PC Hardware

Memory Management

SCSI host adapters typically have their own ROM chips. For MS-DOS systems, put the appropriate "X=" statements in the EMM386.EXE line of the CONFIG.SYS and the appropriate EMMEXCLUDE= statement in the SYSTEM.INI file. (For more details about configuring these files, see Tutorial 15, "Software: MS-DOS and Windows 3.x.") A missing or erroneous "exclude" statement can cause intermittent lock-up problems.

Costs and Benefits of SCSI

Initially, the cost of a SCSI system and SCSI devices is greater than IDE. However, there are several environments in which a SCSI system might justify the increased cost. Some ideal uses for SCSI include:

  • File servers.

  • Workstations (both graphical and audio).

  • Multitasking systems.

  • Systems moving large amounts of data between peripheral devices.

  • Systems with a large number of peripheral devices.

  • Systems requiring fault tolerance (mostly file servers).

The Future of SCSI

SCSI continues as the device of choice for systems in which speed and compatibility are important. The ability of the SCSI format to provide fast and efficient fault tolerance for network systems through the use of RAID (redundant array of independent disks) will keep it as the drive of choice for networks.

Although it is not required, the SCSI drive is generally preferred over IDE by Windows NT system designers for its performance and flexibility. SCSI continues to be more expensive than IDE, but SCSI's ability for RAID, hot plugging (changing drives without shutting down a system), and machine independence will keep it popular for workstations and servers.