Mass Storage Device Interfaces; Historical Background - Red Hat ENTERPRISE LINUX 4 - INTRODUCTION TO SYSTEM ADMINISTRATION Administration Manual

Chapter 5. Managing Storage
to the mass storage device, which then internally performs the conversion to the geometry-based
address required by the device's control circuitry.
Because the conversion to a geometry-based address is always done by the device itself, it is always
consistent, eliminating the problem inherent with giving the device geometry-based addressing.

5.3. Mass Storage Device Interfaces

Every device used in a computer system must have some means of attaching to that computer system.
This attachment point is known as an interface. Mass storage devices are no different — they have
interfaces too. It is important to know about interfaces for two main reasons:
There are many different (mostly incompatible) interfaces
•
Different interfaces have different performance and price characteristics
•
Unfortunately, there is no single universal device interface and not even a single mass storage device
interface. Therefore, system administrators must be aware of the interface(s) supported by their orga-
nization's systems. Otherwise, there is a real risk of purchasing the wrong hardware when a system
upgrade is planned.
Different interfaces have different performance capabilities, making some interfaces more suitable for
certain environments than others. For example, interfaces capable of supporting high-speed devices
are more suitable for server environments, while slower interfaces would be sufficient for light desktop
usage. Such differences in performance also lead to differences in price, meaning that — as always
— you get what you pay for. High-performance computing does not come cheaply.

5.3.1. Historical Background

Over the years there have been many different interfaces created for mass storage devices. Some have
fallen by the wayside, and some are still in use today. However, the following list is provided to give
an idea of the scope of interface development over the past thirty years and to provide perspective on
the interfaces in use today.
FD-400
An interface originally designed for the original 8-inch floppy disk drives in the mid-70s. Used a
44-conductor cable with an circuit board edge connector that supplied both power and data.
SA-400
Another floppy disk drive interface (this time originally developed in the late-70s for the then-
new 5.25 inch floppy drive). Used a 34-conductor cable with a standard socket connector. A
slightly modified version of this interface is still used today for 5.25 inch floppy and 3.5 inch
diskette drives.
IPI
Standing for Intelligent Peripheral Interface, this interface was used on the 8 and 14-inch disk
drives deployed on minicomputers of the 1970s.
SMD
A successor to IPI, SMD (stands for Storage Module Device) was used on 8 and 14-inch mini-
computer hard drives in the 70s and 80s.
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