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> [EMAIL PROTECTED] 12/17/01 10:32AM > > Let's try the example Scsi Cdb of x 2A 0 00:00:00:00 0 00:12 0 > > i.e. a write of the x12 blocks at Lba 0. > > But now let's suppose the Bad Media refuses to let the device > > move more than 3 blocks. And let's suppose our device, in > > Pio/SwDmw/MwDma modes, accordingly moves just 4 * x200 = x800 > > bytes and then stops the transfer. > [EMAIL PROTECTED] 12/17/01 10:32AM > Do you mean "pause" or "stop" This time when I said stop I meant stop. Again I'm sorry that two weeks ago, til the famous phone call that clued me in, I wasn't clear on that distinction. My original source who told me of hard drives that do send more bytes than expected isn't clear on whether the host decided the bytes in were unexpected because a faster UDma burst rate allows more or because, say, the device clocked more than 4 * x200 = x800 bytes in for a 4 block read. My original source says the latter, but talk here is leading me to disbelieve. > I meant stop. Let me elaborate: In Pio, the next INTRQ would arrive with BSY:DRQ = 0:0 rather than 0:1. The C/D I/O would be x03 StatusIn, not x00 DataOut. In Pio, the device, the receiver of clocks, would have stopped the sender on a byte. In Pio, merely by observing the bus trace from after the command block til before status, all could agree how many bytes of data were exchanged. > I meant stop. SwDma/MwDma I don't know well. I gather to stop the host after an arbitrarily chosen two byte "word", there the device can deassert DMARQ, soon enough after the last DIOR/DIOW that the host cooperatively avoids sending another DIOR/DIOW clock. Pat LaVarre Subscribe/Unsubscribe instructions can be found at www.t13.org.
