w77e58 Winbond Electronics Corp America, w77e58 Datasheet - Page 29

• Manufacturer Part Number: w77e58
• Description: 8 Bit Microcontroller
• Manufacturer: Winbond Electronics Corp America

B REGISTER
B.7-0:The B register is the standard 8052 register that serves as a second accumulator.
EXTENDED INTERRUPT PRIORITY
EIP.7-5:Reserved bits.
PWDI: Watchdog timer interrupt priority.
PX5:
PX4:
PX3:
PX2:
INSTRUCTION
The W77E58 executes all the instructions of the standard 8032 family. The operation of these
instructions, their effect on the flag bits and the status bits is exactly the same. However, timing of
these instructions is different. The reason for this is two fold. Firstly, in the W77E58, each machine
cycle consists of 4 clock periods, while in the standard 8032 it consists of 12 clock periods. Also, in
the W77E58 there is only one fetch per machine cycle i.e. 4 clocks per fetch, while in the standard
8032 there can be two fetches per machine cycle, which works out to 6 clocks per fetch.
The advantage the W77E58 has is that since there is only one fetch per machine cycle, the number
of machine cycles in most cases is equal to the number of operands that the instruction has. In case
of jumps and calls there will be an additional cycle that will be needed to calculate the new address.
But overall the W77E58 reduces the number of dummy fetches and wasted cycles, thereby improving
efficiency as compared to the standard 8032.
External Interrupt 5 Priority. 0 = Low priority, 1 = High priority.
External Interrupt 4 Priority. 0 = Low priority, 1 = High priority.
External Interrupt 3 Priority. 0 = Low priority, 1 = High priority.
External Interrupt 2 Priority. 0 = Low priority, 1 = High priority.
Mnemonic: EIP
Mnemonic: B
Bit:
Bit:
B.7
7
7
-
B.6
6
6
-
- 29 -
B.5
5
5
-
PWDI
B.4
4
4
Preliminary W77E58
Publication Release Date: March 1999
PX5
B.3
3
3
Address: F0h
PX4
B.2
Address: F8h
2
2
PX3
B.1
1
1
Revision A1
PX2
B.0
0
0