Computer Literacy: Hardware, Software, OS, MS Office & Number Systems (Graduate Level)

Computer literacy carries 3-6 marks in every Kerala PSC graduate-level exam. This note covers hardware architecture, software classification, operating systems, MS Office operations, and number system conversions at intermediate depth.

CPU Architecture

Component	Function	Key Detail
ALU	Arithmetic and logical operations	Addition, subtraction, AND, OR, NOT
Control Unit (CU)	Directs data flow, decodes instructions	Does not process data itself
Registers	Ultra-fast temporary storage inside CPU	Accumulator, Program Counter, Instruction Register
Cache	High-speed buffer between CPU and RAM	L1 (fastest, smallest), L2, L3
Bus	Data pathway connecting components	Address bus, Data bus, Control bus

CPU Performance Factors

Factor	Description
Clock Speed	Measured in GHz; cycles per second
Word Length	Bits processed per cycle (32-bit, 64-bit)
Number of Cores	Dual-core, Quad-core, Octa-core
Cache Size	Larger cache = fewer RAM accesses

Memory — RAM and ROM in Detail

RAM Types

Type	Full Form	Feature
SRAM	Static RAM	Faster, costlier, used in cache
DRAM	Dynamic RAM	Slower, cheaper, used as main memory
SDRAM	Synchronous DRAM	Syncs with system clock
DDR	Double Data Rate	DDR4, DDR5 are current standards

ROM Types

Type	Full Form	Feature
PROM	Programmable ROM	Written once by manufacturer
EPROM	Erasable PROM	Erased by UV light
EEPROM	Electrically Erasable PROM	Erased electrically; used in BIOS
Flash Memory	(type of EEPROM)	Used in USB drives, SSDs, memory cards

RAM vs ROM Comparison

Feature	RAM	ROM
Volatility	Volatile (data lost on power off)	Non-volatile (data retained)
Speed	Faster	Slower
Usage	Running programs, OS	Firmware, BIOS, boot instructions
Writability	Read and write	Read only (mostly)
Cost	Higher per unit	Lower per unit

Data Representation

Units of Data

Unit	Equivalent	Exact Value
Bit	Smallest unit (0 or 1)	—
Nibble	4 bits	—
Byte	8 bits	—
KB (Kilobyte)	1,024 bytes	2 to the power 10
MB (Megabyte)	1,024 KB	2 to the power 20 bytes
GB (Gigabyte)	1,024 MB	2 to the power 30 bytes
TB (Terabyte)	1,024 GB	2 to the power 40 bytes
PB (Petabyte)	1,024 TB	2 to the power 50 bytes

Character Encoding

Standard	Bits	Characters
ASCII	7 bits (128 chars)	English letters, digits, symbols
Extended ASCII	8 bits (256 chars)	Adds special characters
Unicode (UTF-8)	Variable (1-4 bytes)	All world languages including Malayalam
ISCII	8 bits	Indian scripts

Number Systems and Conversions

System	Base	Digits	Prefix
Binary	2	0, 1	0b
Octal	8	0-7	0o
Decimal	10	0-9	None
Hexadecimal	16	0-9, A(10), B(11), C(12), D(13), E(14), F(15)	0x

Common Conversions (PSC Exam Favourites)

Decimal	Binary	Octal	Hexadecimal
0	0000	0	0
5	0101	5	5
8	1000	10	8
10	1010	12	A
15	1111	17	F
16	10000	20	10
25	11001	31	19
100	1100100	144	64
255	11111111	377	FF

Conversion Method: Decimal to Binary

Divide by 2 repeatedly, record remainders bottom to top.

Example: 13 in binary

• 13 / 2 = 6 remainder 1
• 6 / 2 = 3 remainder 0
• 3 / 2 = 1 remainder 1
• 1 / 2 = 0 remainder 1
• Reading bottom to top: 1101

Binary to Octal

Group binary digits in sets of 3 (from right). Each group gives one octal digit.

Example: 110101 in octal = (110)(101) = 6 and 5 = 65

Binary to Hexadecimal

Group binary digits in sets of 4 (from right). Each group gives one hex digit.

Example: 11011010 in hex = (1101)(1010) = D and A = DA

Software Classification

System Software vs Application Software

Feature	System Software	Application Software
Purpose	Manage hardware, provide platform	Perform specific user tasks
Examples	OS, Device drivers, Compilers	Word, Excel, Photoshop, Tally
User interaction	Indirect (runs in background)	Direct (user operates it)
Necessity	Essential for computer to work	Optional, based on need

Programming Language Types

Type	Examples	Characteristic
Machine Language	Binary (0s and 1s)	Directly executed by CPU; fastest
Assembly Language	MOV, ADD, SUB	Uses mnemonics; needs assembler
High-Level Language	C, Java, Python	Human-readable; needs compiler/interpreter

Compiler vs Interpreter

Feature	Compiler	Interpreter
Translation	Entire program at once	Line by line
Speed of execution	Faster (after compilation)	Slower
Error reporting	After complete scan	Stops at first error
Examples	C, C++, Java	Python, BASIC, JavaScript

Operating Systems

OS Functions

1. Process management (multitasking)
2. Memory management (RAM allocation)
3. File management (directories, permissions)
4. Device management (drivers)
5. Security (authentication, access control)

OS Comparison Table

OS	Developer	Year	Type	Key Fact
MS-DOS	Microsoft	1981	CLI	First Microsoft OS; single-tasking
Windows	Microsoft	1985	GUI	Most used desktop OS globally
Linux	Linus Torvalds	1991	CLI/GUI	Open source; kernel-based
macOS	Apple	2001	GUI	Unix-based; for Mac hardware only
Android	Google	2008	GUI (mobile)	Based on Linux kernel; most used mobile OS
iOS	Apple	2007	GUI (mobile)	For iPhone/iPad only
Ubuntu	Canonical	2004	GUI	Popular Linux distro; used in Kerala govt
BOSS	CDAC India	2007	GUI	Bharat Operating System Solutions

File Systems

OS	File System
Windows	NTFS, FAT32, exFAT
Linux	ext4, ext3
macOS	APFS, HFS+

MS Office — Graduate-Level Detail

MS Word

Feature	Detail
Extension	.docx (.doc for older)
Mail Merge	Combines template with data source for bulk letters
Header/Footer	Insert menu; repeats on every page
Track Changes	Review tab; shows edits by different users
Styles	Predefined formatting (Heading 1, Normal, Title)

Shortcuts frequently tested:

Shortcut	Action
Ctrl + Shift + L	Bullet list
Ctrl + E	Center align
Ctrl + J	Justify
Ctrl + L	Left align
Ctrl + R	Right align
Ctrl + 1	Single spacing
Ctrl + 2	Double spacing
Ctrl + Home	Go to beginning of document
Ctrl + End	Go to end of document
F12	Save As

MS Excel

Feature	Detail
Extension	.xlsx
Total Rows	1,048,576
Total Columns	16,384 (A to XFD)
Default sheets	1 (was 3 in older versions)
Cell reference	Relative (A1), Absolute ($A$1), Mixed ($A1, A$1)

Important Functions:

Function	Purpose	Syntax
SUM	Add values	=SUM(A1:A10)
AVERAGE	Mean value	=AVERAGE(A1:A10)
COUNT	Count numeric cells	=COUNT(A1:A10)
COUNTA	Count non-empty cells	=COUNTA(A1:A10)
MAX / MIN	Highest / Lowest value	=MAX(A1:A10)
IF	Conditional	=IF(A1 is 50,“Pass”,“Fail”)
VLOOKUP	Vertical lookup	=VLOOKUP(value,range,col,FALSE)
CONCATENATE	Join text	=CONCATENATE(A1,” “,B1)
LEN	Character count	=LEN(A1)
TODAY	Current date	=TODAY()

Excel Shortcuts:

Shortcut	Action
Ctrl + ;	Insert current date
Ctrl + Shift + ;	Insert current time
F2	Edit active cell
Ctrl + `	Show formulas
Alt + =	AutoSum

MS PowerPoint

Feature	Detail
Extension	.pptx
Slide Master	Controls layout/design for all slides
Transitions	Animation between slides
Animations	Movement of objects within a slide
F5	Start slideshow from beginning
Shift + F5	Start from current slide
Ctrl + M	New slide
B key during slideshow	Black screen
Esc	End slideshow

Generations of Computers — Expanded

Gen	Period	Technology	Speed	Language	Storage
1st	1940-1956	Vacuum tubes	Slow	Machine language	Magnetic drum
2nd	1956-1963	Transistors	Faster	Assembly language	Magnetic core
3rd	1964-1971	IC (SSI, MSI)	Fast	High-level (FORTRAN, COBOL)	Magnetic disk
4th	1971-present	Microprocessor (VLSI)	Very fast	C, C++, Java	Semiconductor
5th	Present-future	AI, Parallel processing	Ultra fast	Python, Prolog	Optical, SSD

Key machines by generation:

Generation	Notable Computers
1st	ENIAC (1946), UNIVAC (1951), EDVAC
2nd	IBM 1401, IBM 7094, CDC 1604
3rd	IBM 360, PDP-8
4th	IBM PC (1981), Apple Macintosh (1984)
5th	Watson (IBM), modern AI systems

File Management

Concept	Description
File	Named collection of related data stored on disk
Folder/Directory	Container for files and subfolders
Path	Location address (e.g., C:\Users\Documents\file.docx)
Extension	Suffix indicating file type (.docx, .pdf, .jpg)
Wildcard	* (any characters), ? (single character)
Root Directory	Top-level directory (C:\ in Windows, / in Linux)

File Operations

Operation	Windows Shortcut
Copy	Ctrl + C
Paste	Ctrl + V
Cut (Move)	Ctrl + X
Delete	Delete key (to Recycle Bin)
Permanent Delete	Shift + Delete
Rename	F2
Select All	Ctrl + A
New Folder	Ctrl + Shift + N
Properties	Alt + Enter

Quick Revision — 25 Graduate-Level Computer Questions

1. Cache memory is placed between: CPU and RAM
2. SRAM is used for: Cache memory
3. DRAM is used for: Main memory (RAM)
4. EEPROM is used in: BIOS, Flash drives
5. DDR stands for: Double Data Rate
6. 64-bit processor means: Processes 64 bits per cycle
7. Binary of 255: 11111111
8. Hexadecimal of 255: FF
9. Octal of 8: 10
10. 1 nibble = 4 bits
11. Unicode supports: All world languages
12. ASCII uses: 7 bits (128 characters)
13. Compiler translates: Entire program at once
14. Interpreter translates: Line by line
15. Linux file system: ext4
16. Windows file system: NTFS
17. Excel total rows: 1,048,576
18. Excel absolute reference: $A$1 (dollar sign locks)
19. F12 in Word: Save As
20. Ctrl + ; in Excel: Insert current date
21. VLOOKUP searches: Vertically (by column)
22. Mail Merge is in: MS Word
23. BOSS OS developed by: CDAC (India)
24. First IBM PC released: 1981
25. Machine language uses: Binary (0 and 1)

Compiled from Kerala PSC graduate-level computer literacy questions (2018-2025). Covers Assistant Grade, Secretariat Assistant, and University Assistant exam patterns.