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>>> McGrath, Jim 03/20/02 06:55PM >>> Help, I'm lost here, in my stunning ignorance of Ata ... > Later people started using SEEK > as a poor man's attempt to overlap commands Yes. > (since SEEK actually completes immediately, > allowing the ATA bus to be freed for use > by a second drive while the first is still seeking). Ansi T13 never published this fact anywhere, did it? > time to obsolete SEEK (in my opinion) > in favor of the 5 year "new" overlap command > capability that was designed to obsolete it. Do Ata drives actually now commonly implement overlapped commands? Anybody shipping host software to run on the desktop (Apple Mac, Microsoft Windows, Linux) that actually issue overlapped commands to recover Ide bus bandwidth? I hear Atapi devices commonly do Not implement overlapped commands, and that Microsoft Windows includes an remarkably poor implementation for discovering when the bus is again usable. They send a Scsi (aka Atapi) op x2B SeekImmediate before any Read/Write to an Atapi Slave of an Ata Master, no matter if the Ata Master is in use or not. Then they then poll x3F6 AlternateStatus & x11 (DSC|ERR) on a 19.2 Hz clock ... In effect, they add 2/19.2 = 26ms to every Seek. (Unless you install third-party proprietary modifications to Microsoft Windows that fix all this.) Anybody know better? Thanks in advance. x4402 Pat LaVarre [EMAIL PROTECTED] http://members.aol.com/plscsi/
