Hp C737990900 User Manual download pdf (Page 23)

Interface Implementation 23

Interface Implementation

still tied low, so in this case it will use the soft name last downloaded. This

will allow drive access without confusing the host.

Field Replaceable Units

An FRU code identifies which part of the hardware is considered to have

failed. These codes turn up in sense data byte 14 and as the sense code

qualifier for sense codes 4400h (internal target failure) and 40XX (diagnostic

failure).

Although there are no actual Field Replaceable Units on HP Ultrium drives, the

following sub-assemblies can be replaced at Repair Centres:

Descriptions of Signals (Parallel SCSI only)

The SCSI interface consists of 27 signals—9 control lines, 16 data lines and 2

parity lines. A description of these signals is given in the following table.

■ Drive PCA ■ Head Assembly

■ Mechanism ■ Front Panel

Signal Name Driven by Description

-BSY

Busy — OR-tied signal used to indicate that the SCSI bus is in use.

-SEL

Select Initiator

Target

Used to select a target during the Selection phase.

Used to select an initiator during the Reselection phase.

-C/D

Control/Data Target Indicates whether control or data information is on the data

bus.

True (low) Control information

False (high) Data information

-I/O

Input/Output Target Controls the direction of data movement on the bus with

respect to the Initiator. This signal is also used to distinguish

between Selection and Reselection phases.

1 ... 22 23 24 ... 174

No comments

Hp C737990900 User Manual Page 23