Deneb USB PIO vs DMA

[videofx]

Does anyone have any benchmarks on the 2 xfer modes of the Deneb? PIO vs DMA?

Thanks

[alexh]

Using which accelerator?

[videofx]

Blizzard 1260

[jack-3d]

B1260? Then it looks like you have it in Zorro2, right? Deneb in Zorro2 can use only Z2 mode (must be even switched with jumper on the board).

[fitzsteve]

Transfer speed is the same but overall system performance is better in DMA mode as USB instructions are done in FPGA so less CPU overhead.

You can read about it here:

http://www.e3b.de/usb/main_faq_e.html#DENEB_PIO_DMA

[videofx]

What about if I put it in my 4000T with Cyberstorm PPC

I am using the internal scsi so according to Deneb cant use DMA so I am looking at wether its worth it to do scsi on the cyberstorm for DMA or is PIO fast enough.

[fitzsteve]

Originally Posted by videofx

What about if I put it in my 4000T with Cyberstorm PPC

I am using the internal scsi so according to Deneb cant use DMA so I am looking at wether its worth it to do scsi on the cyberstorm for DMA or is PIO fast enough.

PIO is fast enough with 060 so don't worry, you are right A4000T SCSI is DMA Busmaster so you can't use Deneb in DMA mode with your A4000T.

There is a work around, Buster -9 allows multiple BusMasters, I successfully used a Deneb in DMA with Fastlane Z3 (also DMA BusMaster) but it means changing Buster (maybe soldered in A4000T) and -9 has issues with some cards so maybe cause you more trouble in the end.

But anyway, with 060 you will be fine in PIO.

[videofx]

Thanks, Here is the answer

A4000/060 PIO A4000/060 DMA
8GB USB2 Stick 4915 kB/s 6336 kB/s
USB2Sata 160GB 4928 kB/s 6361 kB/s

[alexh]

Originally Posted by videofx

I am looking at wether its worth it to do scsi on the cyberstorm for DMA or is PIO fast enough.

You would be crazy not to. The Cyberstorm SCSI is many many times faster than the A4000T SCSI!

Add to that the lowered CPU overhead of Deneb in DMA mode and if you are right improved data rates

[ancalimon]

Originally Posted by alexh

You would be crazy not to. The Cyberstorm SCSI is many many times faster than the A4000T SCSI!

Add to that the lowered CPU overhead of Deneb in DMA mode and if you are right improved data rates

As far as I remember, I was getting either 25mbps or 35mbps on the CStormPPC's scsi3 (using an Acard SCSIDE bridge). Back in the day, it was faster than any PC I have seen

[alexh]

Yes a fast UltraWide SCSI HDD or an Acard AEC-7720UW + fast IDE drive could do 25Mbyte/s and higher with a Cyberstorm PPC

[ancalimon]

So do you think I should remove the scsi2 cdwriter from 4000t scsi port and plug it to the Cyberstorm? (I got a basic converter). Would that effect performance?

[alexh]

Ah, you've already got a HDD on your Cyberstorm and you attach your ODD to the A4000T SCSI port.

Well I think you are correct. I believe that having a narrow SCSI2 ODD in your UltraWide SCSI chain on the Cyberstorm will slow down all the devices on the chain.

But I do not know for sure and I've never tested it as my Cyberstorm MKIII is broken.

Why not ditch your CD writer now you've got a Deneb?

[ancalimon]

Originally Posted by alexh

Ah, you've already got a HDD on your Cyberstorm and you attach your ODD to the A4000T SCSI port.

Well I think you are correct. I believe that having a narrow SCSI2 ODD in your UltraWide SCSI chain on the Cyberstorm will slow down all the devices on the chain.

But I do not know for sure and I've never tested it as my Cyberstorm MKIII is broken.

Why not ditch your CD writer now you've got a Deneb?

Videofx got a Deneb. I do not My 4000T will arrive in a week (it's finally being repaired). I will install OS4.1 on it and I've read that 4000T onboard scsi2 is not supported. I guess I can plug in an IDE CDROM instead of moving the cdwriter to CybersotormPPC scsi3.

[videofx]

Are you saying I can take my CD off the internal 4000T SCSI and use a USB CDrom? Is that supported in 3.1 with ASIMCDFS? How do I do I do it?

[ancalimon]

Originally Posted by videofx

Are you saying I can take my CD off the internal 4000T SCSI and use a USB CDrom? Is that supported in 3.1 with ASIMCDFS? How do I do I do it?

Not a usb. A normal IDE CDROM.

[jack-3d]

Originally Posted by videofx

Are you saying I can take my CD off the internal 4000T SCSI and use a USB CDrom? Is that supported in 3.1 with ASIMCDFS? How do I do I do it?

Not sure with AsimCDFS, but why not. I use Idefix97 and his filesystem. But YES absolutely use USB DCROM! With DENEB I could finally get rid of my DVDROM out of the A4000 desktop and I use external slim DVD just when I need it.

You simply attach it to USB port, check with Poseidon it is detected. Then you install Idefix97 that detects your optical drive on cdromusb.device or something like that (cannot check now). Idefix97 will make mounter and you are done.

I mount DVDROM only when I need, so I have mounting icon on Workbench ready.