Intel MCS48 User Manual page 129

APPLICATION
EXAMPLES
.40
,26
,,20
INPUTS
V(X
V DD
Vss
XTAL
1
8049
8048
8748
8035
*
8039*
TO
T1
INT
ALEPSEN
PROG WR RD
P10
P11
P12
P13
P14
P15
P16
P17
P20
P21
P22
P23
P24
P25
P26
P27
DBO
DB1
DB2
DB3
DB4
DBS
DB6
DB7
I/O
»EA =
5V FOR
8035/8039
+5V
40
10
CAN
BE SUPPLIED BY SYSTEM
~
*
RESET OR PORT
LINE
OF
8048
GND
20
v
C c
Vss
ADO
AD1
AD2
AD3
AD4
AD5
AD6
AD7
IO/M
RD
WR
8155
256
x 8
RAM
RESET TIMER
OUT
TIMER
IN
TIMER
PAO
PA1
PA2
PA3
PA4
PA5
PA6
PA7
PCO
PC1
PC2
PC3
PC4
PC5
PBO
PB1
PB2
PB3
PB4
PB5
PB6
PB7
21
22
23
24
25
26
27
28
37
38
39
J
2
5
29
30
31
32
33
34
35
36
I/O
Both
I/O
and
RAM
are
addressed
as data
memory
Writing a
bit
to
P27
determines whether
RAM
or I/O
is
to
be accessed
ADDING A DATA
MEMORY AND
I/O
EXPANDER
5-9