Read/Write Function; Figure 4.6.25 Data Write - Fujitsu M2361A Customer Engineering Manual

4.6.4 Read/Write function
(1) Read/Write basic principles
When the disk is rotating at a nominal 3
t
600 rpm, a read or write may be
performed. The basic principles of the read/write function are as
follows:
a. Data Write
During a write instruction
t
a 0 or
I
is recorded by reversing the
direction of the current flowing in the data head coil. When the
direction of the current flowing in the head coil is reversed, the
magnetic poles of the head are reversed and the direction of magnetic
flux at the gap is revered. The direction of magnetization of the
surface of the disk is then reversed. Each flux reversal means that
a
"1"
or "0" has been recorded on the disk.
Data
Head
- Disk Rotation
Write Current
Write Current
Write Current
_ Disk Rotation
Recorded Bit
Figure 4.6.25 Data Write
h.
Data Read
4 -
88
During a read instruction, the transitions recorded on the surface of
the disk are detected by the head gap. When magnetized in the same
direction continuously, no output is produced. However
t
when a
recorded bit (180-degree flux reversal in the horizontal direction)
passes under the head gap, the mangetic flux flowing in the ring and
coil is reversed and an output pulse is obtained.
B03P-4825-0002A ••• 02