Memory is one of the most important components of a computer system as it stores data and instructions. Every memory chip contains thousands of memory locations. In the computer, the data is stored in the form of bits and bytes. A bit is the smallest storage unit of memory. A nibble is a collection of 4 bits. Eight bits combined together to form a single byte, and 1 byte represents a single character.

 

Memory Unit

1 nibble        =        4 bit

8 bit             =        1 Byte

1024 Byte     =        1 Kilo Byte

1024 KB        =        1 Mega Byte

1024 MB        =        1 Giga Byte

1024 GB        =        1 Trea Byte

1024 TB        =        1 Peta Byte

1024 PB        =        1 Exa Byte

1024 EB        =         1 Zetta Byte

1024 ZB        =         1 Yotta Byte

Microprocessor

A microprocessor is a Central Processing Unit (CPU) on a single chip. It is a multipurpose programmable device constructed using Metal Oxide Semiconductor (MOS) technology. A microprocessor is designed to perform arithmetic and logic operations that make use of small number holding areas called Registers. In 1971 Intel Corporation fabricated the first microprocessor- 4004. It could do only add and subtract operations and that too it could process only 4 bits at a time. But Intel 4004 powered one of the first portable electronic calculators and since then the microprocessor technology has come a long way. Today we have processors with which can process up to 128 bits at a time at the speed of billion instructions per second.    

Registers

A register is a very small amount of very fast memory that is built into the CPU (central processing unit) in order to speed up its operations by providing quick access to commonly used values. All data must be represented in a register before it can be processed. For example, if two numbers are to be multiplied, both numbers must be in registers, and the result is also placed in a register. 

Instruction Set

It is the set of instructions that the microprocessor executes at a time.

Word Length

The number of bits processed in a single instruction is called word length or word size. The word size is directly proportional to the processing power of the CPU. During the processing, the internal general purpose registers hold data. So if internal registers can hold data upto 8 bits, the word length is 8 bits. If it can process 16 bits at a time, then the internal registers can hold upto 16 bits at a time and so on. Hence a 32 bit processor is about 4 times faster than an 8 bit processor. Examples of word lengths are 16 bit, 32 bit, 64 bit. The terms 16-bit CPU, 32-bit CPU, 64-bit CPU are used very often while talking about CPUs.

Clock Speed 

The microprocessor’s speed is controlled by the System Clock. The System Clock is an electronic circuit that generates pulses which are measured in million of cycles per second (MHz). The number of pulses generated by the clock per unit of time is its Clock speed. Each microprocessor is characterized by its clock speed. Nowadays microprocessors have clock speed of several GHz. 

Classification of Microprocessors

Based on architecture microprocessor can be of two types RISC and CISC

RISC:- It stands for Reduced Instruction Set Comptuter. It is a type of microprocessor architecture that uses a small set of instructions of uniform length. These are simple but primitive instructions which execute in one clock cycle. For this reason, RISC chips are less complex and also less expensive to produce. The instructions are of uniform length which interface with about 32-36 registers. The program size in case of RISC architecture is more but more memory cycles are needed to access data. To reduce the number of memory cycles, RISC keeps the necessary data in the processor itself. The drawback of RISC design is that the computer must combine or repeat operations to complete a large program consisting of many processing operations. Since instructions are simple , RISC processors are relatively simple to design. Examples of RISC processor is SPARC, POWER PC etc.

CISC:- It stands for Complex Instruction Set Computer. A CISC chip such as Intel Pentium provides programmers with hundreds of instructions of variable sizes, and the processing circuitry includes many special purpose circuits that carry out these instructions at high speeds. These instructions interface with memory in multiple mechanisms with complex addressing modes. In this case the program
size is reduced and hence lesser number of memory cycles are required to execute the instruction. So fewer general purpose registers(8-12) are present in CISC processors. Also less number of memory cycles result in faster execution of the program.

EPIC:- It stands for Explicitly Parallel Instruction Computing. It is a computer architecture that combines the best feature of both RISC and CISC. It does not use instructions of any fixed length but rather aims at parallel processing of instructions. It uses a bundle of complex instructions that in addition to basic instruction also contain information on how to run the instruction in parallel with other instructions. This greatly increases the efficiency of an EPIC processor. IA-64 (Intel Architecture-64) is Intel’s first 64 bit processor based on EPIC.

A computer works on different characters like Alphabets, Punctuation marks, Numeric characters, and other special characters. But the computer or other devices can not understand these characters so it uses some encoding standards to represent characters. Some standards are discussed below:-

 

ASCII

ASCII stands for American Standard Code for Information Interchange and pronounced as “ask-ee”. This code is the most widely used alphanumeric code in computers. It is available in two forms 7- bit and 8-bit code. ASCII-7 can represent 128 characters. Out of 7 bits, 3 are zone bits and 4 are numeric bits. ASCII-8 can represent 256 characters. Out of 8 bits, 4 are zone bits and 4 are numeric bits. It is an extended form of ASCII-7. It represents all of the standard keyboard characters as well as control functions.

Eg: 0(41) – 0101001 , a(97) – 1100001 , 1(49) – 0110001 , A(65) – 1000001

-----------------------------------------ASCII-7------------------------------------------

!	33	)	41	1	49	?	63	^	94
“	34	*	42	2	50	@	64	_	95
#	35	+	43	9	57	A	65	`	96
$	36	,	44	:	58	B	66	a	97
%	37	-	45	;	59	Z	90	z	122
&	38	.	46	<	60	[	91	{	123
‘	39	/	47	=	61	\	92	|	124
(	40	0	48	>	62	]	93	}, ~	125 ,126

-------------------------------------------------------------------------------------------

ISCII

It stands for Indian Standard Code for Information Interchange. It was developed in 1991 to use the Indian language on computers and the Bureau of Indian Standards adopted the ISCII. It is an 8-bit code capable of encoding 256 characters. These codes are used for 10 Indian scripts Devanagari, Punjabi, Gujarati, Odia, Bengali, Asami, Telgu, Kannad, Malayalam, and Tamil. ISCII code retains all ASCII characters also.

Unicode

Unicode is a new universal coding standard adopted by all new platforms. Unicode provides a unique number for every character irrespective of the platform, program, and language. It is a character coding system designed to support the worldwide interchange, processing, and display of the written texts of diverse languages. Unicode is a 16-bit code capable of representing more than 65000 characters.

 

 Number System

Each number system has a base also called a Radix. A decimal number system is a system of base 10, binary is a system of base 2, octal is a system of base 8, and hexadecimal is a system of base 16. 

These bases are the maximum number that the numbering system allows. For Example in base 10, we can count from 0 to 9, that is,10 digits. 

Conversion between different Number Systems

Decimal To Binary

Method to convert a Decimal number into its Binary equivalent:
1. Divide the decimal number by 2.
2. Take the remainder and write it on the other side.
3. Again divide the quotient by 2.
4. Repeat the same process until the decimal number cannot be divided further.
5. Write the remainders in reverse order and you get the resultant binary number. 

Example : 

Q1: Convert the Decimal number 201 into its Binary equivalent.

201 / 2 = 100          1

100 / 2 = 50            0

50 / 2 = 25              0

25 / 2 = 12              1

12/ 2 = 6                 0

6 / 2 = 3                  0

3 / 2 = 1                  1

1 / 2 = 0                  1

Answer: (11001001)2

Fractional Decimal to Binary

The conversion of the number before the point is similar to the above method but the conversion of the number after the point is done differently. 

Example

Q. Convert Decimal number 201.47 into its binary equivalent.

The binary for 201 is simply done in the above example. So, (201)10  = (11001001)2

Let us convert (0.47)10 

 

Multiply 0.47 By 2                                                         0.94

Again multiply fraction part 0.94 by 2                             1.88

Again multiply fraction part 0.88 by 2                             1.76

Same as above 0.76 X 2                                                1.52

Same, 0.52 X 2                                                             1.04

Repeat this process until the fraction part become 0. But like above in some cases, it can be a long process so we will calculate only 5-6 digits. And write all integer values from top to bottom.

So, the Final Result is (201.47)10 = (11001001.01111)2

There are 3 types of electronic computers based on the technology being used:-

1. Analog Computers
2. Digital Computers
3. Hybrid Computers

1. Analog Computers:- Analog Computers are computing device that works on continuously changeable aspects. The analog computers give approximate results. It generally deals with physical variables such as voltage, pressure, temperature, speed, etc. The accuracy of an analog computer is less as compared to digital computers.

2. Digital Computers:- A digital computer operates on digital data such as numbers. It uses a binary number system in which there are only two digits 0 and 1. Digital computers are more accurate than analog computers. Digital computers are made for both general purpose and special purpose.

A special-purpose computer is one that is built for a specific application. General-purpose computers are used for any type of application.

3. Hybrid Computers:- A hybrid computing system is a combination of analog and digital computers. It has the speed of an analog computer and the accuracy of a digital computer. It may accept digital or analog signals but an extensive conversion of data from digital to analog and analog to digital has to be done.

Classification of  Digital Computers

Based on performance, size, cost, and capacity, digital computers are classified into four different types: Super Computers, Mainframe Computers, Mini Computers, and Micro Computers.

(1) Mainframe Computer:- Mainframe computers are capable of processing data at very high speeds- millions of instructions per second. Mainframe computer setup costs very high. These computers are large and very powerful computers with very high memory capacity. These can process huge databases such as census at an extremely fast rate. They are suitable for big organizations, banks, industries, etc.

(2) Mini Computers:- Mini Computers are smaller than mainframe computers. Mini Computers are a multi-user and time-sharing system. These are mainly used in an organization where computers installed in various departments are interconnected. Mini Computers are widely used in industries, small businesses, etc.

(3) Micro Computers:- Micro Computer is a general-purpose computer. These are also known as Personal Computers. This type of digital computer uses a microprocessor and includes both desktops and laptops. The cost of these computers can a few thousand rupees. Microcomputers are used in homes or personal business.

(4) Super Computers:- The term Super Computers is used for computers with the great operating speed and Power. Super Computers are the fastest computer in all types. These are the most expensive computers because they use the latest technology to achieve superior performances. They are used only for limited applications like weather forecasting, design of drugs, scientific research centers, and simulation of complex problems.

Softwares are mainly categorized into the following categories based on their licenses:  

Open Source Software

Open Source Software (OSS) is the software that gives the users the freedom to run/use the software for any purpose and in any manner. They can be used, modified, and even redistributed. The source code is freely available to the customer. Python, Linux, etc are examples of Open Source Software.

Proprietary Software

We pay a supplier for a copy of the software which may be supplied on physical media or downloaded from the Internet. We get permission to use the software on one or sometimes more than one machine. Examples of this type of software include Microsoft Office and Microsoft Windows.

Freeware

Freeware software is free of cost and is usually bundled up with some operating system or any other software. Examples of freeware include Microsoft Internet Explorer which comes bundled up with any Microsoft operating system. People may use it for free. The source code is not available, so no modifications can be done.

Shareware

Shareware is basically a software for the trial purposes that the user is allowed to try for free, for a specified period of time. It is usually downloaded from the internet. When the trial period ends, the software must be purchased or uninstalled.

Utility software provides certain tasks that help in proper maintenance of the computer. The job of utility programs is to keep the computer system running smoothly. Nowadays many utility softwares are part of the operating system itself. Even if there is no utility software on your computer, the computer works but with the right kind of utility software, the computer becomes more reliable. Some of the commonly use utility softwares are antivirus, Disk defragmenter, backup, compression, etc.