Intel MCS48 User Manual page 128

APPLICATION
EXAMPLES
+5V
,40
,,26
,20
INPUT
V
CC
Vqd
Vss
XTAL
1
8049
8048
8748
8035*
8039*
TO
T1
l"NT
ALE
PSEN
PROG
WR
RD
P10
P11
P12
P13
P14
P15
P16
P17
P20
P21
P22
P23
P24
P25
P26
P27
DBO
DB1
DB2
DB3
DB4
DB5
DB6
DB7
22
23
24
_,
35
36
37
33
-
I/O
*EA
= 5V
FOR
8035/8039
CAN
BE SUPPLIED
BY SYSTEM
RESET
OR PORT
LINE
OF
8048
40
20
1
Vcc
Vqd
Vss ce
A8
A9
A10
ADO
AD1
AD2
AD3
AD4
AD5
AD6
AD7
fOR
lOW
RD
ALE
CE
RESET
8355
8755A
2Kx8
ROM
JI
I
3
I
6
"="
NC
NC
PAO
PA1
PA2
PA3
PA4
PA5
PA6
PA7
PBO
PB1
PB2
PB3
PB4
PB5
PB6
PB7
I/O
External I/O ports are
addressed
as data
memory
PA=00 PB=01
If
the
8048s
internal
Program
Memory
is
used
this
configuration
will
result
in
the
upper 1K
of
external
memory
being
addressed
before the lower
1K.
Inverting
A10
will
correct
this
if
necessary. This
inversion
is
not
necessary
if
the
8049
is
used.
ADDING
A
PROGRAM MEMORY AND
I/O
EXPANDER
5-8