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Thanks for your answer. Anyway, let's say that my two devices accept pio mode 4 (a hdd capable to run up to udma mode 4 and a dvd player capable to run up to pio mode 4), so the max speed for pio mode. (this is normally the case for all device present in the market). Because the commands are sent in pio timings (mode 4 in this case), I think that I can communicate in udma mode 4 with the hdd, and pio mode 4 with the dvd player. Do you agree that the read and write with the hdd will not perturb the dvd player ? Same question when I use the same hdd, plus another hdd capable to run up to mode 2 instead of a dvd player. Rgds, S. [EMAIL PROTECTED] wrote: > This message is from the T13 list server. > > On Mon, 07 Oct 2002 09:25:08 +0200, Stephane Cattaneo wrote: > >This message is from the T13 list server. > >Regarding when you have two devices, with two different speeds, can I > >use the fastest speed of the two to communicate with both of them ? > and > >I mean communicate with each max speed for each device. (and not use the > >slowest speed to communicate with both of them) It lookslike it works, > >but I want a confirmation by the specialist.... > > The answer to your question is found in Note 5 in the "Register > transfer to/from device" table. In one word the answer is "NO". > > My question would be: Why do you think you can violate the PIO timing > of the slower device on the interface and still expect that device to > respond correctly to writes to the registers? Think about what > happens if the slower device, while not selected, fails to see a Soft > Reset or a change in the DEV bit value. > > *** Hale Landis *** www.ata-atapi.com ***
