A4091 info

[JuvUK]

Hi All,
I'm after info on the A4091, i've googled it and read the big book and resource sites, but i'm after real world user reviews.
it says it has a theoretical 10mb/s transfer speed, what is the real speed? i'm guessing 4/5mb?

and finally, what sort of price do these go for?

cheers, JuvUK

[alexh]

They are not particularly sought after these days because people want either an accelerator with SCSI or the Phase5 Fastlane because they are also a Fast RAM upgrade. Plus SCSI disks are expensive. I imagine somewhere around the £30-50 mark.

http://cgi.ebay.co.uk/ws/eBayISAPI.d...m=320559951388

I'm sure you know these are usable in the A3000(T) & A4000D only?

Do you have, or are you planning to get a Deneb USB controller?

A4091 is a Zorro III DMA Master. Buster Rev 11 only supports one Zorro III DMA master. So you won't be able to a Deneb USB Host (in DMA mode) at the same time.

Also a Deneb with a good USB hard drive is probably faster.

[JuvUK]

Originally Posted by alexh

They are not particularly sought after these days because people want either an accelerator with SCSI or the Phase5 Fastlane because they are also a Fast RAM upgrade. Plus SCSI disks are expensive. I imagine somewhere around the £30-50 mark.

http://cgi.ebay.co.uk/ws/eBayISAPI.d...m=320559951388

I'm sure you know these are usable in the A3000(T) & A4000D only?

Do you have, or are you planning to get a Deneb USB controller?

A4091 is a Zorro III DMA Master. Buster Rev 11 only supports one Zorro III DMA master. So you won't be able to a Deneb USB Host (in DMA mode) at the same time.

Also a Deneb with a good USB hard drive is probably faster.

i have a A4K with buster 11, no desire to get a Deneb (no interest in it either)
so what speed realistically will the A4091 run at?

[Toni Wilen]

Blizzard SCSI expansion (10M SCSI-2) real world max is about 5-7M/s (uses similar NCR/Symbios SCSI chip) when connected to SCSI-IDE adapter and fast CF card. I think all DMA SCSI adapters can handle 5M/s or more when transferring to/from 32-bit fast ram (I mean fast ram that is 68020+ friendly)

[JuvUK]

thanks guys

if i can get 5mb/s ish from this then i will be a happy boy

[zipper]

I got 7-8 MB/s from Blizzard 2060 at best, probably a similar design, too.

[alexh]

Originally Posted by zipper

Blizzard 2060 probably a similar design, too.

Seems unlikely. Does the SCSI card appear in the Zorro III space? Or the CPU space?

[Jope]

CPU space, and it transfers to the onboard RAM.

[alexh]

Sounds like it is potentially faster than an A4091 SCSI controller then. At the very least speed comparisons between the two are not practical.

[reinauer]

SCSI attached to an accelerator will always be faster than anything that goes over Zorro III (or even II).

Ihr you are willing to exchange some GALs on your A4091 you might get an extra megabyte per second compared to the original logic. YMMV. Depends on the Amiga (3000 v 4000), accelerator used, memory in the system, etc. Generally transfers into Zorro III memory are much faster than into CPU memory or mainboard memory, but then you pay later trying to operate on that data. So it's hard to talk about one absolute speed here. Without overclocking and with the new 4091 GALs we've seen 5.8M/s to mainboard memory and 8.5mb/s to Zorro III. At 66MHz with a Zulu 2040 into Zorro III we have measured 9.6 to 9.8MB/s(!). This overclocks the SCSI bus and at this point it also depends on the SD card used in the Zulu 2040.