W77C58 Datasheet, PDF (25/71 Pages) Winbond – 8 BIT MICROCONTROLLER

Preliminary W77C58
INSTRUCTION
The W77C58 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 W77C58, each machine
cycle consists of 4 clock periods, while in the standard 8032 it consists of 12 clock periods. Also, in
the W77C58 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 W77C58 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 W77C58 reduces the number of dummy fetches and wasted cycles, thereby improving
efficiency as compared to the standard 8032.
Table 2. Instructions that affect Flag settings
Instruction
ADD
ADDC
SUBB
MUL
DIV
DA A
RRC A
RLC A
SETB C
Carry
X
X
X
0
0
X
X
X
1
Overflow
X
X
X
X
X
Auxiliary Carry
X
X
X
Instruction
CLR C
CPL C
ANL C, bit
ANL C, bit
ORL C, bit
ORL C, bit
MOV C, bit
CJNE
Carry
0
X
X
X
X
X
X
X
A "X" indicates that the modification is as per the result of instruction.
Overflow Auxiliary Carry
Table 3. Instruction Timing for W77C58
Instruction
HEX
Op-Code
Bytes
NOP
ADD A, R0
ADD A, R1
ADD A, R2
ADD A, R3
ADD A, R4
ADD A, R5
00
1
28
1
29
1
2A
1
2B
1
2C
1
2D
1
W77C58
Machine
Cycles
1
1
1
1
1
1
1
W77C58
Clock
Cycles
4
4
4
4
4
4
4
8032
Clock
Cycles
12
12
12
12
12
12
12
W77C58 vs.
8032 Speed
Ratio
3
3
3
3
3
3
3
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Publication Release Date: September 1999
Revision A1