CD-ROM SCSI-2 COMMAND REFERENCE MANUAL VERSION 3.1 (OB-U0077C)

1.3SCSI Protocol

The SCSI Protocol outlined in this section applies only to SCSI bus models. It does not support ATA bus models.

1.3.1Command Link/Control Field

The Control Field inside the Command Block is defined as:

Bit

7

6

5

4

3

2

1

0

 

Vendor Unique

 

Reserved

 

Flag

Link

The Command Link function is not supported by the DRM/DR-U Series. Set Flag and Link bits to “0” (FALSE).

Set the RelAdr (Relative Address) bit, bit 0 of byte 1, inside the Command Block to “0” (FALSE).

1.3.2Disconnect/Reselect

Selection time-out period is 250 ms.

If the initiator does not respond to reselection within the time-out period, the drive will release the bus for a minimum of 200 ms. The drive will then repeat the arbitration/reselection sequence until the initiator responds, issues BUS DEVICE RESET, or until the SCSI bus is reset. During a reselection retry, the drive will return BUSY to selection requests from any initiator.

During execution of audio commands, if the disconnect/reselect function is selected, the drive disconnects from the initiator before execution a SEEK or other operation that requires head movement. When the selected address is located, the drive reselects the initiator and begins audio playback. The time needed for the reselection procedure is dependent upon the status of the SCSI bus. Audio playback may begin before the reselection is complete. Refer to Appendix A for more information.

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