Shugart SA455 - 1.2.4 Reliability Specifications; 1.3 FUNCTIONAL CHARACTERISTICS; 1.3.1 Read;Write and Control Electronics; 1.3.2 Drive Mechanism

1.2.4 Reliability Specifieatianli
MTBF: 10,000 POH under typical usage.
PM: Not required.
MTTR:
:30 minutes.
Error Rates:
Soft
Head Errors: 1 per 10" bits Hmd.
I--Iard Head Errors: 1 per 10
1
:.1 bits read.
Seel~ Errors: 1 per 10
6
seeks.
Media Lif('.:
Passes per Trac!(: 3.0 x 10('
Insertions: 30,000 +
j\.3 FUNCTIONAL CHARACTERiSTICS
The SA455/465 consists of read/write and control electronics. drive mechanism, read/write head, and precision
track positioning mechanism. These components perform the following functions:
a. Interpret and generate control signals.
b. Move read/write heads to the desired track.
c. Read and write data.
The interface signals and their relationship to the internal functions are shown
In figure 1-2.
1.3.1 Read/Write and Control EIE~ctronics
The electronics package contains:
a, Index detector circuits
b. I-lead position actuator driver
c, Read/write amplifier and liransition detector
d. Writ
e protect detector
e. Drive select circuit
f. Drive motor control
1.3.2 Drive Mechanism
The dc drive motor under servo . spE~ed control (using an integral tachometer) rotates the spindle at 300 rpm
through a direct drive system.
An expandable collet/spindllB assembly provides precision media positioning to en-
sure data interchange.
1.3.3 Positioning Mechanics
The read/write head assembly is accul'atelypositioned through the use of a band positioner which is attached to the
head carriage assembly. Precise track location is accomplished as this positioner is rotated in discrete increments by
a stepping motor.
1.3.4 Read/Write Heads
The proprietary heads are a single elementceramic read/write head with tunnel erase elements to provide erased
areas between data tracks. Thus normal interchange tolerances between media and drives will
not degrade the
signal·to-noise ratio and diskette interchangeability
is ensur,ed.
The
read/ write heads are mounted on a carriage which is located on precision carriage ways. The diskette is held
in a plane perpendicular to the
read/write heads by a platen located on the base casting. This precise registration
assures perfect compliance with the re,ad/write heads. The
read/write heads are in direct contact with the diskette.
The
h(~ad surface has been designed to obtain maximum signal transfer to and from the magnetic surface of the
diskette with minimum head/diskette wear.
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