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MACHINE DESCRIPTION
• The IBM 5444 Disk Storage Drive is a direct-access
storage unit providing up to 40 million bits of data
storage.
• Three models are available.
• Data
is stored on both sides of magnetic recording
disks.
• A removable upper disk forms part of the IBM 5440
Disk Cartridge.
• Machine operations of accessing, reading, and writing
are controlled from the
using
system.
• Read and write operations are accomplished using
read/write (R/W) heads.
• An actuator carries the read/write heads over the disk
surfaces.
The 5444 Disk Storage Drive (Figure 1-1) is a
direct-access disk file that provides auxiliary storage for
small computer systems. The unit is designed to be
mounted within the frame of the using system.
The storage medium is a 14 in. (356 mm) diameter
disk, coated on both sides with magnetic iron oxide. The
5444 can accommodate two such disks mounted on a
common drive spindle. The lower disk is permanently
mounted in an enclosure at the base of the drive spindle.
The top disk forms part of the 5440 Disk Cartridge and
is removable.
Data is stored in concentric tracks on the recording
surfaces. To replace any defective tracks, three extra
tracks on each surface can be used. One further extra
track per surface is available for use only by the
customer engineer (CE).
Three models of the 5444 are available, the main
differences being the storage capacity and number of
disks used.
Differences between Models
Model 2 is described in this manual; any differences
between models are dealt with where appropriate.
5444 (<30100) FETMM
(5/70)
1-1
Cartridge Bottom Cover
(Inverted)
Cartridge
Clamp Arms
IBM 5440 Disk Cartridge
Top Cover
Figure 1-1. IBM 5444 Disk Storage Drive
[07461]
Model 1: Two disks. Data is stored on both disks, on 100
tracks of each of the four recording surfaces. The total
storage capacity is 20 million bits.
Model
2: Two disks. Data is stored on both disks, on
200 tracks of each of the four recording surfaces. The
total storage capacity is 40 million bits.
Model 3: One disk (removable) only. Data is stored on
200 tracks on each recording surface of this disk. The
total storage capacity is 20 million bits.
Access Assembly
Drive Motor
Major Units
• The major units are described in detail in Chapter 2.
The 5444 contains two 14 in. (356 mm) magnetic
recording disks on a common drive spindle. The lower
disk is fixed and the upper disk removable forming part
of the IBM 5440 Disk Cartridge. Writing and reading
uses four read/write heads: one for each recording
surface. The four heads are supported in a carriage that
Chapter 1. Introduction
moves on linear ball slides within the actuator frame.
Movement of the carriage is from a leadscrew driven
via a flexible drive disk which, in turn, obtains its
motion from a constantly-turning layshaft. Forward or
reverse motion of the carriage is given by clutches acting
on the flexible drive disk. The heads are stopped at the
correct track by a detent on the leadscrew.
A
drive
motor rotates the disks and the layshaft.
The upper removable disk (the only disk on Model 3)
is
permanently enclosed in the 5440 Disk Cartridge. The
cartridge may be easily removed from the 5444 and can
be fitted to other cartridges and 5444's. Cartridge
interchangeability depends on model. Model 1 reads
only the first 100 tracks of a disk and so reads only
part
of a disk written on a Model 2 or 3.
MACHINE SAFETY AND DATA PROTECTION
Safety devices on the 5444 control start/ stop sequencing
and actuator operations and protect recorded data. The
safety devices include drawer and cartridge interlocks to
prevent access during operation, and interlocks to
prevent the 5444 starting when the 5444 is open. The
CE can override the interlocks during maintenance.
The 5444 includes sensors to monitor the write
circuits during read/write operations. If an unsafe
condition occurs, a 'data unsafe' signal is sent to the
using system to inhibit all further read/write operations
until the cause of the unsafe condition is removed.
MACHINE OPERATIONS
• All machine operations are controlled by signals from
the using
sys~em.
Start/Stop Sequence
• Start and stop sequences are controlled by a '+24V
file start' line from the using system.
Before the start-up sequence commences, the using
system power supplies must be switched on, and the
drawer and cartridge interlocks made. Start-up sequence
commences with line '+24V file start' activated, and
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