Kenwood TS-440S Serivce Manual page 33

TS-440S
SEMICONDUCTO R
t
PD8251AC (Control unit IC54 )
Data bus
SN7404
5s
5 6
•
D7o.DI4
TXD
Data
bus
buffer
8_ w9
7404 2 .4576MHz
0
ra n
m i
buffer
(P — SI
TX D
RX D
P B7
yl PD7800
E 8
R D
WR
SN74L5138 Ye
L
CTS 5
RTS 6 O 4
041 3
® SN7404
~
• ~
® C/D
~
RD •
•
m
~ :4~•
C S
l0
RESET
• p •
CTS : •
DS R
DTR
MODE M
contro l
R/ R
contro l
I ogic
R X
RD Y
Receiv e
contro I
RX C
SYNDET/BD
Inne r
data bus
Not use
Not use
05 (404010 pin ( Bo rate : 4800 )
5PD7800 INTI 12 pi n
Not us e
tPD8255AC-5 (Control unit IC2, 53)
I/O Port A
I/O Port C
I/O Port B
Group A
Port A
(8 bit )
Group B
Port C
(Lower 4 bit )
R/ W
control
Group B
Port B
(8 bit )
Group A
contro l
Dat a
bu s
buffer
Group B
contro l
74 LS 13 8
i1 At IC2 : Y3
I2
ill At IC53 Y2 I3
Basic functio n
A t A D CS RD WR Functio n
0 0 0 0 1 Data bus °-- Port A
0 1 0 0 1 Data bus Port B
1 0 0 0 1 Data bus Port C
0 0 0
1
0 Port A — Data bu s
0
1
0
1
0 Port B Data bu s
1 0 0
1
0 Port C — Data bu s
1 1 0 1 0
Control register
t—
Data bu s
x x 1 x x
Data bus is in high impedanc e
statu s
1 1 0 0 1
Combination is inhibited
"0" shows low level (L )
"1" shows high level (H)
3 3