What Is A Microprocessor Computer Science Essay

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According to the definition in Webster," Microprocessor is the integrated circuit that contains the entire central processing of a computer on a single chip." Microprocessor is a device that integrates the function of CPU in a computer onto the semi conductor chip.

A single microprocessor mainly contains five essential parts of our computer:

Memory Unit


Control Unit

Interrupt or Execution Controller

Internal Cache

Some interesting facts on Microprocessors:

In 2003, Microprocessors worth 44 billion dollars were made. They were even sold out at the same time. Most of these microprocessors were spent on laptops and desktops.

Almost 56% of CPU's that have been sold are of 8bit microprocessor.

Similarly, less than 10% of the sold CPU's has 32bit microprocessor or more.

Microprocessors were sold mostly for house hold devices such as Television, vacuum cleaners, etc. [Stephanie 06]

So, there are different bits of microprocessors such as 16 bit microprocessor, 32 bit microprocessor, 64 bit microprocessor, and so on. Here we study about 32 bit microprocessors.

A 32 bit microprocessor is a binary file format where every basic computer data is defined on 32 bits (or 4 bytes). Now-a-days, there are different types of micro processors available in the market. Some of them are: Intel, Motorola, AMD, etc.

[Study Guide and Teacher's Note]

Her e is Microprocessor

Fig: A Mother Board

Fig: Intel Micro processor

History of 32 Bit microprocessor

Intel released the first microprocessor of 16 bits in the year 1978. 16 bit processor works with 16 bits words. These 16 bit microprocessors gave birth to 32 bit microprocessor. [History]

The development of 32 bit microprocessor started in the late 1970s but this microprocessor came to the market in the 1980s because of the Hewlett-Packard and National semiconductor. 32 bit microprocessors were very advanced as compared to previous bits of microprocessor. Similarly, 32 bit microprocessors are also known as the prototype of recent microprocessors. [abc]

Fig: Some of the few Intel Microprocessor

Bus Architecture

Bus Architecture:

What is a bus?

Bus is the communication media between two or more components of the CPU. Two or more devices are connected to a bus and a signal sent by one device is accessible for all other devices attached to the bus. Various communication pathways or line forms a bus, where every line transmits either 0 or 1. [Study Guide]

Historical Changes in Bus Architecture

Single Bus

Double Bus

3 buses Architecture

Multiplexed Architecture

Types of bus

Internal Bus:

It is also famously known as internal data bus, memory bus or system bus. This bus simply unites all the internal devices like processor and memory to the motherboard. This bus is also known as local bus as they are needed to connect to other devices. This bus is very fast and also is independent in nature. [internal]

External Bus:

External bus is another type of bus which simply inter connects a computer with other peripheral devices. For example: USB port, IEEE 1394, etc. [external]. There are six various kinds of external bus are found inside our PC. These bus are usually have pins covered in the inner channel. Similarly, some of the external bus can even be made up of gold or tin.

Fig: Internal and External Bus

System Bus normally comprises of 50-100 different lines where every line are split amongst Data, Control and Address Lines. The width of the bus is derived by the total number of lines of the system bus. Typical physical arrangement of system bus is:

Various parallel electrical conductors.

By adding more boards, our system can be extended.

Similarly, by replacing certain current boards, the bad section can be replaced or removed. [comp 2000]

Most of today's bus structures are derived from Von Neumann Computer Model. This model has large random access memory so effectiveness is maintained and is faster too. [Study Guide]

The Von Neumann Architecture is based in three concepts:

Instructions as well as data are stored in read-write memory.

The content of this memory are addressable by locating without looking at the data in it.

Execution forms in sequential fashion from one instruction to next. [Comp 2000]

There are three major components of this model. They are:

Central Processing Unit (CPU)

Input/output (I/O) Components


Categories of Bus:

Similarly, there are three kinds of bus in this model. They are:

Data Bus/Lines

Address Bus/Lines

Control Bus/Lines

Data Bus:

Data Bus is the bus that gives a way or track for changing data among system components. [Comp 2000]. Here system performance is determined by the width if the data bus.

Basically, a data bus comprises of 8, 16 or 32 parallel signal lines. The data buses are bi-directional in nature. Most of the components of the system will have their output joined with the data bus, but only one device or component at a time will have its output enabled. [Bus]

Address Bus:

The purpose of address bus is to allocate data's source and target in the data bus. Here the width of address bus allocates the memory power of our system. Higher the width, the more will be the memory capacity and vice versa. [Study Guide]

Generally, Address Bus comprises of 16, 20, 24 or 30 parallel lines. The CPU sends the address of the memory location that is to be written to or read from via these lines. The number of address lines denotes the amount of memory location that CPU addresses. Mathematically, if a CPU has suppose n address lines then it denotes that there are 2n memory locations. A 32 address lined CPU can address 4,294,967,296 memory locations. When a CPU sends data from or writes data to a port, it sends port address out on the address bus. [Bus]

Control Bus:

It is used to control the access to and the use of data and address lines. The command and timing information between system modules is transmitted via control signals where timing signals denotes the validation of data and information address. Similarly, a command signal indicates the tasks to be operated. [Study guide]

Generally, it is of 4 to 10 parallel lines. To activate the outputs of addressed memory devices or port devices, the CPU transmits signal on the Control Bus. Typical Control Bus includes:

Memory read and memory write

I/O Read and I/O Write

Transfer ACK

Bus Grant and Bus Request

Interrupt ACK and Interrupt Request


Reset [Bus]

Fig: Bus Structure

Example of 32 bit microprocessor:

Intel Xeon Microprocessor:

Intel created its Xeon microprocessor in the year 2001. The cache memory of this memory was 256 KB where as processor package style was Organic Land Grid Array 603. 400 MHz was its System Bus clock and had SSE2 SIMD extensions. Generally, these microprocessors had very high performance as compared to other microprocessor at that time.

Advantages of Bus Architecture:

The devices that share same bus standard can be shifted between computer system.

New devices can be added, modified or removed easily.

Cost effective.

By the use of bus architecture, sharing of single set of wires can be done in many ways.

By portioning the design, the difficulty faced in computer system can be managed.

Hardware Support


Memory Management

Hardware Support to Memory Management:

To operate the computer effectively, the memory of the CPU must be managed properly. Memory management of today's modern systems is very hard. Failure in the proper management of memory results sluggish performance, various bugs and can also result in various kinds of viruses. So, memory must be managed in proper and systematic way. [mgmt11]

Memory Hierarchy:

The most important part of a computer is its memory unit. All the programs and data are stored in this memory unit. The main memory which directly links with the CPU is known as main memory. Similarly, the devices which have backup storage are known as auxiliary memory. Magnetic disks and tapes are the most generally used auxiliary memory device; as they are used for storing huge data files, system programs, and other backup information. In the main memory, the data that are always required by processor are stored. But the information that has been stored in auxiliary memory can be moved to main memory when it is needed. The memory hierarchy system consists of all devices that are currently available in our computer system. [CSA]

Memory management Unit (MMU):

It is the component of hardware which manages virtual memory system.

It is a part of CPU. But in some architecture, it is located in separated in different chip.

Small quantity of memory is included in MMU, which makes a table which matches virtual addresses with physical addresses.

The table is also known as Translation Look-aside Buffer (TLB). [MMU]

Need for memory management:

To present suitable concept for programming.

To assign limited memory resources amongst opposing processes to increase performance with nominal overhead.

Ways to manage memory

Cache Memory

Virtual Memory




Cache Memory :

It is very fast memory which is made in CPU or can be situated in another chip.

CPU uses cache memory to pile up actions which are continuously needed to execute programs leading in increase of system's speed.

For the transfer of data, the CPU does not have to use motherboard's system bus with the use of cache memory.

Various levels of cache are there like Level 1 (L1) cache, L2 cache and L3 cache. [cache]


Average memory access time is improved with the help of cache memory.

Similarly, the entire implementation time of a program is also reduced.

Data can be accessed faster with the main memory.

Even if the memory is busy with other operations, cache memory can still access data and instruction. [adv]

Virtual Memory :

It is a memory management method invented for multitasking kernels.

Generally, computer shifts data in an empty space in the HDD drive, once RAM memory is used up. So, by increasing the size of virtual memory, we increase the empty spaces making the performance faster.


Main memory is used much more efficiently.

The programs that are bigger than the main memory can still be executed.

Paging :

Paging is the method employed by virtual memory so that data can be retrieved easy as soon as possible, anytime when needed. By the use of paging, the system copies few amount of pages from our storage device to our memory. If the program requires a page that is not available in the memory, the system simply copies the required page in the memory and copies other age back to the disk.


Memory allocation will be easy.

Chunks of a program can be easily swapped out.

There will be no problem in doing External Fragmentation. [paging]

Fig: Paging

Segmentation :

Segmentation is the technique that is used to allocate main memory by segments like file, data, module, etc. Segments are variable size of blocks. Segment size also varies from 2^16 bytes till 2^32 bytes. The main objective of Segmentation is to simplify and modify the illustration of an image into somewhat more meaningful and helps in analyzing easily. [study guide]


It simplifies and handles the growing data structures.

Programs can be recompiled and modified separately.

Data can be shared among processes.

Protection can be better. [adv1]

Fig: Segmentation

Pipeline Architecture

Pipeline Architecture:


Pipelining is the helpful method of arranging parallel activity in a computer. Generally, pipelining is known as assembly-line operation. In this method, the output of one element is the input of the next element.

Stages of Pipeline

IF - Instruction cache fetch

RF - Register fetch

EX - Execution

DC - Data cache fetch

WB - Write back

Fig: Pipeline Stages

Superscalar Pipeline:

It is the method in which, CPU is implement in such a way that one instruction will be concluded at a time.

A Superscalar known as the CPU architecture that executes an outline of parallelism called instruction level parallelism in a single processor.

Duplication of some parts of CPU is involved in this method.

More than one instruction is executed in a superscalar processor during a clock cycle.

These days microprocessor generally have 2 to 6 instruction per cycle in each pipeline stage.

Fig: Superscalor Pipeline

Examples of Superscalar

Fetching of several instruction at same time.

Decoding of several instruction at same time.

Operation like add and multiply at same time.

Performing load action while executing ALU action.

Possible Pipelines

Instruction Pipeline:

These pipelines are used to permit overlapping implementation of numerous instructions having the similar circuitry. In General, Circuitry is separated in various stages consisting decoding of instruction, arithmetic and fetching register stages. One instruction is processed at a time in each stage.

Graphics Pipeline:

This pipeline is found mostly in graphic cards. It comprises of various arithmetic units which executes several stages of operations like calculation of light and color, rendering, etc.

Software Pipeline:

It is used to write commands such that the result of a operation is the input of the next operation. Example: UNIX command.

Working Mechanism of pipeline

Fig: Working mechanism

Advantages of pipelining:

With the use of pipelining, cycle time of processor is reduced in such a way that the instructions execution rates are operated at maximum speed.

By adding up additional circuitry, operation of other circuits like multipliers can be made quicker.

Execution can be completed in less cycle. Because, in pipelining instruction can be implemented at the same instant.