TM 5-1260-206-34
Circuitry to Determine the X or Y Position of the Photo-Carriage
(Cursor Coil) - The position (X or Y) detector determines the incremental
c h a n g e in the position of the cursor coil. The digital signals (X GRID
or Y GRID) from the analog (A) board are compared to a 3-kHz reference
s i g n a l generated in the error detector circuit. A difference in phases
caused by movement of the cursor coil relative to the data grid produces
pulses; each one corresponding to 0.001 inch. These pulses are applied
to the up/down count and sign detector circuits. The zero reference point
can be set for any position of the cursor coil by pressing
sign detector logic senses this movable origin and generates a SIGN X o r
SIGN Y signal.
( 5 ) Multiplexer Storage (F) Card - T h e multiplexer storage card
p r o v i d e s the following functions:
X-axis encoder (AX) counter a n d storage register
Multiplexer logic
BCD to ASCII code converter
Control logic
The circled numbers are keyed to F0-5.
X-Axis Encoder (AX) Counter and Storage Register Circuitry - The 500
p u l s e / r e v o l u t i o n shaft angle encoder output is applied to the 4-bit up/
down counters. T h e s e counters feed in parallel to the storage register.
X and Y Coordinates Storage Register Circuitr y - These 4-bit parallel
s h i f t registers accept the X-coordinate output from the axis (B) card and
the Y-coordinate output from the axis (C) card.
M u l t i p l e x e r L o g i c C i r c u i t r y - The X, Y, and AX data from the storage
r e g i s t e r s is applied to the two-stage multiplexer. T h e multiplexer
shifts this data out to the BCD to ASCII converter one BCD digit at a
t i m e . Selection control is provided by the BCD 1-8 inputs from the con-
t r o l (G) card.
BCD to ASCII Code Converter Circuitry - The code converter iS a 32-word
by eight-bit PROM. The converter is addressed by the BCD data and the
A S C I I outputs are applied to the Calculator. The XFR COMPLETE signal is
f e d to the control logic.
C o n t r o l Logic Circuitry - This counter circuit controls each BCD character
stepped through the multiplexer and code converter. I t is driven by the
C a l c u l a t o r I/0 signals applied through the control (G) card.
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