Posted
: 10/3/99
Written by:
Heat
Introduction
This article assumes you already know how to build an IDE based system.
SCSI stands for Small Computer Systems Interface. It was first started in 1979.
Today, the SCSI standard can be divided into SCSI-1 and SCSI-2 (SCSI wide and
SCSI wide and fast) and recently SCSI-3. SCSI-2 is the most popular version of
SCSI and is found in scanners, hard disk drives (older), CD-ROM
players/recorders, and tape backup drives. SCSI-3 adds new functionality and
performance improvements. SCSI-3 is mostly used for hard drives as of now.
Why should I go all SCSI?
Before you go all SCSI, be sure you have money, SCSI is down right expensive! :)
Here are some benefits of going all
SCSI.
Flexibility
With IDE, your limited to IRQ's and number of IDE channels. Each IDE channel
uses 1 IRQ, so on a standard motherboard will you use 2 IRQ's and can only have
2 devices per channel. 4 maximum, this is by default. Sure you can add another
IDE controller, but you still cannot get up to 15 devices and still use 1 PCI
slot! With SCSI, you can have up to 15 devices, all using just 1 IRQ! SCSI is
supported by a very wide range of devices, here are just a few: CDROMs, DVDs,
CDRs, CDRWs, Hard Drives, Tape Drives, and Scanners.
Multitasking
Unlike IDE, SCSI devices allow one device to transfer data while another is
seeking. This helps gain performance in a multitasking operating systems such as
Windows NT or Linux.
Wider Bus
Theoretically speaking, the fastest SCSI bus has a bandwidth of 160MB/s, but
this requires a 64 bit 66 Mhz PCI slot (not found in common systems, mostly
servers). So with your average PC, the max is 80MB/s. This means your hard
drives can transfer up to 80MB/s (theoretically, actual transfer rates are much
lower) IDE just recently started using 66MB/s (ATA-66), but most people who
haven't built a new system or upgraded still have ATA-33 (33MB/s) at this time.
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