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When
there
is
a pre-erase delay 390-microsecond time out, the erase
current source is turned on.
The clocking of the waveform generator during write operation provides
a
trigger to
the post-erase delay one shot, and does not allow it to
time out until all data is written.
N Internal Write
and
keeps
+12
erase time.
Busy is active until the end of the post-erase delay,
volts D. C. on the read/write diode matrix during the
The duration of a write operation is from the true going edge of write
Enable
to
the
false going edge of Trim Erase.
This is indicated by
the Internal Write Busy waveform (figure 4-8).
Read Data circuits
The read electronics consist of:
1.
Read Only and Side Select circuits
2.
Read Amplifier and Linear Phase Filter
3.
Differentiator
4.
Comparator, Time Domain Filter, and Digitizer
The Read Only circuits are used to isolate the read amplifier from the
voltage
excursion
across
the
head during a write operation.
The
side select is used to enable one of the read/write head(s).
The
drive
must
be
selected by the user's system before reading can
begin.
In addition to the requirements established in this section, a
100
microsecond
delay
must exist from the trailing edge of the Trim
Erase
signal
to
allow
the
read
amplifier
to
settle
after the
transient
caused
by
the
Read
Only
circuit returning
to the Read
mode.
The
output
signal
from
the
read/write head is amplified by a read
amplifier, and
filtered
by
a
linear
phase filter to remove noise.
The
linear
output
from
the filter is passed to the differentiator,
which
generates
a
waveform
whose
zero crossovers correspond
to
the
peaks
of
the
Read
signal.
Then,
this
signal is fed to the
comparator, time domain filter, and digitizer circuitry (Figure 4-9).
4.6
SPINDLE CUNTROL
The components of the drive required to control the spindle are:
1.
Spindle Motor and Spindle Assembly
2.
Spindle Motor Enable circuit
3.
Spindle Motor Control circuit
4.
Diskette Enable Switch
4-12
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