TM 5-6675-318-14
SIMPLIFIED BLOCK DIAGRAM
f. The general theory of operation is provided as an introduction to the plotter
Input to the plotter is from a desktop
system at a simplified block diagram level.
c o m p u t e r t h r o u g h a n H P - I B I n t e r f a c e b u s . T h e ADDRESS switch setting on the inter-
connect PCA determines the bus address that the plotter will respond to. W h e n
addressed to transfer data or status, the HP-IB circuitry sets up the data transfer
and provides the interface between the plotter microprocessor and the controller.
(1) Data transfer is controlled by the processor circuitry which generates
t h e appropriate timing signals to properly sequence the processing of data and
instructions on the plotter bus.
( 2 ) In the memory circuitry, the read only memories (ROMs) store the
i n s t r u c t i o n s a n d d a t a c o n s t a n t s w h i c h t h e p r o c e s s o r a c c e s s e s a n d i n t e r p r e t s . The
r a n d o m access memories (RAMs) are used for temporary storage of microprocessor
calculations and for input/output data.
(3) The internal I/0 circuitry provides an interface between the front panel
PCA circuitry and the plotter bus and also passes velocity information from the
microprocessor to the motor drive circuitry.
(4) The interpolator circuits accept velocity information generated in the
processor and convert this information from digital format to the analog waveforms
required by the motor drivers for the X- and Y-axis motors.
(5) The motor drivers provide both voltage and power amplifications for the
analog signals generated by the interpolator circuits. These signals drive the X-
and Y-axis plotter motors.
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