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> Harlan Andrews <[EMAIL PROTECTED]> > these questions ... > about Device0/Device1 (Master/Slave) detection and operation. > I've trouble finding them in the spec. I think the printed answers were as follows in Ata/pi 4. I'm posting quickly in the hope of a free, good, quick education on how wrong I am about Ata/pi 4 and how much more wrong Ata/pi 7 makes me. (I hear the real answers are in some dispute, especially when people are working to minimise boot/reset delays. But I trust we all want to begin the discussion by establishing consensus over what the printed answers are.) > 1. Is there a spec on how long the Device1 should assert DASP ? > I.E. Is there a minimum assertion time for DASP ? Device0 should wait 750ms after a reset that requires DASP- before giving up on seeing DASP- ... so Device1 had better get it asserted by then. In the printed text, how agreed Device0 and Device1 are about when a power-on reset begins used to be fuzzy. Device1 should keep DASP- asserted lo until told to release it: by a write of x1F7 Command when Device1 is not BSY and is selected by DEV, or by the expiry of a specified timeout (30-ish seconds for most resets). Some Windows Oem's require that Device1 also release DASP- when a command is written to Device0, to turn off the HDD light between when the Bios hands control to Windows and when Windows gets around to talking to Device1. > 2. Is there a spec on how long or how often > Device0 should check DASP to determine > if a Device1 is present ? > Is DASP allowed to move after initial handshake? Grin. Excellent question. No spec. Rumour says plug 'n pray goes better if Device0 is a little slow to believe DASP- is lo. Some people think Best Practice demands a debounce like at least two samples in a row that agree. > 3. What is the reason for the 1 MS max spec > on releasing PDIAG after RESET ? > 4. What would be the consequences > of being late releasing PDIAG after RESET ? PDIAG- could not then be easily used for other things, like 80 pin cable detection, in which PDIAG- is helpfully named CBLID-. > 5. Does method of determining > Device0 vs Device1 have ANY effect > upon the requirements for DASP and PDIAG ? Not specified. > I.E. Is JumperSelect same as CableSelect > with respect to DASP and PDIAG ? Not specified. Often true. Lately the once-reserved "word 93" of the op xEC/A1 Identify device has been given meaning to report if the device knows whether it was jumper-selected or cable-selected. > I'm posting quickly in the hope of a free, good, quick education Let the games begin. Pat LaVarre Subscribe/Unsubscribe instructions can be found at www.t13.org.
