Which is the better scsi card for the A4000?

[tone007]

No.

Well, only to ZII memory.

[alexh]

Well, only to ZII memory.

Yes I think this is true. A GVP controller with RAM for example has DMA. You must use the memory mask fields in the RDB to constrict the memory the SCSI driver will use.

Obviously this RAM is 16-bit and has a bandwidth limitation when used by a 32-bit CPU.

Some accelerators have their own 32-bit CPU, 32-bit RAM, SCSI controller and DMA controller to overcome these problems. (Cyberstorm for example.)

[jj]

I knew that the blizzard with scsi did DMA , and I figured that Zorro II didnt as I have never seen anyhting for Zorro II that did , well not Zorro II on my A1200 anyway.

[Motormouth]

Basically DMA called is direct memory access can as it sounds can make transfers directly to memory.  PIO mode stands for programmed I/O requires the CPU to get involved, taking CPU cycles.  The problem with many zorro II DMA cards is they can only "DMA" to 16bit memory on a A3000 or A4000 the 32bit memory is at a different location.  Some zorro II cards can DMA to 32 bit memory in an a3000 or a4000 but the transfer is only 16bit and can slow things down in other ways.

I have a habit having some 16bit fast ram, 2megs or  more, in my a2000s and a500s even if I have a 32bit accelerator cards.  This aids in DMA transfers on their respective the 16 bit buses.  On A3000s or a4000s it is a bit of different story.

The A4091 is a zorro III card and can used the 32 bit bus.

I am still a little confused at how and when the Amiga made use of PIO versus DMA, specifically with SCSI and IDE configurations. I remember it was always a big deal that the Amiga had DMA channels

[AmigaPixel]

@alexh

OK thanks for clearing that up. Is Gayle the IDE controller in AGA machines?

[AmigaPixel]

Yes I think this is true. A GVP controller with RAM for example has DMA. You must use the memory mask fields in the RDB to constrict the memory the SCSI driver will use.

Obviously this RAM is 16-bit and has a bandwidth limitation when used by a 32-bit CPU.

Some accelerators have their own 32-bit CPU, 32-bit RAM, SCSI controller and DMA controller to overcome these problems. (Cyberstorm for example.)

I had a Phase 5 Blizzard 060 and SCSI II controller in my A1200, I wonder if controller was 32bit with DMA? I don't remember the specs. The SCSI board also supported 72 pin SIMMs like the 060 accelerator.

[psxphill]

I had a Phase 5 Blizzard 060 and SCSI II controller in my A1200, I wonder if controller was 32bit with DMA? I don't remember the specs. The SCSI board also supported 72 pin SIMMs like the 060 accelerator.

The ram was 32bit & supported dma. You wouldn't need to have a simm on the blizzard scsi board, it's just for extra ram expansion. But you would at least need some ram on the accelerator.

[AmigaPixel]

The ram was 32bit & supported dma. You wouldn't need to have a simm on the blizzard scsi board, it's just for extra ram expansion. But you would at least need some ram on the accelerator.

Actually I think it was the Blizzard IV SCSI II controller, which according to "The Big Book of Amiga Hardware" was a 32 bit DMA able. At the time I had a 16MB SIMM on the accelerator and 4MB SIMM on the SCSI. That little 060 ran hot, I use to take the trap door off and raise it up about 1/2 inch for better air flow. I then aimed a house fan on the A1200 when I was rendering 3D animations. I sometimes wished I hadn't sold all of it.

[AndyLandy]

In order of preference:

• SCSI controller on your accelerator card.
• Zorro III DMA SCSI controller (A4091 or FastLane Z3)
• Zorro II DMA SCSI controller with some Z2 FastRAM (GVP HC+8/Oktagon 2008 etc)
• On-board IDE.
• Zorro II polled IO SCSI controller.

If you have a sufficiently awesome CPU card, you might prefer the on-board IDE to the Z2 DMA solution, but then again, any CPU card that's good enough probably has a SCSI option anyway.

[alexh]

Is Gayle the IDE controller in AGA machines?

And in the A600, on the Viper A530 Turbo card, and re-created in the IDE68k addon.

[Nearly-Right]

I knew that the blizzard with scsi did DMA , and I figured that Zorro II didnt as I have never seen anyhting for Zorro II that did , well not Zorro II on my A1200 anyway.

I have a Mediator card in my A1200, and my A4000. I just had an update from Darren Stevens for his device driver for certain PCI Adaptec SCSI cards, which now works for me with my Epson GT scanner, and as I have SCSI cards already in my A1200, and A4000, one on the accelerator, and one as an additional SCSI card, it offers me an additional 7 SCSI devices I can attach to each of my systems. With the Elbox Mediator pci.libabry RAM advantage of adding about 250MB of RAM from my PCI 9200 256MB Radeon GFX card onto my A1200 system FastRAM I've got close to 1/2GB of RAM, oh yes that's right almost HALF A GIGABYTE of RAM on a Classic Amiga.

[mechy]

And in the A600, on the Viper A530 Turbo card, and re-created in the IDE68k addon.

and the viper520cd

[freqmax]

Nearly-Right, Maybe you could exploit the RAM on the other computers by using it as an RAM-disc over SCSI by using the SCSI-bus ?