Ciprico Rimfire 3880 manual Board-control Commands Extended Unit Options 18H Unit Flags

Chapter 7 Board-control Commands

Page 7 - 48 Extended Unit Options (18H)

Unit Flags

Note

If you set the TAG flag (explained on next page) the adapter will ignore the UNQ bit. Setting the TAG bit implies that you are using a SCSI-2 or SCSI-3 device. The UNQ bit is intended for SCSI-1 devices.

The Unit Flags field of the Extended Unit Options Parameter Block is where you can define command operation for the unit. With bit settings you can address the issues of: synchronous data transfer, tagged commands, and use of ATN signal.

BITS

7	6	5	4	3	2	1	0
0	TAG	0	0	WID	IAT	SYN	UNQ

Table 106: Unit Flags of Extended Unit Options

UNQ Untagged Queuing - The SCSI-1 specification allows issue of multiple, simultaneous, commands to a target that has multiple LUN’s, one command per LUN. This bit allows you to select whether the RF3880 will queue commands to a target with multiple LUN’s.

0 ⇒ Send one command at a time to this target.

1 ⇒ Queue commands to this target; it has multiple LUN’s.

SYN Synchronous Negotiation - Either the initiator or the target may introduce negotiation for synchronous operation. How you set this bit determines whether the RF3880 adapter will attempt to negotiate with the device. Even if you do not set this bit to allow negotiation, if the other device begins negotiation, the adapter will respond.

0 ⇒ Do not initiate negotiation for synchronous data transfer.

1 ⇒ Negotiate for synchronous data transfer.

IAT Inhibit ATN Signal - With this bit you can select whether the adapter will assert the ATN signal during selection of a target. (Some older SCSI devices do not respond to the ATN signal and may stop executing if it is asserted.) Setting this bit will prevent the adapter from negotiating for synchronous transfers, wide transfers, and SCSI-2 and SCSI-3 features. If you enable any of these features with this bit set, you will get errors.

0 ⇒ ATN will be asserted.

1 ⇒ ATN will not be asserted during target selection.

WID Wide Transfers - Either the initiator or the target may introduce negotiation for wide data transfers. How you set this bit determines whether the RF3880 adapter will attempt to negotiate with the device. (Even if you do not set this bit to allow negotiation, if the other device begins negotiation, the adapter will respond.)

0 ⇒ Do not initiate negotiation for wide data transfer 1 ⇒ Negotiate for wide data transfer.

21020285 D User’s Guide