Transcript Subject Code : 3330705 Name Of Subject : Microprocessor and assembly language programming Name of Unit : Instruction cycle and Timing diagram Topic :

Subject Code : 3330705
Name Of Subject : Microprocessor and assembly language
programming
Name of Unit : Instruction cycle and Timing diagram
Topic : Instruction cycle
Name of Faculty : H.M.Avaiya & N.D.Dhameliya
Name of Students: (i) SAINI SHIVANISINGH J(091)
(ii) PANDYA DHVANIBEN D(092)
Instruction Cycle
 The microprocessor primarily
performs four operations as
listed below:
1.Memory read-to read data from
memory
2.Memory write-to write data into
memory
3.I/O read-to take data from input
device
4.I/O write-to send data from output
device
 Example:Let us consider the timing and execution of MOV A , B
instruction stored in the program memory.
This example is for 1 bit instruction.
op code fetch
Memory location
Instruction
Machine code
2000h
MOV A, B
78h
In this opcode fetch four T-state are used.
T-state:- each operation of the microprocessor is
performed in synchronization with the internal clock.
One clock pulse is called T-state.
ALE:
 It stands for Address Latch Enable.
 when it is high it indicates address and when it is
low it indicates data and opcode.
A8-A15:
It indicates higher order address.
In this cross is indicates the muitibit line is given.
In this example higher order address is 20h.
AD7-ADO:
It is the multiple line to data/add line.
 so for this example ooh is the lower order address and
78h is op code.
IO/M:
In op code fetch IO/M is
IO/M=0
S1=1
S2=2
Example:
Let us consider the timing and execution of
MVI A , FFh instruction stored in program
memory.
Memory location
Instruction
Machine code
2000h
2001h
MVI A , FFh
3Eh
FFh
When 2 byte instruction is given draw op
code fetch and memory read together.
Memory read AND memory write:
 In
memory read cycle store the data from memory.
MEMR signal enable the memory device for read
operation .
The memory write operation is also very similar to
memory read operation except it uses WR signal to
generate MEMW signal as shown in figures.
The RD and WR signals are used with IO/M = 1 to
generate IOR and IOW control signals required to
complete the I/O read and I/O write operation.
THANK YOU