TM 5-1260-206-34
The circled numbers are keyed to F0-3.
C l o c k Pulse Circuitry - The input 6-MHz oscillator signal is divided-by-
two to give an output of 3-MHz. Two 3-MHz outputs are provided, CP1 and
CP1 . CP1, the main system clock pulse, has a pulse width of approximately
80 nanoseconds. Signal CP1 is used to generate a 3-kHz reference square
wave (REF), and a 30-Hz clock with a pulse width of 80 nanoseconds (CP4).
CP4 acts as a switch sampling pulse to logically debounce switch contacts
f o r use in the logic.
o n initial power-up when
is pressed. T h e inputs to the clear logic
circuitry are ZERO and AUTO CLEAR. A clear condition occurs when a high
is applied to ZERO input or a low to AUTO CLEAR. A low is automatically
applied to AUTO CLEAR for a brief time when system power is turned on.
Either signal outputs a low system reset pulse (CAL) and drives CLEAR
LOCKOUT low.
H o l d Logic Circuitry - T h e input to the hold logic circuitry is grounded
keeping HOLD IND at a logic low.
(3) Analog (A) Card - The analog (A) card provides the following:
System 6 M H Z c l o c k
AUTO CLEAR logic
Driving signal for the cursor coil
Lockout detection
The circled numbers are keyed to F0-3.
System 6 MHz Clock Circuitry - The clock is composed of a 6-MHz crystal-
c o n t r o l l e d o s c i l l a t o r . It provides the time base (CP1 and CP4) for the
D A C circuits.
AUTO CLEAR Logic Circuitry - When power is applied, this circuit generates
a low AUTO CLEAR pulse. This momentary low resets the counter circuits
a n d initializes the system.
C u r s o r Coil Excitation Generator - The cursor coil excitation generator
p r o v i d e s the 3-kHz excitation current required by the cursor coil. This
current generates a magnetic field which-is detected by the OMS data grid
a s the cursor coil/photo-carriage is moved.
L o c k o u t Detection Circuitry - The cursor coil lockout detector activates
the sonalert and generates a SYNC inhibit signal when data grid signals
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