W79E225A Datasheet, PDF (177/200 Pages) Winbond – 8-bit Microcontroller

Preliminary W79E225A/227A Data Sheet
P43AH, P43AL:
The Base address registers for comparator of P4.3. P43AH contains the high-order byte of address;
P43AL contains the low-order byte of address.
PORT 4
Bit:
7
-
Mnemonic: P4
P4.3-0
6
5
4
3
2
-
-
-
P4.3
P4.2
Port 4 is a bi-directional I/O port with internal pull-ups.
1
0
P4.1
P4.0
Address: A5h
PORT 4 CHIP-SELECT POLARITY
Bit:
7
6
5
4
3
2
1
0
P43INV P42INV P42INV P40INV -
PWDNH RMWFP PUP0
Mnemonic: P4CSIN
Address: A2h
P4xINV
The active polarity of P4.x when it is set as a chip-select strobe output. High =
Active High. Low = Active Low.
PWDNH
Set PWDNH to logic 1 then ALE and PSEN will keep high state, clear this bit to logic
0 then ALE and PSEN will output low during power down mode.
RMWFP
Control Read Path of Instruction “Read-Modify-Write”. When this bit is set, the read
path of executing “read-modify-write” instruction is from port pin otherwise from
SFR.
PUP0
Enable Port 0 weak pull up.
- 177 -
Publication Release Date: December 14, 2007
Revision A2.0