Computer Knowledge for JKSSB Exams: Every Topic With Shortcuts, Formulas and Solved Examples

The computer section in JKSSB papers is short, factual and highly scoring. It appears in the Junior Assistant, Constable, Sub-Inspector and many other posts, usually as 10 to 30 marks. A few focused sessions can turn this section from guesswork into near-full marks. This guide covers each topic with the facts that recur.

1. Basic terminology and the computer cycle

A computer takes input, processes it, stores it and gives output. The CPU (Central Processing Unit) is the brain of the computer, and it has the Arithmetic Logic Unit, the Control Unit and registers. The speed of a CPU is measured in hertz, such as GHz.

2. Hardware

• Input devices: keyboard, mouse, scanner, microphone, webcam, touch screen, barcode reader
• Output devices: monitor, printer, speaker, projector, plotter
• Storage devices: hard disk drive, solid state drive, pen drive, CD, DVD, memory card
• Memory: RAM is volatile and loses its data when the power is off. ROM is non-volatile. Cache memory is a small, very fast memory between the CPU and RAM

Memory units: 8 bits make 1 byte. 1 kilobyte is 1,024 bytes, 1 megabyte is 1,024 kilobytes, 1 gigabyte is 1,024 megabytes and 1 terabyte is 1,024 gigabytes.

3. Software

System software runs the computer, such as an operating system. Application software helps the user do a task, such as a word processor. Utility software maintains the system, such as an antivirus or a disk cleaner. Firmware is software stored permanently on hardware, such as the BIOS. Open-source software has publicly available code, and Linux is a common example.

4. Operating systems

An operating system manages the hardware, memory, files and programs. Windows, Linux, macOS, Android and iOS are examples. A GUI (graphical user interface) uses windows, icons and menus. A file is stored in a folder, and a path shows where it lives, such as C:\Documents\Report.docx.

5. MS Word

• Shortcuts: Ctrl + C copy, Ctrl + X cut, Ctrl + V paste, Ctrl + Z undo, Ctrl + Y redo, Ctrl + S save, Ctrl + P print, Ctrl + A select all, Ctrl + B bold, Ctrl + I italic, Ctrl + U underline, Ctrl + F find
• File extension: .docx for a Word document
• Features: header and footer, page numbers, mail merge, spell check, tables, styles and templates

6. MS Excel

A spreadsheet is made of rows and columns, and each box is a cell with a reference like A1. A formula begins with the equals sign. Common functions are SUM, AVERAGE, MAX, MIN, COUNT, IF and VLOOKUP. A relative reference such as A1 changes when copied, and an absolute reference such as $A$1 does not.

Example: If cells A1 to A5 hold 10, 20, 30, 40 and 50, =SUM(A1:A5) gives 150, and =AVERAGE(A1:A5) gives 30.

7. MS PowerPoint

A presentation is made of slides, with transitions between slides and animations for objects on a slide. The file extension is .pptx. F5 starts the slide show from the beginning.

8. The internet and email

• Terms: a URL is the address of a web page, HTTP and HTTPS are the protocols used to transfer pages (HTTPS is secure), a browser such as Chrome or Firefox displays pages, and a search engine such as Google finds pages
• Email: To is the main recipient, Cc sends a visible copy, and Bcc sends a hidden copy. An email address has the form name@domain
• Networks: a LAN covers a small area such as an office, a WAN covers a large area, and the internet is a network of networks. An IP address identifies a device on a network

9. Security

• Virus: a program that attaches to files and spreads when they are opened. Worm: spreads by itself across networks. Trojan: hides inside a useful-looking program. Malware is the general name for harmful software
• Antivirus: detects and removes malware, and it must be updated regularly
• Firewall: filters network traffic to block unauthorised access
• Phishing: a fraudulent message that tricks you into giving passwords or bank details
• Good habits: use strong passwords, do not share OTPs, enable two-step verification and install updates

10. Number systems

Computers use the binary system, with digits 0 and 1. To convert binary to decimal, add the place values: 1011 in binary is 8 + 0 + 2 + 1 = 11. To convert decimal to binary, divide by 2 repeatedly and read the remainders from the bottom: 25 gives 1, 0, 0, 1, 1 from the top, so 25 is 11001.

How to prepare

• Spend 20 minutes a day for a week on one block each day: hardware, software, Word, Excel, the internet, security and number systems
• Write the shortcuts and formulas on one page and revise it daily
• Solve 20 questions each evening and review the answers
• Learn the full forms: CPU, RAM, ROM, URL, HTTP, LAN, WAN, USB, BIOS

Practise with the Junior Assistant computer questions, the Panchayat Account Assistant computer applications MCQs and the topic sets.