Repair manual

2-16
THEORY OF OPERATION
D. Logic Controller P.C. Board
The Logic Controller P.C. Board contains all the necessary electronic circuitry to con
trol the Digital Palette operations specified by the computer software and to communi
cate with the host computer.
The electronic circuits that make-up the Logic Controller P.C. Board are:
o Microprocessor Control Network
o Erasable Programmable Memory (EPROM)
o Random Access Memory (RAM)
o Video Signal Generation
o Vertical Deflection
o Horizontal Sync Signal Generation
o Auto Luminance (Brightness)
o Digital Palette Operations (Camera Back, Filter Wheel Motor, and Position)
Figure 2-3 shows a simplified block diagram of the Logic Controller P.C. Board. Refer
to the Logic Controller P.C Board logic schematics (Figure 2-9, sheets 1 - 7) in Section
G of this Service Manual for detailed information pertaining to the logic circuits on the
Logic Controller P.C. Board. Both the simplified block diagram and the detailed logic
schematics should be referenced while reading the following functional descriptions of
the circuits that make-up the Logic Controller P.C. Board
1. Microprocessor Control Network
The Microprocessor Control Network (Figure 2-9, sheet 1) consists of:
a. Microprocessor (CPU)
b. 40 MHz Clock
c. Reset Control
d. Address Latches
e. Microprocessor Control PAL
f. Communications Bus
a. Microprocessor (CPU)
The CPU (Figure 2-9, sheet 1) used in the Digital Palette to control the
sequential exposure of a computer-generated image is an enhanced
80186, 16-Bit microprocessor. Its purpose is to process the instructions
supplied to it by the host computer software. In a sense, this
microprocessor is the Digital Palette's brain: it controls the Digital Palette
by directing the necessary hardware functions that controls the sequential
exposure.
When the microprocessor receives instructions via the applicable parallel