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3.2
ELECTRICAL INTERFACE
This section gives a description of the signal levels, the
driver/receiver
FD1165.
3.2.1
Signal Levels
The input and output signals are at TTL levels and have the
following electrical specifications.
True = Logic 0 (low level), 0 to +0.4 Vdc
False = Logic 1 (high level), +2.5 to +5.25 Vdc
3.2.2
Driver/Receiver Circuits
Each driver circuit delivers a signal, on an interface line,
to the controller from the disk drive.
are the open-collector
(IC).
The SN7438 driver circuits sink a maximum current of
40 mA at the low level.
Each receiver circuit receives a drive signal from the con
troller.
The receiver circuits are Large Scale Integration
(LSI) gate circuits that terminate with 150-ohm resistors.
Lines receiving at high speeds use a Schmitt trigger gate.
Figure 3-1 shows the recommended driver/ receiver circuits.
Figure 3-1
circuits,
and
type of SN7438
Driver/Receiver Circuits
3-2
the interface
All driver circuits
Integrated Circuit
lines of
the
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