Hi there, I recently got my hands on an A2630 with 4mb.. I just wanted to be clear that my intent was to use this with a SCSI controller card + HDD + zip / cdroms and I know sometimes accelerators like the TF series have trouble with DMA... making SCSI slow at best, if not impossible to work. I just wanted to be sure before I invest in this 112mb card that it wouldn't create some issues with DMA cards.
Will the big ram upgrade create any DMA trouble with SCSI cards?
- part12studios
- Thread is Unresolved
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Don't Panic. Please wash hands.
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If you have an A2091 or GVP controller (which both use DMA), you should expand them with a GuruROM before using memory in the 32-bit area.
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If you have a GVP Series II SCSI card, the FastROM (gvpscsi.device) v3.12 and the later 4.x series driver also has the built-in code to support CPU copy-up through Z2 24-bit DMA-flagged system RAM buffer. This is just like GuruROM v6 handles it, and GuruROM is gvpscsi's later cousin.
Set the DMA mask in mountlists/DOSDrivers or partition boot blocks for the above to it's full value 0xFFFFFFFE, and the driver does all the transfer work. If the mask is lower (Hint: HDToolBox defaults to lower value as a fail-safe), the filesystem tries to do the work, and intervenes before the driver sees the data buffer address to pick up or drop off at, and everything runs much slower. If you have OS 3.1.4 or 3.2, this detail is covered in the provided FAQs (I wrote them).
In all cases, it's best to have SOME AutoConfig Z2 FastRAM memory that supports DMA (located in $0020.0000-009F.FFFF) in the system. Your A2630 base 4MB AutoConfig memory suits this need well.
Performance is limited to about 1/2 of the Z2 bus speeds, with the CPU's performance to it's 32-bit RAM, and the device and SCSI bus performance additional +/- factors.
Disclaimer: I also build the GuruROMs.
For an A2091, you want a GuruROM. -
I just purchased the A2630 with Bigram 112MB. I have an A2091 with SCSI2SD installed on my A2000. Both cards are installed however the 112MB ram is not detected via sysinfo. It displays 0 bytes under the memory section. Related to this thread, do I need a GuruRom for the A2091 to have the 32bit 112MB ram of the BigRAM detected? Where can I purchase the GuruRom? Thanks
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Sysinfo will not show the size properly. Just look at the top of your WB screen or go to a shell and type "avail". It's a shortcoming of Sysinfo, not the RAM expansion.
do I need a GuruRom for the A2091 to have the 32bit 112MB ram of the BigRAM detected?
Not to have the RAM detected, but to be able to use it without major slowdowns or crashes. The memory on the expansion is not available through the DMA channel that the A2091 uses, and the original ROMs of the SCSI controller are not aware of that.
Where can I purchase the GuruRom?
I believe thebajaguy can either tell you where, or he has them for sale. It's a community thing if I remember right. To my knowledge, there is no reseller who is currently offering them.
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Thank you for the quick response. I only mentioned the sysinfo because the seller had sent a sysinfo screen shot displaying 112 mb. Although im sure i would have tried to verify everything was detected via sysinfo anyway. Thank you for your answer, I will ignore sysinfo and rely on your suggestion.
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My current interest sale thread for the GuruROM is on Aminet. I have a partial batch built (~40), and the parts to build more to match the current request list are on hand. I hope to have them ready this spring to address the currently interest group.
In the meantime, the slow, but still useful for filesystem operations mask of 0x00FFFFFE on each partition will have to do for now. With GuruROM, that mask gets opened up to 0x7FFFFFFE (or any value which includes the related upper address lines of the memory mapped >16MB).A side note that a Filesystem mask does not solve non-FFS activities where controller board DMA could occur. i.e. - Other filesystems using the SCSI interface must also be programmed for it - individually. Also, anything that doesn't use a filesystem must manually address it somehow internally - SCSI scanners, SCSI Tape backup tools, etc. (hence - my stance that the DMA Mask is a hack - the driver should always handle it - and never shall a DMA Mask ever be needed again).
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Display MoreSysinfo will not show the size properly. Just look at the top of your WB screen or go to a shell and type "avail". It's a shortcoming of Sysinfo, not the RAM expansion.
Not to have the RAM detected, but to be able to use it without major slowdowns or crashes. The memory on the expansion is not available through the DMA channel that the A2091 uses, and the original ROMs of the SCSI controller are not aware of that.
I believe thebajaguy can either tell you where, or he has them for sale. It's a community thing if I remember right. To my knowledge, there is no reseller who is currently offering them.
I just realized I have Sysinfo v3.24. The seller displayed 112mb from Sysinfo v4.00. As you suggested my Sysinfo version cannot read that memory but i suppose its possible with the latest version of Sysinfo. I did as you suggested and using 'avail' in shell. All is good Thanks!
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My current interest sale thread for the GuruROM is on Aminet. I have a partial batch built (~40), and the parts to build more to match the current request list are on hand. I hope to have them ready this spring to address the currently interest group.
Correction - Amibay (not Aminet)
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Almost all other cards are CPU-driven, and will theoretically top-off in the 1-2MB/sec range, with the device more likely to be the primary limiter in the equation. If the device's raw performance is natively <1.0MB/sec, it probably won't matter too much what card you use (sans the A2091's limitations without a GuruROM).
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If you want speed, then you should not put any RAM on the SCSI cards. These SCSI cards are in Z2 slots, which are way slower than the RAM on the accelerator. You will not lose any functionality if you don't have RAM there. The minimum required amount of RAM for the Guru ROM to transfer data through is on the 2630.
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OK good to know about that! I do want speed obviously
So it's a good thing that 2091 is empty. Here I was wondering if I needed to go buy some cmos chips.And as you said I'm going to need to jumper down the ram from 4mb to 2mb.. i'm not sure what it's currently jumpered too as the system it came from had multiple ram sources.
That said, which of these SCSI cards would you say is better to go with? I've always liked GVP stuff and since ram is not a concern I can remove those ram chips.. however as things get older, i'm looking at things that have a stronger presence in today's world where parts / replacements / knowledge is most available..
Also, was the bigram upgrade slot always intended for more ram? it's an interesting placement of the pins and just wondered if anything was ever made back in the day that used this slot? Or did you all engineer this slot to be used in a way it was never intended to be used for? we certainly know in 1989.. 112mb of ram was pretty insane..
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And as you said I'm going to need to jumper down the ram from 4mb to 2mb.. i'm not sure what it's currently jumpered too as the system it came from had multiple ram sources.
Just to be clear: Jumpering won't do the trick. The additional 2MB of chips need to be physically removed in order not to have an impact on data bus capacitance.
That said, which of these SCSI cards would you say is better to go with?
GVP and A2091 are both solid controllers. No preference on my side.
Also, was the bigram upgrade slot always intended for more ram?
Yes, there is not much else you can do with the collection of signals on that port.
we certainly know in 1989.. 112mb of ram was pretty insane..
It didn't take long for some companies to come up with 4-SIMM expansions. While it was insanely expensive, you could theoretically put in four 32-MByte modules into those. None of them had any auto-configuration; they all needed the "addmem" command in the startup-sequence. So that's the part where iComp has developed a "first" for the 2630.
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Display More
OK so I did a quick scan.. I have:
- 1x Commodore A2091 no ram in it. all 16 (what are those chips called?) chip sockets seem to be empty.
- 2x GVP Rev 5 HC+8 (both have a little ram in them. not maxed out.
So it what is this GuruROM you speak of thebajaguy? I would be interested in this for at least one of them. I don't know which one I want to keep for my A2630.. they all work. I'm leaning towards the A2091 because it's more common but also because I know GVP ram is tough to come by and i'm also not sure if it even matters since I'm using the bigram.. does any ram need to be on the boards to work well? I'm a bit confused about that.. as I know 8mb was the general system limit and on board accelerators allow that to be bypassed because the ram is on the board with the cpu..
Obviously I'd like performance, but I don't mind if it's not top performance.. amiga tends to load everything into ram anyway so HDD access (in my limited experience) seems mostly regarding loading the application.. loading files.. saving files.. once those actions are done.. it's all ram.. like rendering.. and working in the software doing the fun/creative stuff.
Jens is correct to not bother with adding RAM on the HC8 (or the A2091) - it will be slower memory in your system configuration (with the A2630 AutoConfig 32-bit RAM and the BigRAM), and won't help with I/O performance.
Using the GVP HC8, a FastROM driver of v3.12+ or 4.x on the card will know to buffer and CPU copy-up using the DMA-capable RAM on the A2630 - you will want some RAM on the A2630, be it 2MB or 4MB. Jens' guidance is certainly best here.
Next - Just like the GuruROM setup, set your filesystem partition values for DMA Mask with that card/driver to 0x7FFFFFFE and make sure the MaxTransfer is set to 0xFFFFFFFF. The gvpscsi driver will then interpret any transfer to/from an address on the BigRAM address space (>16MB Address line) as needing to be buffered, and will handle it automatically. If the mask value is smaller (0x00FFFFFF - a typical HDToolBox default on the Advanced page), it will hide the source/destination address from the driver. The filesystem will then try to do the buffering in much smaller pieces, and it's highly inefficient. You would have to use the smaller DMA mask with the A2091 until a GuruROM could be used.
As far as reliability, I agree with Jens - both cards have been solid in today's aging equipment spaces. My lean toward the GVP HC8 is purely based on the lower number of both parts and which are socketed. Pin contacts can oxidize from natural exposure/dissimilar metal contact. PGA sockets can weaken from heating and cooling cycles and the heavy pressure the inserted chips exert.
Aside from my past employ at GVP possibly exposing some bias, I can tell you that the same engineer designed both cards. I know that they used different approaches to the custom chip's featuring (DMAC vs DPRC), though.BTW - the GVP Series II cards (the HC8/HC+8) for the A2000's Zorro II slots use pairs of common > 1MBx8 30-pin SIMMs <. They do not use GVP custom SIMMs. The custom 64-pin GVP SIMM32s are used on the GVP accelerators (RAM32, Combo/G-Force).
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ok cool about 2091.. ready you loud and clear.. will hold and not modify
I will find out what FastROM I have (i assume it's something on the card i can see?) regarding both GVP boards
Gotcha about the A2630 ram.. does it matter how much ram needs to be on the GVP (thanks for clarifying this isn't the unobtanium based GVP ram simms.. this made me very leery about choosing them.. except they at least had ram already on them, but not fully loaded..
ok this DMA Mask / value stuff is outside of my current skill level so i'm not following it (yet) but I will certainly want to follow your advise I just might need some hand holding to insure i do things right!
I think I'm going to follow your points about fewer parts / more reliability. I may also end up not having to part with either of the GVP cards as to have a backup.
Now regarding this GuruROM, what is it exactly and how would i obtain such a thing? is it an eprom chip I install in one of the SCSI cards? How does it work?
Very exciting to learn all this!
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For the FastROM (a marketing name...sigh), just have the card in with the J4 jumper enabled and a ROM in the socket (@ top edge). Once it boots (can even be from a Workbench floppy with no HD, just wait for the timeout), open a CLI/Newshell and type:
version gvpscsi.device
What comes back is your (ROM) driver version. For your application, there is no difference between a v3.14-3.15 and the 4.x series - and all are compatible. Any changes were for later products and unrelated situations.
The DMA Mask and MaxTransfer are settings made in the HD prep tool used to partition the hard disk. I recommend using the tool you last used to prep the HD to make the modifications. I also recommend having any data on the target device you value backed up as human mistakes could render the filesystem inaccessible, and you may be reformatting and installing clean again. When the time comes, and you know the tool, we can walk thru the process. If you have a blank drive/media to work with, it may be helpful to tinker with that, without your data at risk.
GuruROM v6 is a ROM on an adapter PCB sized as a ROM. It's code is a more advanced cousin of the gvpscsi.device, and larger, yet by the same author. It's actually named omniscsi.device, and supports both the A2091 (DMAC-02) and the GVP Series II (DPRC) DMA chips on those products. Both boards are based on the 33C93A SCSI chip. The added feature in the driver (from the base of gvpscsi.device 4.15) is the support of Sync SCSI on the 33C93A -04 thru -08 chip. It requires 14MHz clocking of the 33C93A, which is the standard setting on most HC8 cards shipped with v3.14 or later FastROM. It requires a trace cut and jumper made on J201 of the A2091 to enable 14MHz clocking support, and a jumper added to one of the Options pins. It will run in 7MHz clock mode, but doesn't support Sync SCSI, and the overall SCSI bus performance potential is a bit less (no worse than C= 7.0 ROMs on a stock A2091).
Depending on what performance we get out of the GVP HC8 DMA transfers to the A2630 32-bit RAM with your SCSI device will be the deciding factor regarding the value of getting the GuruROM. If it's below a certain performance level, there's no value for it on the HC8 as gvpscsi.device supports the copy-up buffering anyway. It will help the A2091 with the A2630 BigRAM copy-up to BigRAM performance. Finally, the Sync SCSI boost isn't always supported by the disk devices being used, or it gains nothing due to the speed of the target SCSI device's media. In both HC8 and A2091 cases, the added performance of Sync speeds over Async is of no real value with the buffering activity to the high-mapped memory reducing the theoretical speeds possible by about 1/2.
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The SCSI2SD v5.x series will do about 1.25MB/sec on any of the controllers you have in a stock system, as it supports Async SCSI transfers only. . For that, stick with the existing driver. I think once you get a feel for the flash-based disk, you will notice it's faster than you remember disk being as there is no seek or spindle latency on that kind of device.
No problem on taking time to work things out. If you set up the SCSI2SD with multiple 'drives' with the provided tool (online download, program it off your modern PC), at multiple SCSI IDs, you can define each 'drive' as <4GB, then use the GVP FastPrep (or ExpertPrep) tool to further partition each disk into one more more actual partitions. Remember that OS 3.1 has disk capacity limits of <4GB and partition sizes <2GB.
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The last reply was more than 365 days ago, this thread is most likely obsolete. It is recommended to create a new thread instead.
