Kenwood TS-440S Service Manual page 33

µ,PD8 2 5 1 AC (Control u n it I C 54)
µ PD7800
µ,PD825 5AC-5 (Control u n it I C 2 , 5 3 )
.JJ P D 780 0
16
0
R
1 1
I i i
SEM ICON D UCTOR
Doto bus
8
MODEM
c o n t ro l
t +5VI Vee ��
" '
G N O
)
r
D a t a
b u s
Doto bus
buffer
R e a d i n p u t R O
W r i t e i n p u t W R
Port address
R / W
A l
i n p u t
Port address con t ro l
i n p u t
AO
CS
Reset l n "' u f RESET
Chip select
74LS l38
@
@
A t I C 2 : Y 3
At I C 53 : Y 2
D o t o Tran s ­
T X D
m i t
bus
buffer
b u ffer
I P - S l
T X
R / R
control
l o g i c
R X O
R X
R X C
S Y N OE T/BO
I n ner
doto bus
8
8
Group A
control
8
4
8
8 b i t
I nner
d o t o bus
4
8
G ro u p B
control
Basic function
A , A o R D WR
0 0 0 0 1
0 1 0 0 1
1 0 0 0 1
0 0 0 1 0
0 1 0 1 0
1 0
1 0 0
1 1 0
1 0
x x x x
1
1 1 0 0 1
(L)
"O" shows low l e v e l
" 1 "
shows high l e v e l ( H )
S N 7404 58
T X D
R X D
Not use
C 4 8 0 0 1
N o t use
@
05 (4040> p i n
Bo ro t e :
@
µ P07800 I N T I p i n
N ot use
A
P
l -
7
o
r
1
•
G ro u p A
Por t A
( 8 b i t )
� 1
G rou p A
110
Po r t C
( Uppe r 4 bit)
Port c
G rou p B
- � l - "
Port C
(Lower 4 bit)
PCO
G roup B
Por t B
(8 b i t )
18
PBO
F u n c t i o n
+-
D ata b u s P o rt A
+-
B
D ata b u s P o rt
+-
D ata b u s
P o rt C
+-
P o rt A D ata b u s
B +-
P o rt
D ata b u·s
+-
P o rt C D ata b u s
+-
C o n t r o l r e g i s t e r D ata b u s
D ata b u s is i n h i g h i m p e d a n c e
statu s
C o m b i n at i o n is i n h i bited
TS-440S
"
33