SCSI-1 vs SCSI-2 vs SCSI-3: Difference, Types, Connectors, Features and Working

SCSI-1 vs SCSI-2 vs SCSI-3 is an important computer hardware and computer architecture topic. SCSI stands for Small Computer System Interface and was widely used to connect computers with hard drives, tape drives, scanners, CD-ROM drives and other peripherals. In this guide, we explain what SCSI is, how SCSI works, SCSI-1, SCSI-2, SCSI-3, SCSI connectors, SCSI IDs, termination, transfer rates and the differences between SCSI generations.

If you are preparing for a CSE, BCA, MCA, computer organization or computer hardware examination, this article also provides detailed parameter-based comparison tables, important exam points and frequently asked questions.

Difference between IDE SCSI and SATA interfaces

Characteristics	IDE	SATA	SCSI
Acronym For	(IDE) interface	Serial ATA	Small Computer System Interface
Developed in	1986	2003	developed in 1978 and publicly disclosed in 1981
Pins Used	40 Pins	7 Pins (3 grounds and 4 active data lines in two pairs)	50-pin, 68 pin, and 80-pin
Data Transfer Rate	16 MB/s originally later 33, 66, 100 and 133 MB/s	SATA 1.0–> 150 MB/s, SATA 2.0–>300 MB/s,SATA 3.0 –>600 MB/s	Ultra-640 SCSI: 640 MB/s or 5120 Mbit/s
Supported Devices per Cable	Two	One	Sixteen

SCSI-1,SCSI-2,SCSI-3

SCSI (Pronounced as Skuzzy) is an Acronym for Small Computer System Interface. It is a set of standards for connecting and transferring data between Computer and Peripheral devices. It was developed by Shugart Associates Company in 1981 as a universal and intelligent disk drive interface.

This Interface is generally used for connecting Hard Disk Drives and Tape Drives but can also be used to connect wide range of other devices. This Interface is derived from Shugart Associates System Interface (SASI pronounced as sassy). SASI Controller works as bridge between Disk Drive’s Low level interface and Host Computer. Larry Boucher is considered to be the father of SASI and SCSI. Up to February 1982, ANSI developed this specification as SASI and “Shugart Associates System Interface”. Committee documenting this Standard did not allow it to be named after a company name and after a full day discussion named as SCSI (Small Computer System Interface).