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TECHNICAL DESCRIPTION
main module.
contained on a separate I/O module, (7006) into which the 631 module
plugs in. The relevant schematic drawings are shown in brackets for each
section of the circuit.
6.7.1. Microcontroller (6120-32)
At the heart of the 631 character generator module is an 8032
microcontroller, (MCU) U14. Its three 8 bit bi-directional ports and 8 bit bus
provide peripheral interfacing to the rest of the circuits. Program memory is
contained on EPROM U17.
internally by the MCU.
remote control connector, serial I/O for the external RS-232/RS-422 port,
and other control pins for various circuit elements.
An onboard oscillator, also part of the MCU, is crystal controlled.
11.50849 MHz frequency is internally divided by 12, resulting in a
processor operating frequency of approximately 960 KHz.
6.7.2. Sync Separator (6120-33)
Composite video, buffered on the separate I/O module, and on the main
PCB by Q3 and Q2, is AC coupled into U5b. Immediately following each
horizontal sync pulse, a sample pulse is generated at U5c which allows
U5a to compare the actual DC level of the video to ground potential. If they
are not equal, U5a generates an error signal which adjusts the bias point of
Q3 thus ensuring proper operation of the video keyer and sync separator
with varying video and sync levels. Comparator U3 switches when the
negative sync tip goes below its half amplitude point, producing composite
SYNC.
Composite SYNC is integrated by U2c to derive vertical sync
(VSYNC) which sets flip flop U13a, enabling sync pulse counters U11 and
U12. The next sync pulse, (the first vertical serration) generates an output
on U11 pin 7 which, when ORed with 3/4 H from U7b and SYNC clocks on
U9a, generating a frame pulse interrupt (FP INT) to the MCU.
6.7.3. Character Generator Interface
The character inserter logic and keyer are contained on a separate circuit
sub-module (6231) which connects to the main circuit card via header J4 &
J5. Video in and out, and the MCU address and data bus are fed up the
header from the main board. Jumper J3 on the 6120 board should be
installed in the rear position.
The submodule used for the 631 Character generator is identical to the VITC
generator submodule. Jumper JP3 at the front of the sub-module selects
the VITC mode when it is in the HI position and the Character mode when it
is in the LO position.
applies to both the VITC and Character generator uses of this board.
Model 4025 Film Footage Encoder Manual
Video input buffers and all input/output connectors are
Scratch pad and data RAM are provided
MUART U21 provides parallel inputs from the
See section 6.7 for the circuit description which
Its'
Page 6-22
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