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WAITE ENABLE
TRIM ERASE
INTERNAL
WAITE BUSY
NWAITEDATA
WAITE
WAVEFORM
GENERATOR
NOTE1
r
I
I
390
~
secs-
L+--
800
~
I
I
W
I
usecs
I
I
~
I
"
r
_____ 1 _ _ .., _ _ _ _ _ _ _ _ _ _ _ _ _
i_ ...
~
S
!
NOTE 2
I
I
I
I
WRITE CURRENT~k----N,
I
I
I
- - - - I - - - - ·-
7~--.... -
NOTE~
NOTES,
1.
t
•
0
•
250 MILLISECONDS AFTER DRIVE MOTOR
STARTS OR 20 MILLISECONDS AFTER LAST STEP
PULSE,
'WHICHEVER IS THE LATEST TIME
Figure 1-4
1
_---r
I
I
I
I
I
I
I
2.
UNSYNCHRONIZED
3.
8.5 MA PEAK TO PEAK
4
.
4
u
SECONDS
MINIMUM,
8
u
SECONDS
MAX
IMUM
Write Operation Timing Diagram
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 shown (see Figure
1-4).
The Read electronics consist
of:
1
.
Read Switch/Side Select
2.
Read Amplifier
3.
Filter
4.
Differentiator
5.
Comparator and Digitizer
The Read switch is used to isolate the Read Amplifier from the voltage excursion across the magnetic head dur-
ing a Write operation. The side select is used to enable one of the Read/Write/Erase heads.
The disk drive must be in a ready condition before reading can begin
.
As with the data recording operation, this
ready condition must be established by the user system
.
In addition to the requirements established in this sec-
tion, a 100 usec delay must exist from the trailing edge of the Trim Erase signal to allow the Read Amplifier to set-
tle after the transient caused by the Read switch 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 (see Figure
1-5).
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 Com-
parator and the Digitizer circuitry.
1-10
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