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Excerp from Pat LaVarre, 1/15/02: >.... >I wish somebody would go take a port to Mac OS X of the traditional Cizer >tool and try http://members.aol.com/plscsi/20020328/oddwinme.txt >and see if you don't see 6 bytes copied In when the device said to copy >In 5, for a Cdb like -x 12 0 0 0 05 0. Ouch. > > .... Pat, The device is SUPPOSED to transfer in 6 bytes if the host requests 5. It beats the alternative of transfering in only 4 bytes when the host requests 5. However, I admit there is a potential for the device to "do it wrong" so the host CAN resolve the ambiguity by requesting an EVEN byte count for the variable length stuff and providing adequate buffer for the "extra byte". In spite of what your software analyzer seems to show, I think you will find that the actual data words transferred accross the ATA bus are IDENTICAL for the two devices. They both MUST transfer 3 DATA words accross the bus -- independent of whether it is PIO, SWDMA, MWDMA, or UDMA. If there is actually a differance at the application level then it must be due to the operating system double buffering the Inquiry command in one case, and not in the other. ...Harlan
