N79E875 Datasheet, PDF (70/192 Pages) List of Unclassifed Manufacturers – 8-BIT MICROCONTROLLER

Preliminary N79E875 Data Sheet
8 INSTRUCTION
The N79E875 series execute all the instructions of the standard 8052 family. The operations of these
instructions, as well as their effects on flag and status bits, are exactly same. However, the timing of
these instructions is different in two ways. Firstly, the machine cycle is four clock periods, while the
standard-8051/52 machine cycle is twelve clock periods. Secondly, it can fetch only once per machine
cycle (i.e., four clocks per fetch), while the standard 8051/52 can fetch twice per machine cycle (i.e.,
six clocks per fetch).
The timing differences create an advantage for the N79E875 series. There is only one fetch per
machine cycle, so the number of machine cycles is usually equal to the number of operands in the
instruction. (Jumps and calls do require an additional cycle to calculate the new address.) As a result,
the N79E875 series reduces the number of dummy fetches and wasted cycles, and therefore
improves overall efficiency, compared to the standard 8051/52.
Op-code
NOP
ADD A, R0
ADD A, R1
ADD A, R2
ADD A, R3
ADD A, R4
ADD A, R5
ADD A, R6
ADD A, R7
ADD A, @R0
ADD A, @R1
ADD A, direct
ADD A, #data
ADDC A, R0
ADDC A, R1
ADDC A, R2
ADDC A, R3
ADDC A, R4
HEX Code Bytes
N79E875
series
Machine
Cycle
N79E875
series
Clock
cycles
8032
Clock
cycles
00
1
1
4
12
28
1
1
4
12
29
1
1
4
12
2A
1
1
4
12
2B
1
1
4
12
2C
1
1
4
12
2D
1
1
4
12
2E
1
1
4
12
2F
1
1
4
12
26
1
1
4
12
27
1
1
4
12
25
2
2
8
12
24
2
2
8
12
38
1
1
4
12
39
1
1
4
12
3A
1
1
4
12
3B
1
1
4
12
3C
1
1
4
12
- 70 -
N79E875
series vs.
8032 Speed
Ratio
3
3
3
3
3
3
3
3
3
3
3
1.5
1.5
3
3
3
3
3