seamus@bucsf.bu.edu (Jeff Rizzo) (02/10/91)
I realize that this is probably an extremely stupid question in ways that I can't even comprehend right now, but here goes anyway. What exactly are the differences between the Zorro II bus on the Amiga 2000 and the expansion connector on the 500? Besides obvious physical differences, what additional signals are provided in the 2000? I have very little access to technical dox on either machine, not to mention very little money with which to purchase any, so net.replies are most welcome... Thanks, folks... jeff -- ------------------------------------------------------------------------------- Jeff Rizzo INTERNET: seamus@bucsf.bu.edu OR phyq8jc@BUACCA.BITNET Boston University BIX: jrizzo CLA '91 ping! (617)566-0693
daveh@cbmvax.commodore.com (Dave Haynie) (02/15/91)
In article <SEAMUS.91Feb9232804@bucsf.bu.edu> seamus@bucsf.bu.edu (Jeff Rizzo) writes: >What exactly are the differences between the Zorro II bus on the Amiga 2000 >and the expansion connector on the 500? Well, first off, the Zorro II bus, while based on same signals available at the edge of an A500 or A2000, is designed to handle multiple devices. For this to work properly, there is full support for the Autoconfig "chain" from one card to the next, support for arbitrated BR* and BG* for each slot (the BR*/BG* at the A500 connector is tied directly to the 68000), support for collision detection between multiple Zorro II cards (so a trojan horse program can't come along, configure all your boards to the same address, and then read from them all, causing destructive buffer fights), etc. And of course, the bus is buffered as well, so that multiple cards can run on it without dragging down each other or the main CPU. On top of that, there are additional useful lines. Zorro II has +5V, -5V, +12V, and -12V supplies available. It has the 7MHz clock in addition to C1*, C3*, and CDAC available at the A500 edge. It has the DOE signal which can be used to determine when buffers get turned on during a read cycle. It has a GBG*, a "global bus grant" signal, which a DMA card can monitor to determine if other cards are waiting for the bus. And it has additional grounding, to help keep noise down on the bus. There are a few other differences, but these are the main ones. >I have very little access to technical dox on either machine, The "A500/A2000 Technical Reference Manual", which describes the expansion bus, is available from Commodore. I don't have the price offhand, but the info is posted on the net every so often. That book, and a 68000 manual, is enough to design a Zorro II or A500 expansion device. If you're just curious, you can probably get any questions answered here. >jeff -- Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy "What works for me might work for you" -Jimmy Buffett
allen@grebyn.com (Allen Farrington) (02/16/91)
In article <18961@cbmvax.commodore.com>, daveh@cbmvax.commodore.com (Dave Haynie) writes: > The "A500/A2000 Technical Reference Manual"...is available from Commodore. > -- > Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests" Do you have to be registered as a Certified Developer to obtain this Reference? --Allen |------------------------------------------| | Allen H. Farrington (703) 222-9612 | "It's like nothing we've ever | allen@grebyn.com | dealt with before." |------------------------------------------| -Mr. Spock -- |------------------------------------------| | Allen H. Farrington (703) 222-9612 | "It's like nothing we've ever | allen@grebyn.com | dealt with before." |------------------------------------------| -Mr. Spock