Classic IDE DMA possible?

[SHADES]

Hi all,

I'm looking at the Zorro 3 specs and to me it looks like there is the ability to do DMA access of up to 50 MB/s non burst.

Is there some other reason as to why no one want's to manufacture a DMA IDE interface? One of the DMA modes for IDE is ATA33 which is well within the DMA spec.

I believe the AMIGA 3000 is limited to about 20 MB/sec due to a slower clock speed, the faster AMIGAs should be able to handle it though.

[SHADES]

Hmm, 20 MB/sec on A3000 was acuivable with a slower clock, ATA33 seems to me not an impossible target to achieve. A faster external clock could drive it. Doesn't a4000 have that ability?? Didn't know that burst modes didn't work! I was sure my Fastlane Z3 did burst and it can sustain 11MB/sec no problem. I know the hypermemory card used burst modes.www.amiga-hardware.com Now i'm thinking, I haven't seen any 100Mbit ethernet cards. I wonder why burst isn't working! Time to visit Haynie's page. About being worth while, you're probably correct there. Most H/w is failing now. I'm about to try fix my 4000 again which is grey screening and not booting. I have 3 cpu cards and 3 mainboards to try scavenge parts from. Hoping one is still able to function.

[SHADES]

"how much units do you think you could sell ?"

This is a very valid point. I thoiught with todays mass chip manufacture, things like DMA IDE chips would be cheap, but then there's logic to Zorro 3 which may not be so that makes sense. Still they produce IDE cards that don't do DMA still, then again, there's much less logic needed to do PIO modes.

I'd say you are very correct here. Most mainboards are dying, why bother. I wonder if IDE cards on the Mediator would work properly

[SHADES]

"Burst mode on Zorro III (using /MTACK and /MTCR) does not really work. If it worked you could do one Zorro III cycle and access 64 longwords, doing only one Zorro III address phase and 64 data phases."

Is this a Buster 11 fault? from the looks of the specs, everything is set out quite nicely.
Haynie link to burst I also found this which was instruction on how to implement the zorro3 spec properly. Zorro 3 design How to design zorro 3 card. Looks like the use of /FCS is how to get in to the burst cycle.
I haven't seen anythuing on buster 11 yet, if it is a buster problem, I'm still looking. I guess it's irreleveant now, Zorro III is ancient compared to PCI express.

The mind really boggals with the what IFs on what hardware would be like now if Ami H/W was successful in market penetration, such a shame