Basics of Computers and Applications
This section checks computer literacy: hardware and software, operating-system functions, number systems, MS Office, internet services, databases, networking basics and cyber safety. RRB JE questions tend to be definitional plus small conversion or spreadsheet tasks.
Core rules and concepts
- Hardware: CPU has ALU, control unit and registers. RAM is volatile; ROM is non-volatile. Input devices include keyboard, mouse and scanner; output devices include monitor and printer.
- Software: system software includes the OS and utilities; application software includes Word, Excel and browsers. An OS manages memory, files, processes and devices.
- Number systems: binary is base 2, octal base 8, decimal base 10 and hexadecimal base 16. Convert by repeated division for decimal-to-binary and by place values for binary-to-decimal.
- MS Office: relative references change on copy; absolute references use $. Common extensions: .docx, .xlsx, .pptx.
- Internet and security: HTTP/HTTPS, URL, IP address, phishing, malware and firewalls. HTTPS adds encryption; it does not guarantee a trustworthy site by itself.
Worked example
Convert decimal 45 to binary by repeated division: 45÷2 = 22 remainder 1; 22÷2 = 11 remainder 0; 11÷2 = 5 remainder 1; 5÷2 = 2 remainder 1; 2÷2 = 1 remainder 0; 1÷2 = 0 remainder 1. Read remainders upward: 101101₂.
Traps
Treating 1 KB as exactly 1000 bytes in binary contexts, calling ROM volatile, copying a formula without checking relative references, and confusing HTTP with HTTPS.