General Description; Introduction; Cartridge Disk System Configuration - Xerox 7250 Reference Manual

1. GENERAL DESCRIPTION
INTRODUCTION
The Xerox Model 7250;7251/7252 Cartridge Disk System
provides fast, auxiliary, random-access memory for Xerox
computers. It is a moving-head, rotating disk system for
use as secondary storage with Xerox 530 and Sigma 3 com-
puters (16-bit words), as well as with Sigma 5/6;7/8
computers (32-bit words). Cartridge disks may be uti-
1ized for system, processor, and public library residence,
for on-line permanent fi Ie storage, and for temporary
file storage. By combining high performance with low
cost, the Cartridge Disk System offers a flexible solu-
tion to the data handling problems encountered by sys-
tem designers.
A Cartridge Disk System incfudes a Model 7250 Controller,
which accommodates as many as four disk drives (see Fig-
ure 1). The drives, which may be any desired combination
of Model 7251/7252 Disk Drives, employ the Model 7254
Disk Cartridge as a storage medium. Each controller ac-
commodates a storage capad ty of up to 18.4 mi II i on bytes.
Each drive has a capacity of either 2.3 mi Ilion bytes (7251
drive with one disk cartridge) or 4.6 million bytes (7252
drive with one disk cartridge and one fixed disk). The term
disk as used in this manual implies a single circular plate
with two recording surfaces.
In order to use this manUQI effectively, the reader must be
familiar with the applicable Xerox computer reference
lOP Channel
7251/7252
Disk Drive
f-- - - - -
7254 Disk
Cartridge
7250
Controller
1 - - - - - -
Ma i n tenance
7251/7252
Disk Drive
Panel
Multiple
Drive
Selection
Unit
7251/7252
Disk Drive
1------
~----
7254 Disk
7254 Disk
Cartridge
Cartridge
Maximum of 4 disk drives
Maximum of 8 disks
Each disk has a unique device address
Figure 1. Cartridge Disk System Configuration
7251;7252
Disk Drive
-----
7254 Disk
Cartridge
General Description