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Author Topic: DMA channels and Zorro slots  (Read 6110 times)

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Offline AmigaPixelTopic starter

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DMA channels and Zorro slots
« on: May 13, 2011, 09:59:26 AM »
It might be a dumb question, but as I am getting familiar again with the classic Amiga architecture, I have ask. Does the DMA bus controller in Agnus and Alice extend or allocate to the Zorro II and III slots when needed.
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Offline alexh

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Re: DMA channels and Zorro slots
« Reply #1 on: May 13, 2011, 02:19:11 PM »
AFAIK No.

It is outside the Agnus/Alice address range. The DMA masters in the Amiga chipset are AFAIK all limited to accessing Chip-RAM.
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Offline jj

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Re: DMA channels and Zorro slots
« Reply #2 on: May 13, 2011, 02:53:09 PM »
It thought though that the mediator used the memory on voodoo card to enable DMA on the other cards ?
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Offline mongo

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Re: DMA channels and Zorro slots
« Reply #3 on: May 13, 2011, 03:43:33 PM »
Quote from: JJ;637569
It thought though that the mediator used the memory on voodoo card to enable DMA on the other cards ?


The Mediator can't do DMA from a PCI card to the Amiga. It can do DMA from a PCI card to another PCI card, because this is handled by the PCI card and not the Mediator. So to use a card that requires DMA with a Mediator, you need a PCI card with memory on it for the other card to DMA to/from. Then you transfer from the memory on the PCI card to the Amiga by PIO.
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Offline jj

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Re: DMA channels and Zorro slots
« Reply #4 on: May 13, 2011, 03:57:45 PM »
got you
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Offline alexh

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Re: DMA channels and Zorro slots
« Reply #5 on: May 13, 2011, 04:00:32 PM »
Michael Boemer of E3B made a prototype firmware for Prometheus to add Zorro III DMA but I don't think it was ever released.
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Offline bloodline

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Re: DMA channels and Zorro slots
« Reply #6 on: May 13, 2011, 04:16:59 PM »
Zorro III had DMA? Was that mediated by buster?
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Offline Rodomoc

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Re: DMA channels and Zorro slots
« Reply #7 on: May 13, 2011, 05:06:38 PM »
1 DMA Zorro III device with Buster 11 only is what I remember.
Can an expert confirm?
 
Deneb USB card about the only thing out there that uses this ZIII DMA feature. Right?
« Last Edit: May 13, 2011, 05:08:54 PM by Rodomoc »
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Offline HammerD

Re: DMA channels and Zorro slots
« Reply #8 on: May 13, 2011, 05:39:33 PM »
Quote from: alexh;637583
Michael Boemer of E3B made a prototype firmware for Prometheus to add Zorro III DMA but I don't think it was ever released.


Actually it didn't add Zorro III DMA but working DMA capability between the PCI slots only.  Of course drivers would have to be adapted to take advantage of that.
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Offline HammerD

Re: DMA channels and Zorro slots
« Reply #9 on: May 13, 2011, 05:42:43 PM »
Quote from: Rodomoc;637595
1 DMA Zorro III device with Buster 11 only is what I remember.
Can an expert confirm?
 
Deneb USB card about the only thing out there that uses this ZIII DMA feature. Right?

Yes and a couple others.

Deneb, FastLane Z3, and the C= 4091 scsi card are all Zorro III DMA capable.  Maybe there are some others but I don't think so.

Rev 9 buster can theoretically handle more than one Zorro III DMA device, but there is a bug that happens if Zorro III memory is present.  Revision 11 buster has another bug which limits it to a single Zorro III DMA device. (Don't you just love C= bugs? :-/

The latest Deneb firmware (V11) works around these bugs, so with a Rev 9 buster you could theoretically have two Zorro III DMA devices.

I personally haven't tried it though as the only Zorro III DMA device I have is a Deneb.
« Last Edit: May 13, 2011, 05:45:31 PM by HammerD »
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Offline Rodomoc

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Re: DMA channels and Zorro slots
« Reply #10 on: May 13, 2011, 05:55:23 PM »
Thanks HammerD. And for the rev9 Buster info. I have little knowledge on the rev9 other than generally reported issues. My A3000 currently running a 7 Buster. I have an 11 but computer will not boot with it. Machine a native 25mhz and has Amiga Technologies vintage A3640 accelerator. I do not know if I need latest SDMAC or not. Would be cool to get this Buster 11 running.
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Offline freqmax

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Re: DMA channels and Zorro slots
« Reply #11 on: May 13, 2011, 06:48:03 PM »
Can the C= 4091 scsi card DMA to both fast and chip memory?, what's the situation for the various network cards? (commodore, X-Surf, Netsurf, Ariadne etc..)
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Offline Zac67

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Re: DMA channels and Zorro slots
« Reply #12 on: May 13, 2011, 10:11:02 PM »
There are several completely different kinds of DMA:
- chipset bus DMA - arbitrated by Agnus
- CPU bus DMA by Zorro II/III cards - arbitrated by (Super) Buster - since the CPU can access the chip bus this also includes chipset bus DMA
- CPU card DMA by onboard devices (=SCSI HBAs) - arbitrated by some onboard facility
- PCI busboard DMA is somewhat similar to the CPU card variant, but it seems to be very hard (impossible?) to DMA from PCI to Zorro, so it's from PCI to PCI only

A Z3 card is able to DMA to chipmem, but would be rather slow (you'd have to sync down to the chip bus plus wait for a chip DMA slot to come up). AFAIK there are no Zorro NICs that DMA.
« Last Edit: May 14, 2011, 10:01:41 AM by Zac67 »
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Offline freqmax

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Re: DMA channels and Zorro slots
« Reply #13 on: May 14, 2011, 12:05:00 AM »
Suprising that a soo much engineered computer uses that much PIO. And having a card with CPU+RAM+SCSI etc.. is essentially a computer on a card to circumvent the problem..
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Offline billt

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Re: DMA channels and Zorro slots
« Reply #14 on: May 14, 2011, 12:32:56 AM »
One possibility of this is to be a Buster replacement.

http://opencores.org/project,zorro_to_wishbone_bridge
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