Micro-Processor:

A micro-processor is a multi-purpose, programmable, clock driven, register based, electronic device that reads binary instructions from a storage devices called memory and accepts binary data as inputs and processes data according to those instructions and provides results as output.

Microprocessor operates in binary 0 and 1 known as bits which are represented in terms of electrical voltage in the machine. That means 0 represents low voltage and 1 represents high voltage level. Each microprocessor and processes a group of bits called the word and microprocessor are classified according to their word length such as 8 bit microprocessor with 8 bit word, 32 bit microprocessor with 32 bit word, etc.

Fig: Microprocessor

Terms used:

·         C.P.U:           C.P.U  which consists of A.L.U and C.U

·         MICROPROCESSOR:                                Single chip containing all units of C.P.U.

·         MICRO PROCESSING UNIT:                  M.P.U which is complete processing unit with the necessary control signals.

·         MICRO CONTROLLER:             Single chip containing of M.P.U, memory, I/O, interfacing circuits.

·         MICRO COMPUTER:                             Computer having microprocessor as C.P.U.

MICRO COMPUTER:

                The micro processor is a digital integrate circuit device that can be programmable with a series of instructions to perform specific functions on data. In its basic from, a microprocessor consists of 3 elements:-

·         A.L.U(Arithmetic Logic Unit)

·         R.U(Register Unit)

·         C.U(Control Unit)

# A.L.U:

                It performs arithmetic operations such as addition, subtraction, multiplication, and division and logical operations such as NOT, AND, OR, XOR, etc.

#Register Unit:

                During an execution of a program, data are temporally stored in any of the many registers that make up this unit.

 #Control Unit:

                It provides the timing and control signals for getting data into and out of the microprocessor. Microprocessor has 3 buses which are used for information transfer internally and externally.

                These buses are:-

·         Address Bus

·         Data Bus

·         Control Bus

When microprocessor is connected to a memory device and provides a means of transferring data to and from the outside world, it is said to have a microprocessor. It is a digital computer which C.P.U. consists of a microprocessor. Once, less powerful then larger computer, micro computers are now as powerful as mini computers and super computers. This is due to the growing of the processing power of each successive generation of microprocessor, plus the addition of mainframe computer features to the chip, such as floating point of mathematic, computation, hardware, memory management and multi-processing support.

Fig:- Block diagram of Micro-Computer

In any micro computer, four ports and buses are found. They are

·         Input ports:
# it converts human codes into computer codes
# provides an interface between the input devices and C.P.U.

·         Microprocessor/C.P.U :
#contains the control unit and arithmetic logic unit
#organizes the correct sequences of processes
#performs all the mathematical and logical operations of the systems

·         Memory:
#stores the instruction and data
#needed during processing for execution of programs or commands

·         Output ports:
#converts computers codes into human codes
#provides interface between the C.P.U. and output devices

·         Address Bus:
#used by the C.P.U. to select memory location
#used by I/O ports to be active at a given time

·         Data Bus:
#where all the data and instructions travel from the C.P.U. to the memory  or any I/O ports or vice versa

·         Control Bus:
#used by the C.P.U. to inform the memory or I/O port that it is ready to perform, data transfer with read or write operation

Evolution of MICRO-PROCESSOR:

                The evolution of micro-processor development of integrated circuit technology through SSI, VLSI, and ELSI

Date	Micro Processor	Data Bus	Address Bus	Memory
1971	8004	4 bit	10 bit	4 Kb
1972	8008	8 bit	14 bit	16 Kb
1973	8080	8 bit	16 bit	64 Kb
1976	8085	8 bit	16 bit	64 Kb
1978	8086	16 bit	20 bit	1 MB
1979	8088	8 bit	20 bit	1 MB
1982	80286	16 bit	24 bit	16 MB
1985	80386	32 bit	32 bit	4 GB
1989	80486	32 bit	32 bit	4 GB
1993	Pentium	64 bit	32 bit	64 GB
1995	Pentium Pro	64 bit	36 bit	64 GB
1997	Pentium II	64 bit	36 bit	64 GB
1998	Celeron	64 bit	36 bit	64 GB
1999	Pentium III	64 bit	36 bit	64 GB
2000	Pentium IV	64 bit	36 bit	64 GB
2001	Itanium	128 bit	64 bit	64 GB
2002	Itanium II	128 bit	64 bit	64 GB
2003	Centrino/Pentium m (Wireless capability)	128 bit	64 bit	64 GB

Application of Micro-Processor:

               

1>     Embedded System:
-used in micro-controller (Roberts)

2>     Measurement and testing equipment:
-used in signal generators, oscilloswpes, counters, digital volt meter, X-ray analyzers, blood group analyzers, baby inwbator, frequency synthesizers, data acquisition system, spectrum analyzer, etc.

3>     Scientific and Engineering research

4>     Industries
-used in data monitoring system, automatic waiting, automatic batching, etc.

5>     Security system:
-used in CCTV, smart cameras, smart doors, etc.

6>     Automatic system:
-Robotic system, auto-pilot, etc.

The 8085A commonly known as 8085 micro-processor invented in 1976 by Intel, is a 8 bit general purpose micro-processor capable of addressing 64 Kb of memory. The device has 40 pins, requires of +5v single power supply and can operate with 3 MH_Z single phase clock. The main components of 8085 micro-processor are
-Array of Register
-Arithmetic Logic Unit
-Encoder/Decoder
-Timing and Control circuit
-Linked by an internal data bus

        The block diagram is shown in above figure

All parts associated in 8085 are explained as follows:

1>A.L.U:
        -it performs the computing functions and it includes the accumulator, temporary register, ALU circuits, instruction register, decoder and flag flip flop.
a>Accumulator:
        it is an 8 bit register on which all the operations depend. 8085 micro-processor is an accumulator based micro-processor. The A.L operations are performed on accumulator. When data read from input port, it first moved to accumulator and data is output to output port, it must first place in accumulator.

b>Temporary Register:
        it is an 8 bit register not accessible to the programmer. During program execution 8085 places the data into it for a brief period.

c>Instruction Register:
        it is an 8 bit register not accessible to the programmer. It receives the operation codes of instructions from internal data bus and passes to the instruction decoder which decodes so that micro-processor knows which type of operations is to be performed.

d>Register Array:

I>Scratch Pad Register:
        B, C, D, E is 8 bit register accessible for programmers. Data can be stored upon it during program execution. These can be used individually as 8 bit register or in pair B&C and D&E as 16 bit registers. Data can be directly added or transform from one to another. Their contents may be incremented or decremented and combined logically with the content of accumulator.

II>Memory Register:
        Register H and L is 8 bit registers that can be used in same manner as scratch pad registers and are used in memory operation.

III>Stack Pointer:
        It is a 16 bit register used as a memory pointer. It points to a memory location in R/W memory, called the stack. The beginning of the stack is defined by loading of 16 bit address in the stack pointer.

IV>Program Counter:
        It is used to point to the memory address from which the next instruction is to be fetched. When an instruction byte is being fetched, the PC is incremented by one point to the next memory location.

e>Flag:
                It consists of five flags and each holds the status of different states, separately known as flag register and each flip flop is known as flag. 8085 can set or reset 1 or more flags and are Carry, Sign, Zero, Auxiliary Carry and Parity. The state of the flags indicates the result of arithmetic and logic operations which in turn can be used for decision making processes. Different flags are described as:

I>Carry:

                In the last ALU operation generates a carry, it status will be 1 other wise 0. It can handle the carry or borrow from 1 word to another.

II>Zero:

                If the last ALU result is 0, its status will be 1 otherwise 0. It often used in loop control and in searching for particular data value.

III>Sign:

                If the most significant bit (MSB) of last ALU result is negative that is 1, its status will be 1 otherwise 0.

IV>Parity:

                If the last ALU result is even for even parity and odd for odd parity, its status will be 1 otherwise 0.

V>Auxiliary Carry:

                If the last ALU operation generates the carry from the lower half word (lower nibble), its status will be 1 otherwise 0. It is used for performing BCD arithmetic.

2>Timing and Control Unit:
                This unit synchronizes all the micro-processor units with the clock and generates the control signals necessary for communication between micro-processor and peripheral devices.

3>Interrupt Control:
                Various interrupt control signals are used to interrupt a program execution.

4>Serial I/O Control:
                The two serial I/O control signals are used to implement the serial data transmission.