buffering?
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Yep tried that and it didn't help much. It was way under 1Mb/s. had to have 2MB fast RAM or it would crawl.
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While the DKB 2632 board might be hard to come by, mine takes regular 72-pin ram like that used on my CSPPC board and can be fully populated; this does lead to a lack of address space and for certain ZII boards I've had to lower the amount installed. The A2630 board is a stubborn bugger which does not allow any changes.
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Hello this is the first time here. But i also have an Amiga 2000 with a2630 cpu and 9 mb ram in total. have i understood it right, that i can not add more ram to it as it is now, without an upgrade?
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One thing to keep in mind--when doing this, adding RAM especially via the A2632, you will have horrible SCSI performance and problems. Best thing to do is get a proper accelerator with SCSI built in. This way you will have good SCSI speed. With a SCSI controller you have the 16-bit to 32-bit DMA problem, and it really sucks let me tell you! (~200kb/s)
Apparently, you never tried vbak2091 (Aminet) or Ralph Babel's Guru ROM.
Hint: Buffered DMA is much faster than PIO on the A2091!
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I'll second the Recommendation for Ralph Babel's Guru ROM, it significantly increased the performance of the A2091 Controller in my A4000.
It's too bad the Guru ROMs are no longer produced.
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The Commodore Amiga 2000 computer is best when used as a "classic" Amiga system. Then 2 megs chip and 8 megs fast is plenty of memory.
Why do you need more memory then this? Is it for ego or do you need more memory because of something you are trying to do.
It has been my experiance that the A2620 is actually a better processor board then the A2630, because, you maintain a lot of software compatibility that you lose with the 030 chip, and the board is made better.
I have often suggested that a person have two Amiga computers, an Amiga 2000 for all the classic software, and an Amiga 3000 or 4000 for the more modern stuff. One Amiga computer can NOT do it all. And when you try to force one to, that is when you run into problems.
My advice to you: Remove the A2630 board and downgrade to the A2620 board. Replace the GVP crap with a Commodore A2091 SCSI controller with 2 meg of ram. 1 meg chip and 6 megs fast ram is plenty of memory for doing classic Amiga stuff. Then get yourself an Amiga 3000 or 4000 computer for your more modern Amiga stuff.
About the A2091 SCSI controller, I recommend this board for all classic Amiga 2000 systems. It works, and it works very well. You must have at least the 6.6 roms, but, the 7.0 roms are best and correct many problems. Also, upgrade the SCSI chip to rev 08. The A2091 prefers hard drives that are LESS then 1 gb, even with the 7.0 roms and rev 08 WD chip. You MUST have the 2 megs of memory installed on the A2091 board. It is used as a buffer for the hard drive, as well as for fast ram. If the ram is not installed, all SCSI drive access will be much slower. Lets face it, 500 mb or 730 mb is more then enough hard drive space for a classic Amiga 2000, especially if you use SCSI ZIP and CD Rom drives.
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Hello this is the first time here. But i also have an Amiga 2000 with a2630 cpu and 9 mb ram in total. have i understood it right, that i can not add more ram to it as it is now, without an upgrade?
Yes that is correct. They only way to add memory is with a DKB 2632 RAM card. I have one. It attaches on the A2630 card and has four 72 pin SIMM slots for up to 112MB RAM (32MB, 32MB, 32MB, 16MB)
The only other way is for you to get a whole different CPU card that has SIMM slots on it. Some have 72 PIN SIMMs as well for up to 128MB max RAM.
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@nscaleworld
Don't think downgrading to an A2620 is an option nor does it make much sense. Software compatibility differences between an '020 and an '030 with data cache turned off are extremely marginal.
As a microarchitecture, the 68030 is basically a 68020 core with an additional data cache and a process shrink.
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I enjoyed my A2000 with '040 accelerator board, 32MB fast RAM, 4GB HD, Picasso II RTG board, HydraNet ethernet board and OS 3.9.
An all-in-one GVP '030 accelerator with SCSI is a good option though, if you can find one. The 8MB Zorro II limit is even more of a pain if you decide to add, say, an RTG board with 2MB of RAM because that eats into the limit.
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Yes that is correct. They only way to add memory is with a DKB 2632 RAM card. I have one. It attaches on the A2630 card and has four 72 pin SIMM slots for up to 112MB RAM (32MB, 32MB, 32MB, 16MB)
The only other way is for you to get a whole different CPU card that has SIMM slots on it. Some have 72 PIN SIMMs as well for up to 128MB max RAM.
okay thanks for your answer :-) but i must say, it is quite fast as it is now, i also have a amiga 2000 with stock cpu and 5 mb ram. that machine is quite slow compared to this one
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The way around this problem on an A2000 is to get another accelerator that will allow adding more RAM, or try to find a DKB 2632 card for the 2630.
It will very likely be easier, and cheaper to find another accelerator. I haven't seen a 2632 on the market in years!
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I would part with my A2630 & DKB2632 w/ 128Mb ram if someone really wanted it
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Apparently, you never tried vbak2091 (Aminet) or Ralph Babel's Guru ROM.
Hint: Buffered DMA is much faster than PIO on the A2091!
I did try these and other DMA hack tools for this issue and they did not work for me. I spent weeks trying and I just gave up. I recently tried again (WITHOUT the 2091) and it works great! (using IDE) LOL
http://www.amiga.org/forums/showthread.php?t=20008
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I get somewhat slow SCSI speed in my A2500 with a 2630/2632 and GVP 4008 combination but after hooking up a narrow SCSI chain to the CSPPC SCSI in my A4000, I realized that there was a termination issue in the SCSI chain in my A2500. I have a terminated CDRW on one end and a terminated external Jaz drive at the other with the unterminated internal HD in the middle. The SCSI controller is also terminated which is a problem and I only get around 1.3 MB/S max which is about half of what the card should give me. I haven't done it but the fix looks to me like either removing the terminating resitors in the GVP 4008 or reconfiguring the chain with the external connector on the GVP card not used and the termination on the CDRW removed and a SCSI external connector attached the next connector of the internal ribbon cable which will attach to the external Jaz drive. That should give me a proper SCSI chain with both ends terminated.
Oh, and I didn't pay a fantastic amount for my 2632. They are rare but maybe not in such high demand.
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I did try these and other DMA hack tools for this issue and they did not work for me. I spent weeks trying and I just gave up. I recently tried again (WITHOUT the 2091) and it works great! (using IDE) LOL
http://www.amiga.org/forums/showthread.php?t=20008
Either you did not install or configure the DMA hacks correctly (i.e. scsi.device, unit no., buffer size) or you maybe tried them on Kickstart 1.3 which most don't support.
Setting the mask is just a filesystem kludge to force PIO mode for "Brain Dead" SCSI drivers.
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I would part with my A2630 & DKB2632 w/ 128Mb ram if someone really wanted it
How much do you take for that :-)