Chapter 1 Scsi Bus; System Configuration - Fujitsu MAN3184 SERIES Specifications

CHAPTER 1
This chapter describes the configuration, physical and electrical characteristics, interface protocol, and
operations of SCSI buses.
Note:
The IDD operates as a target (TARG) on the SCSI bus. The IDD is called "TARG" in this
chapter except when clear identification is required.
1.1

System Configuration

Up to 16-bit SCSI series models can be connected to the system via the SCSI bus. Figure 1.1 gives
an example of multi-host system configuration.
Each SCSI device operates as an initiator (INIT) or a target (TARG). Only a single INIT and a
single TARG selected by this INIT can operate simultaneously on the SCSI bus.
The system configuration allows any combination of a SCSI device to operate as the INIT and a
SCSI device to operate as the TARG. Also, any device having both the INIT and TARG functions
can be used on the SCSI bus.
Each SCSI device is assigned a unique address (or SCSI ID). The SCSI ID corresponds to a bit
number of the SCSI data bus. While the INIT uses a logical unit number (LUN) to select an I/O
unit to be connected under TARG control.
SCSI BUS
1.1 System Configuration
1.2 Interface Signal Definition
1.3 Physical Requirements
1.4 Electrical Requirements
1.5 Timing Rule
1.6 Bus Phases
1.7 Bus Conditions
1.8 Bus Phase Sequence
1.9 SCAM
1.10 Ultra SCSI
1.11 Low-Voltage Differential
1.12 SCSI Bus Fairness
C141-E123-01EN 1 - 1