MicroProcessor



MicroProcessor Unit 1 !!

1. What is a Mricroprocessor? Elaborate your answers with examples.
	The microprocessor is the central processing unit or cpu of a micro computer.it is the heart of the
computer.
A microprocessor is an electronic component that is used by a computer to do its work. It is a central processing unit on a single integrated circuit chip containing millions of very small components including transistors, resistors, and diodes that work together. Microprocessors help to do everything from controlling elevators to searching the Web. Everything a computer does is described by instructions of computer programs, and microprocessors carry out these instructions many millions of times a second.c96




2. Draw the Architechture of Microprocessor INTEL 8085. Introduce its three sections.
	INTEL 8085:
It is an 8 bit Nmos microprocessor.it is an forty pin IC(integrated circuit) package fabricated on
a single LSI (Large scale Integration) chip.
It uses a single +5 volt d.c.(Direct Current) supply for its operation.It clock spee is 3 mhz.It
consists of 3 main sections.
1-Arithmetic Logic Unit(ALU)
2-Timing and control unit
3-Several Registers
Arithmetic Logic Unit:
It performs various arithmetic an logical operations like aition,substraction,logical an
,xor,or,not,increment etc.
Timing and control unit:
It generates timing an control signals hich are necessary for the execution of the instructions.it
controls the ata flo beteen cpu an peripherals.
Several Registers:
Registers:-it is a collection of flip flops use to store a binary word.they are used by the
microprocessor for the temporary storage and manipulation of data and instructions.
8085 has the following registers:
1-8 bit accumulator i.e. register A
2-6 8 bits general purpose registers i.e. B,C,D,E,H,L
3-one 16 bit regiser i.e.stack pointer
4-16 bit Program counter,Status register,Temporary register,Instruction Register.




3. Write short notes on all the Registers of INTEL 8085
	The regiser A holds the operands during program execution.
There are 6 8 bits general purpose registers B,C,,E,H,L are to handle 16 bit data.two 8 bit registers can be combined. This is called register pair. 
Valid pair of 8085 are : B- C,-E,H-L.The H-L. pair is used to as address memory location.B-C,D-E are used for access another function.
STACK POINTER:
Stack is a sequence of memory location defined by the programmer in LIFO function.That is last
Element to be placed on the stack is first one is to removed .The stack pointer contain the address
of the stack cup.
PROGRAM COUNTER:
It is the address of the next instructions to be executed.
INSTRUCTION REGISTER:
It holds a copy of the current instruction until it is decoded.
STATUS REGISTER:
It contains the status flags of 8085 microprocessor.
TEMPORARY REGISTER:
It is used to store intermediate results and for intermediate calculations.
STATUS FLAGS:
It is a set of 5 flip-flops
i. Carry Flag(Cs)
ii. Sign Flag(S)
iii. Zero Flag(Z)
iv. Parity Flag(P)
v. Auxilarity carry flag(Ac)
Carry Flag:
It holds carry out of the resulting from the execution of an arithmetic operation.
If there is a carry from addition or a borrow from substraction or comparision,the carry flag is
said to 1 ortherwise it is 0.
Sign Flag:
It is set to 1 if the MSB of the result of an arithemetic or logical operation is 1 ortherwise it is 0.Zero Flag:
It is said to 1 if the result of an arithmetic or logical operation is zero.for non zero result,it is 0.
Parity Flag:
It is set to 1 when the the result of the operation contains even no.of 1& it is set to 0 if there are
odd no.of 1.
Auxilary Carry Flag:
It holds carry from bit 3 to A resulting from the execution of an arithmetic operation.If there is a
carry from bit 3 to 4,the AC flag is set to 1 ortherwise it is 0.
Program Status Word(PSW):
It is a combination of 8-bits where five bits indicates the 5 status flags & three bits are undefined.
Psw and the accumulator treated as a 16 bit unit for stack operation.BUS ORGANISATION:
INTEL 8085 is a 8 bit micro processor.its data bus is 8 bit wide .8 bit of data can be transmitted
in parallel form.or to the microprocessor.
Address bar is 16 bit wide as memory address are of 16 bit.8 msb is the address are
transmitted by on A8-A15.8 LSB is is the address are transmitted by the data bus AD0-AD7.The
address or data bus transmits data & address at different moments.it can transmits data or address
at a time.




4. Explain the status Signal S0, S1 (output) in Intel 8085
	This is an output status signal used to give info of operation to be performed with ... The S0 and S1 lines specify 4 different conditions of 8085 machine cycles.
These signals are used to identify the type of current operation.




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