TM 5-6675-323-14
( 2 ) I n t e r p o l a t o r c i r c u i t s . A r e used to take digital data from PCA A3, inte-
grate it, and convert it into analog data which is used to position the plotter pen.
(a) During a 1 msec operating cycle, motor position is advanced the
d e s i r e d a m o u n t f o r t h e 1 m s e c t i m e p e r i o d . T h i s is accomplished by adding one-
eighth of the input velocity vector data word to the position accumulator eight
times.
C o n t r o l signals are developed from the system clock which allows time-
sharing of most of the interpolator circuits.
P C A A3 places six-bit data signals on
IDA bus lines.
B U S and BUS 1 data bits specify the address and the axis part of
the instruction. (See decoder circuits.) Buses 12 thru 15 contain one-half of an
eight-bit X- or Y-axis velocity vector data word.
(b) Three clock periods are used to transfer a complete vector posi-
tion, in one axis, to the analog circuits for pen motor control. During the first
clock period, the least significant bits (LSB's) of the vector are transferred into
t h e i n t e r p o l a t o r . During the second clock period, the most significant bits (MSB's)
are transferred into the interpolator. The third clock period is used for manipula-
t i n g t h e n e w v e c t o r d a t a t o d e t e r m i n e a " d i f f e r e n c e " i n previous pen position and the
n e w p e n p o s i t i o n . T h e difference in value is used to drive the pen to the X- or Y-
position dictated by the original data bytes from the processor.
3-3.2.4 Local Control Circuits.
Are the controls and displays located on two
printed card assemblies:
Front panel PCA A6
Pen stable PCA A7
F r o n t panel PCA card A6.
a.
P r o v i d e s the means of manually entering X- and Y-
axis position data, pen control, and chart hold control to PCA A3. The status of
the various plotter conditions is indicated by the front panel lamps.
(1) Information is manually inputted onto the IDA bus through push-button
switches to display status information and to control the pen. The four indicator
lamps, CHART LOAD, ENTER, ERROR, and OUT OF LIMIT, are driven directly by the front
p a n e l lamp latch located on PCA A5.
( 2 ) With neither PEN UP nor PEN DOWN push-button switch depressed, pen con-
t r o l from PCA A3 is passed through internal I/O flip-flop U7 and through gates U1B
a n d U1A to the pen solenoid.
When either PEN UP or PEN DOWN push-button switches
are depressed, their respective signals override PCA A3.
b . Pen stable PCA card A7.
Provides a status indication of which pens are
present in the stables to the processor.
It houses the four manual pen select
P C A A7 also connects the Y-
switches S1 thru S4 and the five pen stable switches.
initialize switch to PCA A6.
P e n select switches S1 thru S4 provide a manual
means of selecting a desired pen. Depressing one of the push-button pen select
switches causes its appropriate input line to go low.
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