13211631 what is microprocessor

8/8/2019 13211631 What is Microprocessor

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WHAT IS MICROPROCESSORWHAT IS MICROPROCESSOR ??

A Microprocessor is a multipurpose, programmable, clockA Microprocessor is a multipurpose, programmable, clock--driven, registerdriven, register--based electronic device that reads binary instruction from a storage devicebased electronic device that reads binary instruction from a storage devicecalled memory, accepts binary data as input, process this input datacalled memory, accepts binary data as input, process this input dataaccording to the instruction that have been read and then provides resultsaccording to the instruction that have been read and then provides resultsobtained from this processing as output.obtained from this processing as output.

So microprocessor is a programmable device that has computing andSo microprocessor is a programmable device that has computing and

decisiondecision--making capability. Hence it plays a significant role in themaking capability. Hence it plays a significant role in thefunctionality of industrial societies.functionality of industrial societies.

This programmable logic device can be used to control various processesThis programmable logic device can be used to control various processesand devices. The products that use microprocessor for controlling itsand devices. The products that use microprocessor for controlling itsvarious processes are calledvarious processes are called MicroprocessorMicroprocessor-- based products.based products.

When microprocessor is used in the embedded form of a larger system andWhen microprocessor is used in the embedded form of a larger system andit works as the central processing unit of a computer ,then it is calledit works as the central processing unit of a computer ,then it is calledmicrocomputer .The communications and operations in the microprocessorsmicrocomputer .The communications and operations in the microprocessorsare based on the binary numbers via 0,1.These are called Bitsare based on the binary numbers via 0,1.These are called Bits..


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Each microprocessor have a fixed set of instructions which have differentEach microprocessor have a fixed set of instructions which have differentbinary patterns .This fixed set of instructions is calledbinary patterns .This fixed set of instructions is called machine languagemachine languageof a microprocessor .These binary instructions are given some abbreviatedof a microprocessor .These binary instructions are given some abbreviated

names so that human being can easily understand and use the instructions.names so that human being can easily understand and use the instructions.These abbreviated names are calledThese abbreviated names are called mnemonicsmnemonics and the complete Set ofand the complete Set ofmnemonics of a microprocessor is called itsmnemonics of a microprocessor is called its assembly languageassembly language..


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The definition of a microprocessor as illustrated above can be shownThe definition of a microprocessor as illustrated above can be showndiagrammatically in figure 1.1.diagrammatically in figure 1.1.


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Thus microprocessor is a device that can be instructed to perform someThus microprocessor is a device that can be instructed to perform somegiven task within its capability. The memory is like the pages of a notebookgiven task within its capability. The memory is like the pages of a notebookwhich is used to store the instructions given by the user. The user gives thewhich is used to store the instructions given by the user. The user gives the

instructions as well as data (on which the instructions have to be operated)instructions as well as data (on which the instructions have to be operated)using the input devices which are stored in the memory. The input devicesusing the input devices which are stored in the memory. The input devicescan be a keyboard or simple switches. After getting the input from usercan be a keyboard or simple switches. After getting the input from usermicroprocessor reads the instructions from the memory and processes datamicroprocessor reads the instructions from the memory and processes dataaccording to these instructions .The result is then displayed using an outputaccording to these instructions .The result is then displayed using an outputdevice. The output device here can be any sevendevice. The output device here can be any seven --segment displays whichsegment displays whichuses LEDs (LightEmitting Diodes) or printer.uses LEDs (LightEmitting Diodes) or printer.


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INTERNAL MICROPROCESSOR ARCHITECTUREINTERNAL MICROPROCESSOR ARCHITECTURE


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Here we will discuss the internal architecture of Intel 8086 microprocessor.Here we will discuss the internal architecture of Intel 8086 microprocessor.It was first 16It was first 16--bit microprocessor developed by Intel Company in 1976. It isbit microprocessor developed by Intel Company in 1976. It iscalled 16called 16--bit microprocessor because it has 16bit microprocessor because it has 16--bit data bus. However it hasbit data bus. However it has

2020--bit address bus. Because of this large size of address bus it can addressbit address bus. Because of this large size of address bus it can addressup 1MB of memory.up 1MB of memory.

After the development of 8086 microprocessor, Intel launch a series ofAfter the development of 8086 microprocessor, Intel launch a series of86s microprocessor like 80186, 80286, 80486 etc. Which are 3286s microprocessor like 80186, 80286, 80486 etc. Which are 32--bitsbitsprocessors. This microprocessor is very fast as compared to the old ones,processors. This microprocessor is very fast as compared to the old ones,as microprocessor Whey have reduced the CPU idle time in system. Theseas microprocessor Whey have reduced the CPU idle time in system. These

microprocessor can execute can execute the instructions in the speed rangemicroprocessor can execute can execute the instructions in the speed rangeof thousand operations per second.of thousand operations per second.

A microprocessor execute a program by performing the followingA microprocessor execute a program by performing the followingactivities again and againactivities again and again --

(a) Fetch the next instruction from memory(a) Fetch the next instruction from memory(b) Read operand(b) Read operand

(c) Execute instruction(c) Execute instruction(d) Write result(d) Write result


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In the microprocessor before Intel 8086, these steps were performing serially. ButIn the microprocessor before Intel 8086, these steps were performing serially. Butthe architecture of 8086 performs these steps by allocating them to separatethe architecture of 8086 performs these steps by allocating them to separateprocessing units .These are:processing units .These are:--

11. Execution. Execution unit (EU)unit (EU)

2. Bus Interface unit (BIU)2. Bus Interface unit (BIU)

Execution unitExecution unit is the unit which executes the instructionsis the unit which executes the instructions and busand businterfaceinterface unit has the responsibilities of fetching instructions, read operands, writingunit has the responsibilities of fetching instructions, read operands, writingresult.result.

These two units operate independently and in most of circumstances areThese two units operate independently and in most of circumstances areable to extensively overlap instruction with fetch executions operation. In theseable to extensively overlap instruction with fetch executions operation. In thesecases, the times normally required to fetch instructions disappears because of thecases, the times normally required to fetch instructions disappears because of theexecution unit executing instructions that have already been fetched by the BIU.execution unit executing instructions that have already been fetched by the BIU.


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However it must be noted that execution unit has no connection with theHowever it must be noted that execution unit has no connection with thesystem bus. It obtains instructions from queue maintained by the BIU.system bus. It obtains instructions from queue maintained by the BIU.

Similarly, when an instruction requires access to memory or to a peripheralSimilarly, when an instruction requires access to memory or to a peripheraldevice, the EU requests the BIU to obtain or store the data. Execution unitdevice, the EU requests the BIU to obtain or store the data. Execution unitmanipulate the addresses in only 16manipulate the addresses in only 16--bit wide .Then BIU performs thebit wide .Then BIU performs theaddress relocation which gives the EU access to the full megabyte ofaddress relocation which gives the EU access to the full megabyte ofmemory space.memory space.

So BIU performs all the bus operations for the EU. Upon the demand ofEUSo BIU performs all the bus operations for the EU. Upon the demand ofEU

it serves the data between the CPU and memory or I/O devices. BIU alsoit serves the data between the CPU and memory or I/O devices. BIU alsohave an internal RAM array calledhave an internal RAM array called Instruction Stream Queue .Instruction Stream Queue .During theDuring thetime when EU is busy in executing the instructions, BIU fetches moretime when EU is busy in executing the instructions, BIU fetches moreinstructions from the memory and store these instruction stream queue.instructions from the memory and store these instruction stream queue.This queue can store up to 6 instruction bytes at a time.This queue can store up to 6 instruction bytes at a time.


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Various memory registers in an 8086 microprocessor can be divided intoVarious memory registers in an 8086 microprocessor can be divided intofollowing categories.following categories.

1. General Purpose Registers1. General Purpose Registers

2. Pointer registers2. Pointer registers

3. Segment Registers3. Segment Registers

8086 microprocessor also have some of flags. All these will be8086 microprocessor also have some of flags. All these will be

explained in detail now.explained in detail now.


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1.2.1.1.2.1. General Purpose RegistersGeneral Purpose RegistersVarious general purposes registers areVarious general purposes registers are--(i) Accumulator Register (AX)(i) Accumulator Register (AX)

(ii) Base Register (BX)(ii) Base Register (BX)(iii) Counter Register (CX)(iii) Counter Register (CX)(iv) Data Register (DX)(iv) Data Register (DX)

These registers are 16These registers are 16--bit registers. They can either work as 16bit registers. They can either work as 16-- bit registersbit registersor as two 8or as two 8--bit registers as shown belowbit registers as shown below--

ACCUMULATORACCUMULATOR -- AXAX is usually constantly changing throughout any program. Thisis usually constantly changing throughout any program. Thisis considered to be one of the most useful register ,8086 also have some other hardis considered to be one of the most useful register ,8086 also have some other hard--wired connection of AX with other registers like the XLAT (transaction) instruction ofwired connection of AX with other registers like the XLAT (transaction) instruction ofregister BX uses AL. The division ,multiplication ofDX also uses AL. The instructionsregister BX uses AL. The division ,multiplication ofDX also uses AL. The instructionsfor coping part of the flags registers to / from AH are also available.for coping part of the flags registers to / from AH are also available.

BASE REGISTERBASE REGISTER -- BX is mainly used for general storage, but it can also be usedBX is mainly used for general storage, but it can also be usedfor accessing memory. It is the only general purpose registers that can also works asfor accessing memory. It is the only general purpose registers that can also works as

a pointer .However unlike SI and DI registers, it does not work with rep prefix.a pointer .However unlike SI and DI registers, it does not work with rep prefix.


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COUNTER REGISTERCOUNTER REGISTER -- CX is mainly used for general storage , but inCX is mainly used for general storage , but in

addition to this it can also be used as an iteration counter .The Rep prefix,addition to this it can also be used as an iteration counter .The Rep prefix,loop instruction shift and rotate instructions all take counts passed in CX.loop instruction shift and rotate instructions all take counts passed in CX.

DATA REGISTERDATA REGISTER-- DXDX is truly used as data storage register only .DX isis truly used as data storage register only .DX isalso used in division instructions .After 16also used in division instructions .After 16 --bit division, the remainder isbit division, the remainder isplaced in DX. The DX registers also used with AL register and the in/outplaced in DX. The DX registers also used with AL register and the in/out

instructions to specify the port numberinstructions to specify the port number

13211631 what is microprocessor

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