Tektronix WFM601, Service Manual

Page: 63 / 304

Theory of Operation
3–6
WFM 601 - Service Manual
The Readout State Machine interprets the readout instructions from the
Microprocessor and loads digital data into the DAC. Analog output of the DAC
drives the stroke generators to create the readout segments that are displayed on
the CRT.
This is a serial in/parallel out register for signals that do not need to be synchro-
nized to the video signal.
The Serial Interface is a latch, driven by the Microprocessor, that outputs the
chip select and enables for the serial devices, such as the DACs and the
serial/parallel registers used for the Remote and Front Panel.
There are a number of D-to-A Converters (DACs) used to decode Microproces-
sor instructions and output positioning, gain, and level dc levels to the various
circuits throughout the instrument. The DACs are part of serially loaded and
clocked devices that are commonly referred to as Daculators.
The RS232 input consists of a 9-pin connector and a line driver. It is used to
calibrate the instrument.
The Remote input consists of a 25-pin connector and parallel in/serial out
registers to provide an external interface for remote control of the instrument.
Readout State Machine
Serial Static Outputs
Serial Interface
Digital-to-Analog
Converter
RS232
Remote