(25)₁₆ = 2 × 16¹ + 5 × 16⁰
= 32+5
= (37)₁₀

Open File Explorer by going to My Computer, or by pressing Windows Key + E on your keyboard. Find the file you want to rename, select it and select Rename on the ribbon (or press F2 on your keyboard). Type the new name you want the file to have and press Enter.

Multitasking is the running of multiple programs (sets of instructions) in one computer at the same time. Multitasking is used to keep all of a computer's resources at work as much of the time as possible.

Binary equivalent of -65 = 1000001
8 bit format =01000001
1's Complement = 10111110
Add 1 to LSB =+1
2's Complement of -65 = 10111111

Save	Save as
This will save the document without asking for a new name or location. It will over- write the original.	This will prompt to save the document using a dialog box. You will have the ability to change the file name and/or location. If you choose the same file name and location it will over-write the original. Your working document will be the one you just saved.

Different operating system used:
1. Single user, single Task Operating system
2. Multi user operating system
3. Multiprocessing operating system
4. Distributed Operating system

Multiprocessing is one of the features of operating system. It has two or more processors for a single running process. Each processor works on different parts of the same task or two or more different tasks.

Security Management features:
File access level security, System level security, Network level security.

GUI - Graphical User Interface - It allows the use of icons or other visual indicators to interact with electronic devices, rather than using only text via the command line. For example, all versions of Microsoft Windows utilize a GUI, whereas MS-DOS does not.

A Multi-user Operating system is a computer operating system (OS) that allows multiple users on different computers or terminals to access a single system with one OS on it.

Ultra violet rays are used to erase the contents of EPROM. EPROM retains its contents until it is exposed to ultraviolet light. The ultraviolet light clears its contents making it possible to reprogram the memory.

A program counter (PC) is a CPU register in the computer processor which has the address of the next instruction to be executed from memory. It is a digital counter needed for faster execution of tasks as well as for tracking the current execution point.

Instruction is a command which is given to the computer to perform an operation on a piece of data.

It depends on
(a) Clock speed
(b) Instruction set
(c) Word size

Primary Memory	Secondary memory
It is directly accessed by CPU.	It is not directly accessed by CPU.
The access of memory is done by making use of addresses or data buses.	Here the Memory access is done through the input and output channels.
The Primary memory is embedded with 2 types of technologies. They are RAM and ROM.	The secondary memory are stored in mass storage units like CD ROM, CD, DVD, Floppy disk storage.
Volatile in nature.	Non-Volatile in nature.
Much faster than the secondary Memory.	Slower than the Primary Memory.
Costlier than secondary memory.	Cheaper than the Primary Memory.
It is temporary memory.	Secondary memory is permanent.

Input Unit	Output Unit
An input device feeds information to a computer system for processing.	output device reproduces or displays the results of that processing.
Input devices only allow for input of data to a computer.	output devices only receive the output of data from another device.
It is a peripheral device used to provide data and control signals to an information processing system such as computer.	It is a unit which sends data from the computer to another device.
Eg. keyboard, mouse	Eg. printer, monitor

The control unit controls the flow of data between the CPU, memory I/O devices. It also controls the entire operations of a computer.

The ALU is a part of CPU where various computing functions are performed on data. ALU performs arithmetic operations such as addition, subtraction, multiplication, division and logical operations.

Computer is an Electronic Machine, capable of performing basic operations like addition, multiplication, division etc. Computer accepts data as input, process it, produce output and stores it for future.