This message is from the T13 list server.
Sorry, I tried to reply directly to this question but the email address doesn't work... Maybe the person asking this question has some other email addresss that receives the T13 list messages? On Sat, 21 Aug 2004 22:03:19 -0700, Lolo wrote: >This message is from the T13 list server. >Question about using the DEV bit in the Device register. The spec says >device register indeterminant if written to when DRQ or BSY bit is 1. What >about for overlap commands when the DEV bit in the Device register needed to >be changed while DRQ or BSY can be asserted? Writing to any Command Block register is always "illegal" if BSY=1 or BSY=0 DRQ=1. Also note that there is no time in the Overlap/Queued command protocols when the host changes the DEV bit except when the currently selected device has status of BSY=0 and DRQ=0. The SERV bit is used by the host to know when a device wants "service": A device that has "released" has status of BSY=0 DRQ=0 and must turn on the SERV bit to signal the host that its wants "service". Hale *** Hale Landis *** www.ata-atapi.com ***
