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SCSI RESELECTION PHASE DETECTOR

IP.com Disclosure Number: IPCOM000035057D
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-28

Publishing Venue

IBM

Related People

Authors:
Christianson, MD [+details]

Abstract

The SCSI (Small Computer System Interface) specification requires that a target on the SCSI bus, which is trying to reselect an initiator, arbitrate and win control of the bus before entering the Reselection Phase. Once in the Reselection Phase, the target will release busy after having activated select, I/O and the initiator's ID bit on the data bus. The initiator is to detect this condition for at least 400 ns before responding to the target by activating busy. (Image Omitted) The Reselection Phase will begin with the device, already driving select and I/O true, driving the initiator's ID bit and its own ID bit on the data bus at least 90 ns before it releases busy (1 - see Fig. 1). The initiator must determine if it is the intended target of the reselection attempt by detecting its ID bit active on the data bus.