Seagate ST157N - General Product Definition; 2.1 SCSI Interface; 2.2 Intelligent Disc Drive Configuration

2 General Product Definition
The ST125N/138N/157N feature an integral SCSI-compatible controller.
This embedded controller performs all of the functions that were pre-
viously implemented
by an add-on controller. And with the controller on-
board, the diagnostic capabilities of the drive are enhanced because the
controller is able to optimize drive performance and error recovery.
2.1 SCSI Interface
The embedded controller supports the SCSI interface as defined in the
ANSI X3T9.2/82-2 document. The interface hardware is capable of trans-
ferring up to 1
.5 megabytes/second using asynchronous data transfer.
Devices
on the SCSI interface are daisy-chained together using a com-
mon cable. Both ends of the cable are terminated. All signals on the in-
terface
are common between all devices.
Refer to the
Seagate SCSI Interface Manual, 36021-001, for a detailed
discussion of the SCSI interface.
2.2 Intelligent Disc Drive Configuration
The ST125N/138N/157N support four commands which determine and
control the drive's operating environment.
Read Capacity:
Inquiry:
Mode Sense:
Mode Select:
Defines the formatted capacity
Defines the drive type and identifies physical
device parameters
Defines
the drive's current operating environ-
n.ent
Provides a method to change
the operating
characteristics of the drive
The host system
can control the following key parameters:
• Total number of blocks available
• Block length
ST125N/138N/157N Product Manual, Rev. C
13