For Sale GuruROM for GVP Series II and C= A2091/A590 + v6.16 omniscsi.device


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May 9, 2017
United States
Rhode Island
Support Thread: - please use this thread for technical questions/troubleshooting.

This listing is for a PRE-ORDER for the GuruROM based on the SpeedGeek adapter (which is only slightly larger than the EPROM itself), and the v6.16 GuruROM that requires the adapter. The actual GuruROM code size is too big for the address space the boards provide for ROM code, making the adapter necessary.
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Summary: I have secured the rights to produce the most recent adapter from SpeedGeek, and distribute with it the v6.16 omniscsi.device driver ROM code from Ralph Babel. This is the same adapter as last offered by SpeedGeek about a year or two ago. I will be the support point for them.

(Most of Group 1 is being addressed since 23-Mar-2019, with new interests are going into Group 2, with no announced availability on that group yet)

No money is being collected until an adapter is ready to ship. You may opt out of this pre-order at any time. You will be contacted via PM once it becomes available. The estimated cost will be $45-$50 US for the ROM+Adapter, and (hopefully) a similarly priced amount overseas from the EU, plus shipping and payment service fees. I am also in the process of rewriting the manual, which was a scanned and electronically distributed version from back @v6.10. I also hope to update the .ADF image of the floppy, also of the v6.10 vintage. I expect them to remain electronic, but a cheat-sheet 1-page install instruction guide could be part of the package. I have yet to produce any PCBs, but have the necessary files. I will be personally building the adapters and testing them. I am hoping to order all parts for the first group before taking two personal trips at the beginning of February and mid-February 2018. I am hopeful to have something ready by March 2018.

This GuruROM adapter and omniscsi.device code supports the GVP Series II A500/A2000 SCSI units, and the 68030/68040 accelerators + SCSI for those systems, along with the Commodore A2091 and the A590 (possible physical clearance issues with the drive. The GVP A1208 unit is code-supported, but none have been available for testing - more detail to follow in the v6.16 details (further down).

Edited: I have worked an agreement with blindgerman in Germany to handle Germany, and approximately the southern and western continental Europe. I have worked an agreement with tbtorro in Denmark to handle the approximately northern and eastern European zone (including UK), and 'Worldwide', except for the USA/Canada which I will handle.

Regarding the v6.16 omniscsi.device driver/ROM: If you have v6.14 (or even any version v6.11 or later), you have the primary TD_64, SYNC SCSI, and (for C= controllers) the improved DC/RC and 24-bit DMA copy-up to >16MB RAM feature support, and generally don't need anything newer if all is well. However, for those that just gottahavit - I will include taking interest orders for ROM burning service Only - the cost of the EPROM part, and the shipping cost - in this same thread. I do not have authority from Ralph Babel to post the driver on the web or e-mail it. The latest version that is posted on Ralph's website (at time of this post) is v6.14 (weblink is further down), and is suitable for anyone with a past GuruROM adapter and their own means to burn an update. More details on the v6.16 ROM, who might consider the update, who shouldn't, and why, are further below. I also plan to link in some of the other discussion board threads for reference.

Edit 2/16/2018: I have the v6.16 individual images now for the controller-specific adapters, in addition to the Speedgeek universal adapter image. The adapter-specific versions are burned into 27C256 (32K) components, and the universal image for the newer model into a 27C512 (64K) component. Specify the type of adapter you have in the request.

This is for PRE-ORDER Interest. No payment at this time, no need to PM (Questions PM are welcome). Reply in the thread with interest in either:

A. GuruROM v6.16 (ROM+Adapter)
B. Burning Service (V6.16 ROM Only)

and also include the country you would have it shipped to, and quantity. This will permit research to be done on the shipping costs.
The model of the destination controller is suggested. I will try to set it for your type, or build the shorter version for A590's, if mentioned.

April-27, 2018 - pre-orders are very close to the number of PCBs I have from the first order. More have been already ordered, and in the event that pre-orders exceed the current group, there will be another production done this summer or by fall 2018, but definitely after I move apartments (end of May 2018 ).

Aug 19, 2018 - getting settled after the apartment move and putting my work space back in place to complete the modules has been a personal challenge. I do have the second PCB and part group in hand, though, so both will go out at once when I can get them built and tested. On the other hand, I know first hand that the forthcoming AmigaOS update will not present any issues with GuruROM. A nod to Ralph and his coding. Added the interested peeps to the list from this summer.


Name / Destination / Qty and Item (placeholder)

------Start of Group 2-----Interests After May 21st 2018-----

- Sale Thread Page 8 Start
mackbw - USA -2x GVP ROM+Adapter, 1x A2091 ROM+Adapter
volker - Germany - 1x GVP ROM+Adapter
JagLally - UK - 1x GVP+Adapter, 1X A590+Adapter
nonamez78 - Germany - 1x GVP ROM+Adapter, 1x A590+Adapter
Bitboy - Denmark - 1x A2091 ROM+Adapter Withdraw
- Sale Thread Page 9 Start
WonkeyDonkey - UK - 1x GVP ROM+Adapter
rootboy - USA -1x GVP ROM+Adapter, 1x A2091 ROM+Adapter
Valfac - Spain - 1x GVP ROM+Adapter
SegaCD - USA - 1x Adapter+ROM - GVP
ethan - Germany - 4x Adapter+ROM (2 GVP, 2 A590)
- Sale Thread Page 10 Start
Tomcat - Germany - 1x Adapter+ROM - A590
britlord - USA - 1x Adapter+ROM - GVP
nekonoko - USA - 1x Adapter+ROM - GVP
- Sale Thread Page 11 Start
thufir - Germany - TBD
Multianer - Germany - 1x Adapter+ROM - GVP
maw2k - Canada - 1x Adapter+ROM - GVP
Jaegermeister - Austria - Adapter+ROM - A590
- Sale Thread Page 12 Start
CStich - USA - 2x Adapter+ROM - GVP+A2091
cemi - UK - 1x - Adapter+ROM - GVP - A530
gertsy - Australia - Adapter+ROM - GVP - GF040
- Sale Thread Page 13 Start
Jim_Oregon - USA - Adapter+ROM - GVP-HD8
- Sale Thread Page 14 Start
gounderset - Norway - GVP - GF040
Dellamort - Australia - 3x Adapter+ROM GVP HD8 & HC8 (Same setting for both)

For tracking purposes, interests after May 2019

madk71 - UK - Adapter+ROM - GVP - HC8 (From PM)
Huxley - USA - Adapter+ROM - GVP-HD8
PuppetMaster - Germany - Adapter+ROM - 2x GVP A530 (From PM)
Springycz - Czech Republic - Adapter+ROM - A530 (Updated PM)
TjLaZer - USA - Adapter+ROM - A2091
omnicron10 - USA - Adapter+ROM - A530
Thomas70 - Germany - Adapter+ROM - GVP 030
marco920 - Italy - Adapter+ROM - GVP
nikoskon74 - Austrailia - Adapter+ROM - GVP
na103 - Italy - Adapter+ROM - GVP
Finntuitive - UK - Adapter+ROM - Not defined
Pages 18-21 interests and inactive through January 11, 2021.

Thomas70 - Inactive
Ralphfwd (email): Jochen Franz, Germany, TBD
arnljot - Oslo/Norway? - G+A A500HD8
ahandyan59 - inactive
apex - question - patch for Mulibs? (1-April 2020)
SegaCD - inactive
Bladejack - Ireland - G+A A500HD8 (dupe on p19)
Ralphfwd (email): marco_21, Poland?, GVP030
Dellamorte - inactive (had multi-interest)
Nowee - France - G+A TBD
Fabbry - ITaly - G+A GF030
Lukeya - UK - G+A HC8
hayalan52 - Austrailia - 2x GVP (active again 2021)
Haider - inactive
Kiro - inactive
cdhooper - inactive
Cloudscout - USA - G+A A2091
Dale423 - USA - 3x G+A - A2091/A590/GVP
Ralphfwd (email): Luca Bertaccini - Italy? - GVP030 (email)
alexh - England - gvphd8
roc - italy - a590
quantum8 - Australia - gvp
ComPete - Germany - ROM Burn Svc
Toaster-4000 - Seattle - USA, GVP & A2091
pedro.rocha - Portugal - GVPhc8
Chicken - Ireland - GVP
>Ralphfwd: Graham Prout - UK - GVPHD8 (email)
PBobbenB - Sweden - GVP
Interests Updated as of Feb 25, 2021

Rakeim132 - Austrailia - 2x (GVP+A2091)
hardcore8uk - UK - GVP
cyberstormer - Germany/Swiss - 2x - ?
Gumboots - Austrailia - GVP
Sandro - Germany - A2091
Marco06 - France - GVP
Hanibal - USA - A2091
BEAViSX - Canada - A530

Interests Updated as of April 24, 2021


notsosimpleme - Japan - A2091
tstark73 - Italy - A2091
flip971 - Italy - GVP A530
Milesunder - UK - A530 - Note: there is no GuruROM update for TekMagic - see your PM for an explanation.
mihgermany - Germany - 2x GVP
Picard - Interested - Need type.
Travailleur - Austria - 3x - A530, GF-040, A2091

Interests Updated as of November 2, 2021



The USA/North America price will be $47 before shipping.
(Confirmed 21-Mar-2019/Updated May 2019) 47 48eur per unit plus shipping will be cost in Europe and the rest of the world.

I don't see any changes in price on my side, and hopefully it stays the same for the overseas distributors.

USA domestic shipping is $7.90 using the USPS flat rate box (comes with $50 insurance if I recall correctly), or I can investigate the 1st Class rate options for the package to your address when you reply in the PM I send.

Investigating Canada shipping, it's ~$11 First class padded envelope w/o tracking or insurance. Flat-rate small box option starts at over 1/2 the price of the actual adapter, so I don't feel right offering it unless you buy several. I expect to be at the TPUG WoC show in December 2019 in some casual capacity, and may have a few with me.

Past History:

27-Jan-2018 - Added a pic of the module and the ROM - that is my own Speedgeek-provided module from the last batch he made.
28-Jan-2018 - Some additional details and clarifications continue to be added to the detail further down as I validate what I remember to what actually is.
30-Jan-2018 - Received an e-mail that PCBs are in manufacture.
6-Feb-2018 - I have updated much of the OP feature/support notes for anyone who read it first late last month.
16-Feb-2018 - PCBs have arrived, two are built & tested.
22-Feb-2018 - Brief stop by to check thread. Still traveling.
28-Feb-2018 - Clarified some requests in PM, others still pending.
21-Mar-2018 - Ralph confirmed GVP A1208 code compatibility is in GuruROM, but untested (physical fit of the adapter also not tested); he confirmed GuruROM is not compatible with the A1230+ JAWS II SCSI (also physically incompatible with the PLCC EPROM socket).
25-Mar-2018 - Added some settings (or a lack thereof on the PCBs) notes regarding the SMC 'Combo' 68030 boards.
27-Apr-2018 - Status update, and some post #1 edits. Also added other interests to the list since last update.
21-May-2018 - I counted 49 adapters, so marking any more as Group 2. I have the replacement GAL parts in, but I'm moving apartments. I'm going to try to finish the last few and get them out as I move. Updated documentation still lagging behind, but I have a good amount done.
10-Jul-2018 - All delays my fault, mainly due to moving/unpacking/travel and other personal items that had me focused elsewhere.
19-Oct-2018 - Getting updated utility/tools modules from Ralph since the v6.10 release I had, including GVPCPUCtrl which was updated in September. Query made to Hyperion regarding inclusion of newer HDToolBox/FastFileSystem components & ShowConfig tools from OS 3.1.4 (expecting a no response, but still remotely hopeful, since I'm an official Amiga developer, beta tester, and Ralph is still The Guru).

Update 19-Mar-2019 - I am getting to most of the 'first group' users with a shipment to blindgerman (Germany/nearby EU) including the ROM burn service users, and in turn to tbtorro (Northern Europe/World). I will get to the USA people in that group directly. There is about 40 adapters in hand that are completed.

Update 23-Mar-2019 - blindgerman has the shipment, and is attending a retro computer festival in the Germany? region. He will address the first-group interested parties there that he knows personally. Payment/Shipping coordination for the remainder of his group (Germany and south/west European continent) will occur this week. The shipment to tbtorro will also occur, which is expected to allow him to cover most of Group 1 for the UK, Northern and Eastern Europe, and the remainder of the worldwide locations.

Mar 21, 2019 - blindgerman reports the package has arrived in Germany, (Edited:) contact/coordination/shipping in progress. tbtorro will also have his allotment shipped off soon. Blindgerman's contact/distribution status post is #117 & 120 in this sale thread, on page 12 & also on #13. I will try to keep the page 1 updated. (I will post tbtorro's status post once he gets the shipment and starts contacting). Please leave feedback once all transactions and any issues are addressed.

My 2018 Delays Explained: In the mid-later part of 2018, I moved apartments again (this sucks - 3 states, 4 places, in 4yrs), and then ran into parts/testing problems, work (merger/uncertainty) and personal (back) problems, overall logistics issues (incl. updated sw tools delays), and a push to beat on OS 3.1.4 (particularly AutoConfig HW). Suffice to say I had to constantly put this aside with so many things happening. I'm glad I didn't take any money up front.

January 11, 2020 - Added purchase interests and updated the withdrawals. I posted a link to my DropBox with a .ZIP archive with the basic tools off the support thread (see the top of this post). Nothing earth-shattering in them, but are available for those that needed them. I have not had opportunity to build modules more during my hiatus since the first batch, but I hope to get back to them in the near future. So there is some idea of my attention being elsewhere, I didn't turn an Amiga in my place on from September 2019 onward, and I just did again in the past week. I also was working on an updated GVP ExpertPrep over the summer 2019, but that, too, has been on hold since then.


Completed Transactions:

These were in the first group - I believe they are completed transactions, or no-reply If you are in this group and did not respond to the contacts, please re-enter the interest list,

shaf - Canada - 1x GuruROM+Adapter (A2091) (responded Apr 7, shipping quote sent Apr 17, awaitng reply)
- Sale Thread Page 3 Start
Oldskool1 - 1x Netherlands - GuruROM+Adapter - (A2091) (blindgerman emailed)
Durniplot - 2x Norway - GuruROM+Adapter - (A590 & GVP) (tbtorro PM payment info sent by May 11)
- Sale Thread Page 4 Start
Assahi - Czech Republic - 2x GuruROM+Adapter (GVP & A590) (tbtorro PM payment info sent by May 11)
chain - Czech Republic - 1x GuruROM+Adapter (A590) (tbtorro PM payment info sent by May 11)
- Sale Thread Page 5 Start
Morphfrog - Sweden - 1x GuruROM+Adapter - GVP (tbtorro PM payment info sent by May 11)
ElectroBlaster - UK? - 2x? GuruROM+Adapter - A590+GVP (tbtorro PM payment info sent by May 11)
- Sale Thread Page 6 Start
timtheloon - UK - 2x GuruROM+Adapter - A590(tbtorro PM payment info sent by May 11)
- Sale Thread Page 7 Start


USA / Completed:

BlindGerMan - Germany - 2x GuruROM Burn Service (Source: PM, for 1x GVP, 1x C=, Original adapters assumed) - Distribution for Germany and EU to the west/south. (shipment arrived for distribution after April 1, 2019)
Acill - USA - 1x Adapter+GuruROM - *either (we have already traded HW/SVCs)
caseybarker - USA - 2x GuruROM+Adapter - GVP (Completed/Feedback left)
Miru - USA - 1x GuruROM+Adapter - GVP (Shipped Apr 9, tracking provided)
- Sale Thread Page 2 Start

Blindgerman / Completed:

Cyborg - Germany - 1x GuruROM+Adapter (Reduced to 1, GVP, Source: PM) (blindgerman shipped by Apr 17)
sinsaner - Germany - 2x GuruROM+Adapter (A2091 & A590) (blindgerman shipped on/before Apr 9)
aPEX - Germany - 2x GuruROM Burn Service (A530+A2091) (blindgerman shipped on/before Apr 9)
arxxxx - Italy - 2x Adapter+GuruROM (A2091, and possibly a second, GVP) (blindgerman shipped on/before Apr 27th)
gseb - Germany - Germany - 1x ROM burning Service (C=) (blindgerman shipped on/before Apr 9)
bubbob42 - 1x ROM Burning Service (A2091) (blindgerman shipped by Apr 17)
ludovicfrance - France - 1x Adapter+GuruROM - (GVP) (blindgerman hipped on/before Apr 9)
Straubuli - Germany - 1x GuruROM+Adapter - A2091 (blindgerman shipped on/before Apr 9)
Mustang - Germany - 1x GuruROM+Adapter - GVP (blindgerman shipped by Apr 17)
Starvak-Sp- Spain - 1x GuruROM+Adapter - GVP (blindgerman shipped by Apr 27)
kaosoverride - Spain - 1x GuruROM+Adapter - GVP (Confirmed arrvied 16-May-19)

tbtorro / Completed:

tbtorro - Denmark - 1x GuruROM+Adapter - GVP - My Distribution point for Northern and Eastern Europe/UK and worldwide (non-Canada/USA). Shipping Mid-May 2019.
Rave- UK - 2x Adapter+GuruROM (GVP & A590) (User Reports Received)
Morten- Denmark - 1x GuruROM+Adapter (A2091) (User Reports Received)
cjhall2004- UK (Wales) - 1x GuruROM+Adapter - GVP (User Reports Received)
PRS - Netherlands - 1x GuruROM+Adapter - GVP (User Reports Received)
luuvaurio- Finland - 2x GuruROM+Adapter - A590+GVP (User Reports Received)
Buckers - UK - 1x GuruROM+Adapter - GVP (User Reports Received)
- Netherlands - 2x GuruROM+Adapter, one each GVP & A2091 (User Reports Received)
breech - Australia - 2x GuruROM+Adapter - A590+GVP (User Reports Received)
Yougorin - Poland - 2x GuruROM+Adapter - GVP (User Reports Received)

Withdrawn Interest:

cktwo - Germany - WITHDRAWN INTEREST (Found earlier adapter model elsewhere)
kirk_m - USA - 1x GuruROM+Adapter (GVP) (FB 1:1 Mar 28, 2019 - declined/already found one)
wmaciv - USA - 2x GuruROM+Adapter - GVP (Withdrawn/HW sold)
scrappysphinx - UK - Withdrawn
mic72 - Germany - 1x Adapter+ROM - A590 - Withdrawn

USA Group 1 Interests that never responded to at least two 1:1 contact attempts by me over 1.5 months:

SpeedD408 - USA/Florida - 1x GuruROM+Adapter (GVP) (PM sent Mar 17, 2019, followup PM Mar 28, No Response)
Chance66 - USA - 2x Adapter+GuruROM - (GVP, A590) (PM sent Mar 17, 2019, followup PM Mar 28, No Response)
nexus - USA (south) - 3x GuruROM+Adapter (type TBD/both?) (PM sent Mar 17, 2019, followup PM Mar 28, No Response)

You may re-enter the waiting list at the bottom.


I will attempt to get adapters set to your unit type, but check the jumper anyway.

For those interested in the ROM Burning Service, please mention your adapter type (Original Commodore, Original GVP, or the newer Speedgeek adapter with the selection jumper).

I will be using a stock A2091 and an HC8 together in an A2000 system, each with 2MB RAM on board, for my build testing.

I will be including a spare machine-pin socket on the base of the standard adapter to help provide a good socket fit and to make my testing with a ZIF socket easier. Use of the socket is optional if the adapter remains well seated in your board's ROM socket without it.

I have succeeded in building an A590 version with just machine pins (no spare socket under) to reduce the adapter height to an absolute minimum. Visually it is lower than the standard adapter, but I do not have an A590 to test with to see if it fits under the metal shield plate. I may include either a pair of machine pin headers or a socket in the event the shield doesn't matter (removed or cut) but a good seating matters.

March 25, 2018: About 4/5 of the 50 PCBs have been built, including most of the A590 machine-pin-only variants. Manual rewrite still in progress, testing utility software command syntax and confirming defaults. Floppy ADF I still need to address, but RSCP 1.14 with the selectable target buffer memory option will be included (was previously a custom alternate build provided only on the v6.10 GuruROM Floppy) thanks to SpeedGeek's most recent efforts. Also looking to include some of the useful system tweak tools Speedgeek has created that may improve copy-up and CPU cache performance. I have sent Big Book of Amiga Hardware a preliminary GuruROM page, and it will be the likely point for the manual download link to get posted. I am still working on the details regarding the updated floppy image.

April 11, 2018 - Ran into GAL programming problems (either my programmer, the parts, or something) after building the last 8 adapter boards over the past weekend. New parts on the way. Shipping in bulk to my distribution points will occur as soon as these are completed. My euro distribution point will have a few extra adapters on hand once this shipment goes out - this helps manage the shipping overhead costs. I hope to make another batch toward the end of the late spring or early summer (northern hemisphere) depending on demand/interest. Big Book of Amiga Hardware GuruROM page has the basic jumper setting info applicable to GuruROMs. The updated manual document(s) will get hosted there, too. Support tools format remains undetermined - either an .ADF or an archive, but there will be some Speedgeek performance-tweak utilities (optional, for specific CPU uses) added, and the RSCP v1.14 benchmark tool.


What's New in v6.16?

This version is equal to v6.11-6.14 if you plugged it in without any system changes. Unless some of the hacks are your focus, there is no purpose to getting it in place of those more recent versions. It primarily focuses on additional support for the A2091/A590 14Mhz DMAC hack as discussed on various other discussion boards. It also can benefit performance from some out-of-spec settings on some hard disks under Async SCSI. For the curious: The GVP DPRC code version of the driver was kept in sync with the DMAC version, but no changes occurred since 6.14. There is also an undocumented hack that could increase the G-Force 68040/33 SCSI/DMA interface performance, but it is known to be fully incompatible with any 16-bit FastRAM Zorro II memory installed in the Zorro II expansion slots, so not a worthy hack in most cases.

What GuruROM provides:

- It provides SYNC SCSI negotiation where the FastROM and C= ROM supported only Async SCSI protocol. Under normal conditions, Async SCSI would be limited to about 2.3MB/sec theoretical limit (on the SCSI bus) based on the system clock that drives 33C93A. Sync brings the potential transfer rates up into the low to mid 3MB/sec range, if other conditions are optimal, on Zorro II slot cards.
- It provides all-in-one driver support for both the GVP DPRC chip and C= DMAC chip controllers. That is the GVP Series II SCSI products and the SCSI-based accelerators for the A500 and A2000, and Commodore's A2091 and A590.
- It provides the TD_64 large disk support API for newer file systems that support it. You still need to heed the limitations of the file systems you use with regard to their abilities to address large partitions. Know also that you may need lots of RAM for those partitions to validate and mount.
- It provides more efficient DMA copy-up of data to/from 32-bit RAM located above 16MB than the typical C= FastFileSystem DMA Mask method, which would fail anyway in SCSI_Direct communications (sorry - it was a hack). GVP's FastROM driver already handled this copy-up situation. This copy-up behavior includes support for A3000 and A4000 environments (Note: some 16-bit FastRAM on the board, or in another slot, is recommended for best performance, or programmed I/O is a last-resort option).
- It provides support for all Motorola 680x0 CPUs, including utilities to support the known non-standard 68000-cache implementations (ICD AdSpeed/Supra 28Mhz).
- It supports all versions of the 33C93A chip with Disconnect/Reconnect, with most known bugs worked around even on the -03 and -04 versions, which caused problems in multi-device situations for many A2091/A590 systems unless using both the -08 33C93A chip and the latest C= ROMs.
- It provides support for setting DMA transfer thresholds (a chunksize option in GVPSCSICtrl) in situations where trading off I/O performance for more responsive CPU interrupt servicing is deemed more important. This effectively releases the bus back to the CPU after the trigger threshold, and lets the CPU service an interrupt, before the controller re-requests the bus and it gets granted.
- RDB & Autoboot compatible with KS 1.3 and newer.
- Diskchange support (With OmniscsiCtrl) for removable media between identically partitioned and formatted media.

Known Incompatibilities
- Some early DMAC chips with -01 markings did ship (I've read about a very few A590's). You must move up to the -02 DMAC chip. A seller here on Amibay has some stock.
- The A590 may have a height problem with the ROM+Adapter in terms of the internal RF shield plate holding the drive. If you have an A590, mention it in 1:1 at the time and workaround solution may be available. I don't have an A590 to hands-on/physically verify with. Ralph's off-site reference link to adapter use in an A590 is here:
- If you have an expansion, or accelerator, with FastRAM placed in the $200000-9FFFFF FastRAM area, and it does not support DMA, it will not be compatible with either controller - i.e. not something a GuruROM can solve. Some more recent (21st century) accelerator products that go into the 68000 socket, and have FastRAM mapped to the noted (low) Zorro II FastRAM memory region, are examples. Ask if you have any doubt.
- If you have improper SCSI-bus termination, the higher speeds of Sync transfers will likely cause issues. The cable is the bus; the controller and all peripherals are devices on the bus. The bus gets terminated at the two most distant points, no Y allowed. Some controllers (most GVP, except G-Force 040) don't have removable terminators by default, and that reduces your options as to where the bus needs to start and end.
- Some very early (numerical Rev 1 two-layer, & the Rev 2 four-layer) GVP HC8 boards are built without a U8 74F244, which buffers the on board RAM's address lines. These HC8 boards are likely have the Motorola-logo (only) of the first run of DPRC chips, before the GVP logo appeared. Instability with eight installed 30-pin modules of the 8-chip type, and a slower (larger value) than 80ns speed, has been seen on occasion. Use of 80ns or faster RAM, and/or (preferably) of the 2-chip per module variant, was the workaround. It was determined to be a chip-count load-issue on the address lines of the DPRC. The later Revisions (Rev 4, 5, and the surface-mount I, and II) have U8, and there are no issues with a full load of 8-chip modules. The parity chip on some PC modules is not a factor/not connected.
- GuruROM does not support the GVP Series I Impact boards (Buffered I/O). Continue to use a FastROM 3.x.
- GuruROM does not support C= A2090/A boards. I have read about another 3rd party that had a replacement driver ROM set that was OS 2.x+ compliant.
- GuruROM does not support any XT drives on either the A590 (most popular) or the A2091 (not normally an option/no header).
- GuruROM is not the proper form factor for the A1230 JAWS-II 68030 Accelerator products. The product code is not recognized by the driver even if an adapter were possible.

Known Limitations

There are a few areas where the addition of GuruROM won't improve I/O performance over the existing C= ROM or FastROM v3/v4.
- Async SCSI (only) devices like SCSI2SD v5 and earlier, physical disks that did not support Sync SCSI, and/or older drives which had media transfer rates <2.5MB/sec. It should not harm performance, but it may not add anything, either.
- If you only have a 512K-2MB ChipRAM system (no FastRAM), performance is primarily limited by the ChipRAM bus which is slightly slower than 16-bit FastRAM at any given time.
- If your only FastRAM is 32-bit RAM mapped high over the 16MB address line (as in A3000/A4000 systems and some other 3rd-party accelerators), the same limitations apply, as you still end up transferring data through ChipRAM buffering. Some FastRAM memory on the card, or in a Zorro Slot, is recommended in both these situations to gain an improvement even with your existing driver ROM.
- For Zorro II slot expansion DMA SCSI interfaces and 32-bit RAM above the 16MB (24-bit) address space accelerators - The copy-up function to transfer data to 32-bit FastRAM >16MB address line imposes a theoretical speed limit of ~1/2 the speed of the Zorro II bus (SCSI read DMA to ZII 24-bit DMA memory, CPU then copy out/write in to 32-bit RAM, or the sequence in reverse to write). This means the Zorro bus must split it's 3.5MB/sec theoretical max in half for the double-copy operation, and from there your mileage will vary, and is based on the 32-bit CPU's clock speed, and it's 32-bit RAM performance, plus other system overhead demands. This is still an improvement for C= cards relying on a filesystem-based DMA mask buffer, but offers no further copy-up improvement to GVP Zorro II boards over a FastROM, which will do the same double-copy in/out of the Amiga DMA-capable memory buffer.
- The GVP Combo22/Combo33 Rev 3 - This is the first version of the Series II SCSI & 68030 accelerator board, which had a surface mount CPU and cost reduced PCB, and 7Mhz clocking of the 33C93A (no 14Mhz option). It had a hardware bug where DMA to the high-mapped (>16MB) 32-bit RAM was broken. DMA transfers sometimes wrapped over motherboard RAM addreses. GVP replaced the v3.12 initial driver ROM for this board with v3.14 to address it (and recommended having some 32-bit memory mapped as Zorro II). Effectively all SCSI DMA transfers to the >16MB range operate in the copy-up manner of the previously noted Zorro II DMA boards through a DMA-compatible Zorro II AutoConfig mapped memory buffer (preferably the 32-bit FastRAM on the accelerator board) if the final destination is a >16MB memory address. The GuruROM uses the same method of handling these kinds of transfers on this board. The similar-made Combo 030 Rev 4, and all of the G-Force (w/PGA socket CPU) SCSI+Accelerator boards are not affected by this bug, w/DMA directly to 32-bit RAM anywhere being valid.
- Devices offering Fast SCSI (but not Sync) will not take advantage of a Sync transfer performance improvement opportunity.
- Ralph Babel has some theoretical transfer I/O performance data here:, the v6.14 code download, and, if needed, the earlier GVP v3.x/v4.x FastROM code images are also on the page. The RawSCSI benchmark tool mentioned on his site link show benchmarks from a pure SCSI device with on board cache/buffer to the SCSI controller chip. It does not involve the drive media/heads, nor the host bus adapter system bus. Flash media devices (and most interface adapters for them) typically will not run the RawSCSI benchmark due to there being no buffer/cache on the target SCSI device.
- The surface-mount CPU Combo 22/33Mhz boards, both Rev 3 & Rev 4, do not have any clock jumper options for the 33C93A, and that chip is default clocked at 7Mhz. The native driver and GuruROM are both aware of this. This puts a performance limit on this model's onboard SCSI interface. Make the other features of GuruROM (TD_64 >4GB media support, other C= controllers in the system, etc) the reason you seek it, or continue to use the native driver ROM.
- Due to bugs in Super Buster & early A3640's, and possibly some other A3000/A4000 CPU slot accelerators in A3000/A4000 units, Zorro II DMA is defaulted 'off' to the 32-bit ChipRAM when a non-68030 CPU is detected in these big-box systems. The driver uses DMA via 24-bit FastRAM first, and then Programmed I/O as a last resort, for transfer destinations it cannot directly DMA to. The GVPSCSICtrl utility can override the default for DMA to ChipRAM for testing and (if stable) be called during the startup-sequence boot.

Areas Of Potential Improvement with a GuruROM

- If you have a SCSI to SATA, IDE, or Flash memory interface, and it is known to support SCSI Sync protocol, then transfer rates >2.5MB/sec, into the lower 3MB/sec range, have been seen in stock 68K systems. The same goes for some server-class 7200RPM and 10K SCSI mechanical drives. The key to improved performance (speed) is media transfer rates on devices which can sustain the higher MB/sec, and have the SCSI Sync protocol support. The GVP Dual Port RAM controller (DPRC) on an A2000-HC8 and an A500-HD8 (w/RAM installed) can pull >2.5MB/sec transfer rates in stock 68K systems while the CPU availability (to FastRAM) still remains high (>75%) in those situations. C= A2091's have seen benchmarks into the low 3MB/sec region (CPU availability will of course be very low at those higher rates).

- C= controllers with multiple devices which had experienced SCSI bus lockups due to disconnect/reconnect problems (and needed to disable it and suffer poor device multitasking I/O) this will address >99% of the bus lockup problems, and allow DC/RC to function properly with any 33C93A chip.

- Better control of per-SCSI device Sync/NoSync, Disconnect/NoDisconnect, 3rd party 68K Cache Flush (accelerator) control, plus DMA-chunksize control for use with CPU interrupt-sensitive functions via the OmniSCSICtrl tool and/or the enhanced functions of the provided GVPSCSICtrl tool.

- Large HD support (TD_64) with applicable file systems.

- Mountlist or RDB Partition definitions for Mask value can be set the maximum 0xFFFFFFFF, and MaxTransfer to 0x7FFFFFFF - GuruROM handles everything internally and optimally. Any smaller value may limit performance. With Amiga OS 3.2, you WILL need to update these values with HDToolBox on newly-partitioned disk media, and may need to override some protections in the icon tooltypes, plus add omniscsi.device to the target driver name.

Hack Support

This portion is provided as-is, no warranty, Your Mileage May Vary (YMMV), may not work, and you may damage your PCB performing any hack, or be forced go to emulate the Guru in the corner. You may corrupt partition data if some variable isn't accounted for. Have full backups, and test heavily for stability.

- The 14Mhz A2091 Speedgeek Hack - This physical A2091 modification has been posted here on Amibay:! - The basic 14Mhz 33C93A hack update, which only involves J201 with a cut and a jumper, yields good results into any FastRAM. The A590 can have it done, too (read the online details - it's not for the casual tech), but a more elaborate modification is necessary to make all of the connections. For the full A2091 hack effort mentioned in the link, it involves reworking some clocks with GALs and other circuits, requires FastRAM in the system (the A2091 RAM Hack is mentioned later in the threads) that can support an out-of-spec Zorro II bus DMA transfer clocking to 32-bit accelerator memory that supports it. The driver supports this if system conditions permit.

- Async SCSI Transfer Window Hack - This has also been posted on other forums. There is a means to force some A2091/A590 Async SCSI communications with some devices to transfer with an out-of-spec SCSI transfer window. The driver can support this if the device also supports it and can benefit from it. Synopsis: In some cases, where Sync transfer windows didn't negotiate an I/O transfer improvement, this hack sometimes improved transfers >2.5MB/sec in single-device + controller situations on capable devices. It most certainly could cause problems in multiple-device disconnect/reconnect situations, and is not recommended in those environments.

- GVP G-Force 68040/33 DPRC up-clock. Moving a particular jumper on the accelerator board up-clocks the DPRC to 14Mhz, similar in concept to the A2091 14Mhz hack to modify DMAC to transfer faster. The on board 32-bit RAM & DPRC may support this hack (14Mhz DPRC function was technically never factory tested), and >3.5MB/sec transfers have been seen in test benchmarks. However, ABSOLUTELY NO compatibility exists with any known Zorro II slot FastRAM board in existence when present in the A2000 expansion slot system. It just won't boot. The 14Mhz DPRC hack is not applicable to any of the GVP 68030+SCSI accelerator boards - it is known to be unstable/corrupts data transfers. The behavior with a Zorro II RTG board in a slot is also unknown.

Misc Features and Functions You May Not Have Known About

- The driver ensures it's located itself in 32-bit RAM at boot time if the RAM was in the memory pool at boot time (not AddMem'd).
- The HD_SCSI_CMD/SCSI Direct standard is supported just as it was under scsi.device and gvpscsi.device.
- The driver detects and software-maps the >16MB addressed 32-bit RAM on GVP 68030/68040+SCSI Accelerators.
- The driver detects and software-maps the A2000 G-Force 68040 I/O extender features.
- The driver is known as omniscsi.device, and a will report a v1.16 value with the version command - this is because there is a high level (DMA chip interface to OS) and low level (33C93A SCSI) driver design, and only one of the code versions is reported to the OS version command.
- The Amiga (and most other software development) Version.Revision format is not based on the popular currency or mathematical decimal notation. Yes, GVP marketing labeled the first FastROM production and upgrade offerings with paper labels they insisted be printed with 'v3.07'. The driver always reported v3.7. They also paper-labeled chips with 'FastROM 4.0', but they only contained the then-latest v3.x gvpscsi.device and (for the A3001/A3028/A3033/A3050 accelerator boards) v3.x gvpat.device code. Eye-rolls for these sales/marketing actions are appropriate here.
- GuruROM supports a unique 4GB virtual disk configuration in the event older OS versions, and older FFS, must be used in the upper sections (>4GB) of a large hard disk - by using a 1000's digit in the SCSI ID (Unit ID) section of a manual HD Mountlist. This was described in the original GuruROM manual, and few will find use for it today with updated and 3rd party file systems, but is an option. Details will eventually make it into the revised documentation.


A note about >4GB drives and >2GB partitions:

The legacy TD_ interface provided by the C= ROM and GVP FastROM is based on unsigned 32-bit integers (the magical 4GB block limit of HDs you may have heard about), and that legacy support is in GuruROM. GuruROM also provides the driver framework (TD_64) needed for devices that have block counts >4GB (and for applicable file systems to be able to support >2GB - the Native FFS size limit). You must still heed some limitations depending on your choice of OS environment. The driver also supports the SCSI_Direct API, which some filesystems use to overcome the limitations of the trackdisk-like TD_ functions mentioned previously.

- Always consider making your first partition <2GB, and using FFS. This offers the best compatibility with older Kickstart-based FFS that may not be patched or updated in emergency situations, and gives you easy access to potential support tools. Native FFS won't know how to deal with >2GB FFS partitions (or FFS partitions located at media positions >4GB) and will either corrupt the partition, or data-wrap over the first 4GB media space's partitioning (because it would only know the 32-bit TD_ functions). If you Kickstart-select to KS 1.3 or 2.x, consider it a mandatory practice unless you know exactly how your alternate file system will behave, and what to do if something corrupts it. Make sure any boot-block inserted file system (typical for FFS in the KS 1.3 era) is compatible with your earlier chosen Kickstart. There are DosType values in Mountlists and the RDB partition definitions that identify the versions of the file systems they match. Recognize and understand them. If a particular file system is not available to load at the time all partitions are mounted at boot time, they won't mount. If it's incompatible with the earlier OS version, a visit to the Guru is likely.

- Avoid crossing the 4GB line with any file system partition without fully testing all of the partitions with data validation. Safety first.

- FFS is known to be a memory hog for multiple large partitions (particularly at boot/validation time). Realize this before putting (for example) a SCSI2SD with a 16GB SD card in, slicing it into four 4GB disks (to be seen as 4 SCSI IDs), and then partition each 4GB drive into two 2GB partitions, netting eight 2GB partitions. 2MB of FastRAM just might not be enough. NEVER try to boot the system with them active and without enough RAM - you risk corrupting some partition(s) when you run out.

- If using a SCSI2SD (any rev), consider using its ability to slice up the memory card to it's best effect: Only use one version of file system for each disk slice (SCSI ID). You can then load boot blocks of each 'disk' with the appropriate file system (if supported). Then use the partition tool they recommend without fear of altering other partitions on that same 'disk' with other filesystem(s), or having unwanted behavior of a specific file system affect other partitions of the disk media. You could make disk #1 4GB, partition as 2x FFS partitions. Partition the remaining ~12GB disk for use with PFS or SFS, in any supported partitioning layout, for example. Just heed the next note:

- Know your partitioning tools, and try to stick to using only one (i.e. per 'disk' or SCSI ID). GVP FastPrep can be made to work with this driver with an icon ToolType, or provide the driver name (in lowercase) on the command command line as an option, but do not attempt to use it for >2GB partitions, or >4GB target disks. It's only a 32-bit partitioning tool, as are the earlier versions of HDToolBox. Later versions of HDToolBox (Post Workbench 3.1 era) made to work with patched C= scsi.device can be used if you have access to them, or follow your 3rd-party file system's guidance. "HDInstTools" (disk/misc/hdinst.lha on Aminet) is another option. If you have Amiga OS 3.1.4, 3.2, or newer update, use the HDToolBox on that distribution for larger partitions.

As I go through the support tools, I will have an updated GVPCPUCTRL v2.6. It has some improved error code responses over the version I was going to include. Also note that anyone using TekMagic 68060 boards, the 68060.library on Raplh's site got updated - it now recognizes the Rev 5 CPU mask (like MuLibs now does) and sets Load/Store Buffer Bypass mode off (CPU errata). Ralph and I have sorted through the tools disk contents, and he's informed me that there were updates on a number of them. I am expecting them soon.

Another item that sill burns us all today on modern computer hardware: Backups. Plan how you are going to back up, particularly large partitions, so that in the event of problems you can recover.

Post OS 3.1.4 release has brought forth a little bit of wisdom. I posted in my Retro Computer Support Memories page (on Facebok) something similar to this: Just because you can now create 250GB FFS partitions, doesn't mean it's a great idea in practice. Why? The validation of your FFS partitions must occur at each boot time. That means many little block reads of the disk as it reads all of the partition's file system allocation table data. I can tell you that a 71GB partition, on an Intel SSD, via an SATA2SCSI adapter that can get good performance number, off an A4000T with 68060/60 takes 25-30 seconds at boot time with 512bye blocksize settings. Mechanical drives, and slower CPUs, will be even worse. Bump any Solid State/Flash filesystem block size to a minimum of 4096, or a multiple of that size for much larger partition sizes.

April 8, 2019 - ROM+Adapters are starting to go out after contact/payment has been made in the first Group. I still need to post the updated tools and documentation. tbtorro is awaiting his allotment to ship to him - sorry for the logistics delay.

Summer 2019 - I have gotten access to the last GVP FastPrep 2.5x source code. I am working on modernizing the tool, but it will take some time as I re-learn C, and the time permits some coding efforts. I want to get the next group of adapters built, tested, and out this fall.

January 2021 - Page 21 post #204 has my explanation as to what has been going on in my personal life, and the reason for my large amount of inactivity here on Aminet since last update. Production has not restarted, but I will keep the interest list as intact as possible, and I hope to get back to making them available. FastPrep work noted just above this also hasn't gone much further ahead.

November 2021 - New page numbering seen - On what is now Page 17, it has my note that I have started to build some more modules, and have ordered more parts. Hopefully the world will be nice to me for awhile , I'll get the batch completed, and those still interested will get the opportunity to get the adapters. No need to re-express interest.
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9   0   0
Jan 26, 2008
You have permission from Ralph? Wow. I reverse engineered the adapter years ago but Ralph emailed me and asked me not to try to sell them. It was a different world back then. You could still see them on SoftHut website but they never had stock.
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34   0   0
May 9, 2017
United States
Rhode Island
I happened to have had a unique position at GVP where I was the senior tech (under the boss, George). I focused on the SCSI+RAM+Accelerator products. That put me in direct contact with Ralph with regards to FastROM, and even an early version of GuruROM he was working on at the time. I'm sure I ran up a good bill on the phone at the time talking to him, and downloading driver code from Germany. He also called me from time to time to hammer out some English translation 'American-ism' speech in the occasional document he was processing. I'm not sure he ever slept back in that era, too (he was up at any hour).

Support-wise, I know the boards (collectively) probably better than anyone still active in the community. I have a good collection of them. Also, both Ralph and Speedgeek have noted to me that they have other priorities in their personal lives. Making them, and direct support for them is something they are not looking to do. Ralph owns the rights to both the adapter and the code at this point, although Speedgeek designed this adapter - the ones that are compact and fit nearly all applications.

I actually have interacted a few times in the past few years with the SoftHut people. I knew them well as a GVP dealer back in the day. They were in Philadelphia, like me, and the local dealer we tended to frequent. The problem was likely manufacturing and sourcing - they are a hand-solder project in this compact form. I've got the means to build them fairly efficiently. I also want to upgrade the manual and driver disk.

While I have the response space, I want to say this: This upgrade isn't for everyone's system. There are situations where bottlenecks exist in other parts of the system, and just getting Sync negotiated speeds on the SCSI bus doesn't improve anything. It may help work around problems in some cases (A2091/A590 with DC/RC issues, and/or >16MB addressed 32-bit RAM copy-up, etc). It may improve performance in other configurations. It will provide TD_64 support (along with classic TD compatibility, and SCSI_Direct) for larger disk media and newer/updated file systems. That should be the 'value' to consider. If not a value-add to what you already have, stick with your current driver ROM.
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New member
Rating - 100%
24   0   0
Jul 14, 2015
Great news!

Interested in:
GuruROM v6.16 (ROM+Adapter), Germany, 1 unit (maybe 2, depending on final item costs)


Rating - 100%
72   0   0
Nov 9, 2009
One Guru ROM adapter for the A2091.

PM with some questions.
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New member
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0   0   0
Jan 26, 2018
Sinsaner declared interesse

Sinsaner declared interesse

Interested in:
GuruROM v6.16 (ROM+Adapter), Germany, 2 Units each for A590 and A2091


Rating - 100%
34   0   0
May 9, 2017
United States
Rhode Island

Morten - PM clarification provided - thanks!
cktwo - done
BlindGerMan (Interest provided Via PM)
sinsaner - Left you PM for a clarification.


Rating - 100%
2   0   0
Nov 27, 2013
Interested in 1 Gururom + Adapter, I have Ver 6.14 on my 2091 Currently but the adapter is not in great condition.



New member
Rating - 0%
0   0   0
Jan 26, 2018
Hello Robert, (at the Moment i am not able to send Messages, my account is to new for that)
Thx for reaction.
Yes exact, what i wrote, but not what i mean...
Sometimes english is not so easy.
I only want 2, one for the A590 and one for the A2091 (Adapter and ROM).
You're right that "each" means amount per model. Sorry it's my fault.


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34   0   0
May 9, 2017
United States
Rhode Island
Added SpeedD408 to the queue. Thanks.

Note that I am away on holiday/vacation from 1/31-2/5. My updates to this thread for requests will be sporadic.


SCSI2SD Rocks my world!
Rating - 100%
13   0   0
Mar 16, 2008
2 x A. GuruROM v6.16 (ROM+Adapter) for GVP 040 board & A590 Please! :)


Rating - 100%
6   0   0
Nov 2, 2016
Interested - Italy -1 GuruROM+Adapter for A2091
and maybe
1 GuruROM+Adapter for GVP HC+8 Series II (depending on final item costs)
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New member
Rating - 100%
3   0   0
Jun 11, 2015
United States
Interested in 2 GuruROM + adapter for A590 and GVP HC Series II, shipping to 93710

Sent from my iPad using Tapatalk


Well-known member
Rating - 100%
279   0   0
Apr 3, 2012
I have the old adapter and can update/burn the rom myself.
Is there a possibility to download the V6.16 or is it a buy only update ? Thank you
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