Chapter 7 Scsi Bus; System Configuration - Fujitsu MCM3064SS Product Manual

CHAPTER 7 SCSI BUS

7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
This chapter describes the structure of the SCSI bus, electrical conditions,
interface protocol and their operations.

7.1 System Configuration

Up to eight SCSI devices can be connected to the SCSI bus. Figure 7.1 shows a
sample system configurations of a multi-host system. Number of devices to be
connected is restricted according to the synchronized transfer speed. Refer to the
related specifications for detail. Communication on the SCSI bus is allowed
between only two SCSI devices, an initiator (INIT) and a target (TARG), at any
given time.
In the configured system, any combination is allowed for an SCSI device to work
as an INIT and as a TARG. Also, there may be an SCSI device that works as both
an INIT and a TARG.
A unique address (SCSI ID) is assigned to each SCSI device. The SCSI ID
corresponds to one bit of the SCSI data bus. The INIT designates an I/O device
connected to the TARG by its logical unit number (LUN).
The SCSI ID of the ODD can be selectable among #0 to #7, but the LUN is fixed
to #0.
C156-E228-02EN
System Configuration
Interface Signal Definition
Physical Requirements
Electrical Requirements
Timing Rule
Bus Phases
Bus Conditions
Bus Sequence
The ODD operates on the SCSI bus as a TARG. In this chapter, the
ODD is represented as "TARG" except where some special
distinction must be made.
7-1