A2091 14Mhz SCSI mod

If you have a Guru ROM it will assume the 33C93A is still running @ 7 MHz.

EDIT: The 33C93A_14MHz Util does NOT seem to work with the Guru ROM so you should use rdbctrl to set the RDB flag to ASYNCHRONOUS or for versions 6.11+ setting JP5-4 on disables the initial SDTR. Another option is to install a jumper block to switch back to 7 MHz if you really want to enable SYNCHRONOUS mode.

(Sorry this Util was a quick hack for the C= 7.0 ROMs).


P.S. If you don't have a Guru ROM but you have something faster than a stock 68000 see this thread:

https://www.amibay.com/showthread.php?t=47494
 
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I just hacked my 2091 and everything seems to be working fine...I burned a U12 eprom with the mod, and it seems to be working fine :)

my transfer speed for the drive i have in place went from 1.3mb/sec to about 1.95 that is with 1 meg of ram added to the scsi card... ( yup got it working)

Thanks again for this great thread :)

I introducted a Fusion40 into my system and it is working fine, ( it has 20megs of ram in the 32bit space) my 2091a scsi card has 2megs of ram, but now my speeds have dropped to 0.354 mb per second....

any suggestions speedy :)
 
I introducted a Fusion40 into my system and it is working fine, ( it has 20megs of ram in the 32bit space) my 2091a scsi card has 2megs of ram, but now my speeds have dropped to 0.354 mb per second....

any suggestions speedy :)

Hi waltermixxx!

Your Fusion40 has probably configed it's Fast memory as extended 32 bit memory. So you can try to config some of it in 24 bit address space (just like the A2091 Fast memory) or you can try 2 solutions already posted on this thread:

vbak2091 and A2091ToFastV2.0

http://aminet.net/package/driver/media/vbak2091

https://www.amibay.com/showthread.php?t=47494

I hope this helps! ;)
 
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neither seemed to help, i'm going to try to unmod it and see what happens... see if its worse or better than the 345k i was getting ... :)
 
** 3RD NEWS UPDATE **

The 33C93A_14MHz util in post #1 has been replaced by a new 33C93A_Config tool. Since you now have the option of using a 14MHz patched ROM or BindDrivers version you don't need to use an unreliable kludge to attempt to correct SCSI timings post boot.

All you need to do is verify the correct 33C93A Config settings for your CLK speed and this is exactly what the new tool does!
 
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I assume I need GuruROM v6.16 that this works properly? I have 6.14 and get only 1mb/s.

20190112_115000.jpg
 
@maw2k

Your assumption is probably wrong. Also, you don't provide any details about the hardware config which provided the above results. So, your still quite a long way from making any better assumption(s). :picard
 
Some hardware details definitely needed. SCSI device model, accelerator (if any), SCSI controller (on accelerator or in a slot/sidecar, GVP or C=), etc. Some jumper settings on these units with a legacy ROM need changes for omniscsi.device. Also, if C=, was the 14Mhz mod done, and the jumper/DIP switch set?

If I were to take a real wild guess, that looks like an A2091 with a different SCSI device in a stock A2000 (or an A590/A500 combo) and both with some FastRAM. A 14Mhz clocking of the 33C93A is needed for the bus speed to take off, but the SCSI device also needs to have the matching media transfer speeds to take advantage of the faster SCSI bus.
 
I have the Gururom V6.16 in my A590. Dmac2, 14Mhz Hack.
Stock A500 REV6A, KS3.1 with 2MB in A590. SCSI IC = WD33C93A-PL 03. CF card Adapter Aztecmonster.
With 14Mhz hack, I get 2,553.350 Byte/sec (sysinfo). I think it's fine.

I tried to set the Synchronous mod but I do not see any difference.
For this, I set the 2 dip switches 1 and 2 on (up) on the A590. The 2nd switch should be the equivalent to Jumper 5 /4 from the A2091.
I put C:OmniScsiCtrl SYNCHRONOUS at the beginning of my startup-sequence.

Results with sysinfo is exactly the same as before, it does not makes any difference.

What am I doing wrong ?

Thanks

Edit :

33C93a tools tells,

Timout Reg = $17
Transfer Reg = $2C
 
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I don't know what is required to get an Aztec monster to function in synchronous mode. Hopefully, the documentation included does explain what is required.

You did not set the A590 DIP switch correctly, you should close DIP SW 1-3 for 14 MHz operation. The others should be set as indicated in the A590 FAQ. You also need to specify a UNIT number with Omniscsictrl unless you use RDBctrl to boot in sync mode (this is not recommended unless you are 100% certain the SCSI target device functions reliably in sync mode).

P.S. RSCP is a much better SCSI benchmark tool than Misinfo. ;)
 
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Unfortunately, there is nothing special about sync mod in Aztecmonster user guide.
As far as I know, some people have the Aztecmonster running sync on other Amiga scsi boards... Should be OK.

Just in case, I upgraded the A590 scsi chip with a -008.

I put the switches like this on my A590 : 1,2,3 up and 4 down. Close means up in the A590 FAQ if I understood well.

As in the GuruRom guide, I only put the device number. It's written "providing the address (TID) is sufficient"

The scsi device ID (Aztecmonster) is set to 0 per jumper.

I modified the the S-S : C:OmniScsiCtrl 0 SYNCHRONOUS

Sysinfo gives the same result as in my previous post. No differences.

Select timeout reg $2D
synch Transfer reg $2C

Are the registers as it should be ?

Thank you

I am using sysinfo for now just because I am connecting my A500+ test machine to a monitor through VGA adapter. Resolution used by RSCP is not good for this monitor......

EDIT :

I just connected the Amiga to a TV to give it a try with RSCP.

Strangely, sysinfo does not show differences between SYNC and ASYNC.

RSCP does, see pictures. First one in ASYNC and second with SYNC enable in s-s.
Sync is eating all the CPU ressource....

20190630_141305.jpg20190630_140643.jpg
 
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Any updates to this? I have performed the 14mhz mod, and noticed no issues so far.
 
Late to the party here. I have a couple of questions. First some details.

I have a 2000 with 2630 (And BigRam2630 which I have removed due to DMA issue). I have done the 14Mhz mode. I have 7.0 ROMS.

I am little fuzzy on what to do ROM wise. I am not sure how to use the config tool, nor what else I need to do to support this MOD. I do not think I have patched 7.0 ROMS so what should I do?

Secondly, with the BigRam installed on the 2630, my SCSI speeds crawl. I do have the AMD 08 Chip. I am using a SCSI2SD v5.1 and a ZIP drive on the chain. How can I get the 2091 to used DMA with the BigRAm installed? I do have 2 megs on the 2091.
 
Using a combination of A2091toFast and vbak2091 I was able to increase speeds (in SysInfo) from 100k to 1MB also keeping the 112mb of RAM on the BigRam2630. It’s not great but WAY better!

I am unsure if the 14mhz mod I did to the card is doing anything lol.
 
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I am unsure if the 14mhz mod I did to the card is doing anything lol.

It seems to do nothing. GadgetUK ran some tests before and after the mod in one of his recent videos and the speed difference/increase was........................ nil
 
Secondly, with the BigRam installed on the 2630, my SCSI speeds crawl. I do have the AMD 08 Chip. I am using a SCSI2SD v5.1 and a ZIP drive on the chain. How can I get the 2091 to used DMA with the BigRAm installed? I do have 2 megs on the 2091.

The A2091 can not DMA to Expansion RAM above the 24 Bit 16MB Area since a ZII Card has only 24 addresslines, so some Fastmen below this ist a must.
Best would be 2MB on de A2091, because the DMA can then be A2091 internal without utilize the ZII Bus, and the CPU only copy the data over the ZII Bus into high memory so throughput is something lower than the 3,5MB/sec ZII maximum ...

Since the original ROM has some Bugs with such configurationsans the A2091 should always equipped with a GURU Rom when memory above 16MB Area is present.
 
It seems to do nothing. GadgetUK ran some tests before and after the mod in one of his recent videos and the speed difference/increase was........................ nil

Then how did so many others get it to do something? GadgetUK's results must be just as bogus as the other "Nothings".

Since the original ROM has some Bugs with such configurations the A2091 should always equipped with a GURU Rom when memory above 16MB Area is present.

The Commodore v7.0 ROMs were mostly bug free but simply lacking the advanced features of the Guru ROM. Some of the obvious reasons why you didn't get a speed increase are:

1) You did the mod incorrectly
2) Your SCSI target device isn't fast enough to benefit from the mod
3) Your are using the Commodore ROMs and doing PIO transfers to memory above the 24BIT_DMA address space*
4) You are using the A2091 in an A3000/A4000 which significantly reduces it's performance
5) The benchmark program you chose gives bogus results :picard

*At least one of the "Nothings" read this thread and found the solution for this! (y)
 
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My issue of only getting 1MB was due to using an SCSI2SD v5.1. They max out at 1.1MB/sec. I have ordered a V6 so we will see if that improves it.

- - - Updated - - -

Also I am not having any luck finding GuruROM with the adapter for the A2091.
 
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