CompuServe Messages

Not exactly, zorro3 only needs to dma into other zorro slots or chip ram. chip ram doesn't need 32bit addressing as it is only ever the first 2mb of ram. It probably wouldn't be able to dma to the pcmcia, but again that doesn't need 32bit addressing. The zorro3 bus could internally dma to other cards without getting anyware near the trapdoor slot. The design goal for zorro3 was that it could be interphased to any processor and dmaing between zorro cards is not seen on the chip bus. If you read the zorro3 section of the hardware reference manual you would get a better understanding. Basically a zorro2 implementation uses the raw signals of the trapdoor port whereas zorro3 handles most of the processing itself and only passes on what it can't handle (like dmaing to chip memory). You don't need a 32bit cpu for zorro3 as there was a prototype 020ec machine with a zorro3 bus in it ( I think some of them were sold off as part of the auction process ). Zorro3 would be expensive to add to an a1200, but not impossible. If you have any contradictory evidence I would be interested, but don't beleive sales hype. If someone has a zorro2 tower on sale and you say "well I would buy one if it was zorro3" then they will tell you it is impossible. What they mean is that they haven't done it yet and they wouldn't be able to make enough money on it. If you could buy a buster chip the rest would probably be very easy, but you can't buy them in big enough quantities and re-designing it would be a pig. Actually this reminds me of my idea for a pcmcia video board, everyone says this is impossible too. I wish I had the money to invest in developing one. Phill