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6.2.4 Address Control Register (ADRCR)
ADRCR is an 8-bit readable/writable register that enables address output on bus lines A23 to A21.
Bit
Initial value
Read/Write
Initial value
Read/Write
7
A
23
E
1
—
1
R/W
6
A
22
E
1
—
1
R/W
5
A
21
E
1
—
1
R/W
4
—
1
—
1
—
3
—
1
—
1
—
0
—
0
R/W
0
R/W
2
—
1
—
1
—
1
—
1
—
1
—
Address 23 to 21 enable
These bits enable PA
6
to
PA
4
to be used for A
23
to
A
21
address output
Reserved bits
Modes
1 and 5 to 7
Mode 3
ADRCR is initialized to H'FE by a reset and in hardware standby mode. It is not initialized in
software standby mode.
Bit 7—Address 23 Enable (A
23
E): Enables PA
4
to be used as the A
23
address output pin. Writing
0 in this bit enables A
23
address output from PA
4
. In modes other than 3 and 6 this bit cannot be
modified and PA
4
has its ordinary input/output functions
Bit 7
A
23
E
Description
0
PA
4
is the A
23
address output pin
1
PA
4
is the PA
4
/TP
4
/TIOCA
1
input/output pin
(Initial value)
Bit 6—Address 22 Enable (A
22
E): Enables PA
5
to be used as the A
22
address output pin. Writing
0 in this bit enables A
22
address output from PA
5
. In modes other than 3 and 6 this bit cannot be
modified and PA
5
has its ordinary input/output functions.
Bit 6
A
22
E
Description
0
PA
5
is the A
22
address output pin
1
PA
5
is the PA
5
/TP
5
/TIOCB
1
input/output pin
(Initial value)