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pci 2 zorro bridge
by Ratte on Jan 21, 2010
Posts: 1
Joined: Jan 20, 2010
Last seen: Jan 21, 2010
first I am a newbie and i KNOW it will be a very long and hard way to learn and to understand.
So please dont ignore my questitions, I need some (moral) support.

My target will be a connection between two computersystems.
One the one side there will be a PC and on the other side my beloved classic-system Amiga.
We dont need to talk about the sense of classic computing ... its a hobby :-)

I would like to upgrade my old system with some GHZ power, i stand in contact to some softwaredevelopers like Toni Wilen who is responsible for the x86 Amiga Emulator "WinUAE".
He promised me software support in kind of a raw 68k-emulation on a PC that is communicating with "real" amiga-hardware over a "has to be done" pci-bridge.

So the target will be a pci to zorro (amiga bus) bridge.
There are a lot of pci-bridges allready in the projects, but is the some kind of pci-bridge that is suitable with less modifications?

One the one side there is the multiplexed pci-bus and on the other side is the amiga-bus with separated adress and databus.
Some bus protocols must be generated and interruptssignals must be passed trough to the pc.

At the end there will be some kind of x86-68k emulating processorboard (pico-itx) for the amiga.

How realistic is the idea?
Is there some existing pci-bridge that is predestined for such a project?
What kind of FPGA would you use for such a project.
(5V tolerant would make things a lot easier)
How many years should i calculate ...
(Only some skills in electronics and SMD-soldering 0,6 pitch)

Thanks in advance
Andre "Ratte" Pfeiffer
Bielefeld, Germany
bridge.pdf (466 kb)
RE: pci 2 zorro bridge
by amigabill on Jan 22, 2010
Posts: 34
Joined: Dec 14, 2008
Last seen: Oct 13, 2013
What I'd do is a Wishbone/Zorro bridge at this point. I believe one of the PCI bridges goes to wishbone, then you can connect the two wishbone ends together. Maybe not the optimal way if you only want PCI to Zorro, but makes the Zorro bridge more versatile if someone else wants to use it for some reason. Otherwise, look at the Wishbone side of the PCI bridge and make it look like Zorro instead. But go for a Wishbone bridge...

I don't understand the picoITX part. Is this a PC that fits into an Amiga Zorro slot? If so, why not use a PCI card format x86 card instead with a Mediator or Prometheus bridge card to PCI slot? Curious about why you chose the PicoITX format.

I'd also be interested in a PCI target to Amiga CPU slot bridge. What about using the x86 as a 68k emulating accelerator card there?

If you hadn't mentioned PicoITX, I'd be thinking you want to plug Zorro cards into a PC motherboard's PCI slot. That's would be a little awkward in the case since most Zorro cards are so big (full-size ISA dimensions I believe).

The 5V tolerance is not required in the FPGA itself, you can use level shifters (voltage translators) outside the FPGA, but that is additional chips and board space.

I've wanted to do a PCI/Zorro bridge but am myself learning some of that. More for an "add PCI slots to my Amiga" application. I'm not yet the RTL or PCB expert you need, but am interested and can help with ideas if needed. I am now learning Eagle PCB tough.
RE: pci 2 zorro bridge
by amigabill on Mar 31, 2011
Posts: 34
Joined: Dec 14, 2008
Last seen: Oct 13, 2013
I don't remember looking at your diagram when you first posted this. Considering you're intending to connect to the 86pin side expansion of an A1000, you don't seem to need the full 100pin Zorro2 slot stuff with the Buster chip logic involved, I think you're going right onto the 68000 CPU bus there. I'd suggest looking at the 68000 bus to Wishbone bridge here on opencores, and mating that with a suitable PCI to Wishbone bridge here. I'd wager that PCI target is enough for what this seems to be, not needing PCI Master. The exists 68K/Wishbone master bridge seems to be to put a Wishbone bus onto a 68K CPU, which is backwards from what I think you want, but may work that way or may not be too hard to turn into what you seem to want, which is a Wishbone slave to 68000 socket.

x86 PC Computer -> [PCI Target -> Wishbone] -> [Wishbone -> 68000/Dragonball] -> A1000 side slot,wbif_68k,pci,pci_mini,pci32tlite_oc

Was any progress with this ever made? The German forum thread you linked to seems to have ended back in Nov 2008 and didn't really talk about this bridge anyway. I'm curious to hear about this.
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