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Video Process C
The V board is the second board (of four) in the video processing chain.
Its purpose is to take the main component video and either reduce the
number of scanning lines for a Twin View picture or double the number of
lines for a picture that will simulate that of an HDTV picture. The signal
path is dependent upon whether a single or twin picture is called for.
Single Picture
The single picture main signal path is through the Digital Reality Creation
circuitry. The output is component video that is selected by switch IC528
to feed the Video Processor IC on the next (B) board.
S in g le P ic t u r e M a in S ig n a l P a t h
C o m p o n e n t
I n p u t
D R C
M a in c o m p o n e n t
P r o c e s s in g
v id e o in p u t
C N 5 0 3 / p in s 7 , 9 ,
1 1 .
S w it c h I C 5 2 8
T w in p ic t u r e
S in g le ( m a in )
p ic t u r e
B u f f e r s Q 5 6 4 –
C o m p o n e n t v id e o
Q 5 6 6
Twin View Picture
When Twin View is selected, the main picture path is through the MID IC.
This IC uses two external memories (IC501 and IC502) to hold the infor-
mation from each picture. When the information is needed, this can be
selected at the right time to produce two pictures on the screen simulta-
neously. The second picture comes from the sub picture information in-
put at IC506/pins 11-23.
O u t p u t
P u r p o s e
S in g le
lin e s d o u b le d
( m a in )
4 8 0 i
t o
9 6 0 i
p ic t u r e
lin e s
C o m p o n e n t
S e le c t s s in g le
v id e o
o r d o u b le ( t w in )
p ic t u r e
C o m p o n e n t
C u r r e n t
v id e o
a m p lif ie r s
43
T w in V i e w P i c t u r e M a in S i g n a l P a t h
C o m p o n e n t
I n p u t
B u f f e r s
M a i n
t r a n s i s t o r s
c o m p o n e n t
Q 5 7 2 - Q 5 7 4
v i d e o i n p u t
C N 5 0 3 / p in s 7 ,
9 , 1 1 .
M u l t i I m a g e
C o m p o n e n t
D r i v e r
v i d e o f r o m :
I C 5 0 6
♦
M a i n p a t h -
B u f f e r
t r a n s i s t o r s .
♦
S u b P a t h –
I C 6 0 7
F il t e r s
T w in V i e w
F L 6 0 4 -
C o m p o n e n t
F L 6 0 6
v i d e o
F il t e r s
T w in V i e w
F L 6 0 8 &
C o m p o n e n t
F L 6 0 7
c o l o r ( C r , C b )
S w i t c h
T w in V i e w
I C 5 1 9
C o m p o n e n t
v i d e o p i n s 1 , 5 ,
1 3 .
C o m p o n e n t
c o l o r p in s 2 ,
1 2 .
S w i t c h
T w in p ic t u r e
I C 5 2 8
S in g l e ( m a i n )
p i c t u r e
O u t p u t
P u r p o s e
I C 5 0 9 / p in s :
S u p p li e s s u f f ic i e n t
c u r r e n t t o d r i v e t h e
7 7 ( Y ) = 2 . 3 V p - p
n e x t i n p u t s t a g e .
7 6 ( C b ) = 1 V p - p
7 1 ( C r ) =
1 V p - p
C o m b i n e d m a in
R e d u c e s m a in &
a n d s u b p i c t u r e
s u b p ic t u r e s iz e .
i n o n e
S t o r e s r e m a i n in g
c o m p o n e n t
i n f o in e x t e r n a l
v i d e o o u t p u t –
m e m o r i e s .
p i n s 7 1 , 7 6 , 7 7 .
C o m b i n e s b o t h
p i c t u r e s i n t o o n e
o u t p u t ( T w i n V i e w )
p i c t u r e .
T w in V i e w
R e d u c e s
C o m p o n e n t
r e m a in i n g d ig i t a l
v i d e o
n o i s e .
T w in V i e w
N o t u s e d i n U S A
C o m p o n e n t
m o d e l .
c o l o r ( C r , C b )
T w in V i e w
S w i t c h r e m a i n s i n
C o m p o n e n t
t h e f i x e d p o s it io n
v i d e o
s h o w n ( U S A
m o d e l ) .
C o m p o n e n t
S e le c t s :
v i d e o .
s i n g le o r d o u b le
Y = . 8 V p - p ,
( t w in ) p i c t u r e
C r / C b = . 5 V p - p
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