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SCSI Description

3-18 Quantum DLT 8000 Tape System

Reselection Time-Out

Two optional time-out procedures are specified for clearing the SCSI bus if the

initiator waits a minimum of a selection time-out delay and there has been no

BSY signal response from the drive.

1. The initiator asserts the RST signal.

2. The initiator follows these steps:

a) Continues asserting the SEL and ATN signals and releases the DATA BUS.

b) If it has not detected the BSY signal to be true after at least a selection

abort time plus two deskew delays, releases the SEL and ATN signals, allowing

the SCSI bus to go to the BUS FREE phase.

SCSI devices that respond to the RESELECTION phase must ensure that the

reselection is still valid within a selection abort time of asserting the BSY

signal.

3.5.5 Information Transfer Phases

NOTES

1. The tape drive supports wide asynchronous and synchronous data transfers.

2. Both differential and single-ended versions of the tape drive are available.

3. Odd parity is generated during all information transfer phases during which

the device writes data to the SCSI bus, and parity is checked during all

transfer phases in which data is read from the bus by the tape drive. Parity

checking can be disabled (Chapter 2).

4. The ANSI SCSI specification refers to mini-libraries as “medium changers.” In

this chapter the term “mini-libraries” is used to describe these devices.

5. The DLT 8000 supports block size of 1 byte to 16 Mbytes.

6. Disconnects from the SCSI bus are done at regular intervals during

information transfer phases to allow other devices to access the bus. These

disconnects are user-configurable via the Disconnect-Reconnect Page of the

SCSI MODE SELECT command.

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Quantum DLT 8000 Manual Página 120