A computer is an electronic device that accepts data (input), processes it, and generates results (output).
A computer system includes the computer itself along with additional hardware and software.
A computer system comprises a central processing unit (CPU), memory, input/output devices, and storage devices.
These components work together to deliver the desired output.
Computer systems vary in form and size, from high-end servers to personal desktops, laptops, tablets, and smartphones.
Central Processing Unit (CPU)
The CPU is the electronic circuitry that carries out processing; it's the "brain" of the computer.
It's also called a processor and is physically placed on integrated circuits (ICs) made of semiconductor materials.
The CPU receives instructions and data through programs, fetches them from memory, performs arithmetic and logical operations, and stores the result back in memory.
While processing, the CPU stores data and instructions in local memory called registers, which are limited in size and number.
Registers are used for storing data, instructions, or intermediate results.
The CPU has two main components: the Arithmetic Logic Unit (ALU) and the Control Unit (CU).
The ALU performs arithmetic and logic operations.
The CU controls sequential instruction execution, interprets instructions, and guides data flow through memory, ALU, and input/output devices.
CPU is also known as a microprocessor.
Input Devices
Input devices send control signals to a computer and convert input data into a digital form that the computer can accept.
Examples include keyboard, mouse, scanner, and touch screen.
Braille keyboards are available for visually impaired users.
Data can also be entered through voice, such as with Google voice search.
Data entered through input devices is temporarily stored in the main memory (RAM).
For permanent storage, data and instructions are stored in secondary memory.
Output Devices
Output devices receive data from a computer system for display or physical production and convert digital information into human-understandable form.
Examples include monitors, projectors, headphones, speakers, and printers.
Commonly used printers include inkjet, laserjet, and dot matrix.
3D printers build physical replicas of digital 3D designs and are used in manufacturing and medicine.
Evolution of Computer
Computing devices have evolved from simple calculators to powerful data processors in a relatively short time.
The Von Neumann architecture consists of a CPU, memory, input/output devices, and communication channels.
Electronic Numerical Integrator And Computer (ENIAC) is considered the first binary programmable computer based on Von Neumann architecture.
Large Scale Integration (LSI) in the 1970s allowed the integration of a complete CPU on a single chip, called a microprocessor.
Moore’s Law predicted exponential growth in the number of transistors on a microchip.
In the 1980s, Very Large Scale Integration (VLSI) integrated around 3 million components on a chip.
Super Large Scale Integration (SLSI) now allows fabrication of high density of transistors (approx 106 components) on a single IC.
IBM introduced its first personal computer (PC) in 1981, and Apple introduced Macintosh machines in 1984.
The popularity of PCs surged with the introduction of Graphical User Interfaces (GUI).
The growth of the World Wide Web (WWW) in the 1990s accelerated computer usage.
Laptops, smartphones, tablets, and personal digital assistants have further advanced personal computing.
The next wave includes wearable gadgets and smart appliances as part of the Internet of Things (IoT), leveraging artificial intelligence.
Timeline of Computing Technology:
Abacus: Invented almost 3000 years ago for simple arithmetic calculations.
Pascaline: Blaize Pascal's mechanical calculator for addition and subtraction (1642).
Analytical Engine: Charles Babbage's mechanical computing device for inputting, processing, storing, and displaying output (1834); which formed the basis of modern computers.
Tabulating Machine: Herman Hollerith's machine for summarizing data stored on punched cards (1890).
Turing Machine: A general-purpose programmable machine capable of solving any problem by executing programs stored on punched cards (1937).
EDVAC/ENIAC: Computers developed based on John Von Neumann's concept of stored program (1945).
Transistor: Replaced vacuum tubes, developed at Bell Labs using semiconductor materials (1947).
Integrated Circuit (IC): A silicon chip containing an entire electronic circuit in a small area (1970).
Computer Memory
A computer system needs memory to store data and instructions for processing.
Primary memory (main memory) is what we usually refer to as "memory."
Secondary memory (storage device) stores data, instructions, and results permanently for future use.
Units of Memory
A computer system uses binary numbers (0 and 1) called bits to store and process data.
Bits are grouped together to form words.
A 4-bit word is called a Nibble.
An 8-bit word (two nibbles) is called a byte.
Bytes are grouped together to make bigger units of memory.
Unit
Description
Unit
Description
KB (Kilobyte)
1 KB = 1024 Bytes
PB (Petabyte)
1 PB = 1024 TB
MB (Megabyte)
1 MB = 1024 KB
EB (Exabyte)
1 EB = 1024 PB
GB (Gigabyte)
1 GB = 1024 MB
ZB (Zettabyte)
1 ZB = 1024 EB
TB (Terabyte)
1 TB = 1024 GB
YB (Yottabyte)
1 YB = 1024 ZB
Types of Memory
Computers have two types of memory: primary and secondary.
Primary Memory
Essential component where programs and data are loaded before processing.
The CPU interacts directly with primary memory for read/write operations.
Two types: Random Access Memory (RAM) and Read Only Memory (ROM).
RAM: Volatile; retains data as long as power is supplied; used for temporary storage; main memory; faster than secondary memory.
ROM: Non-volatile; retains contents even when power is off; used for permanent storage of rarely changed contents like the boot loader.
Cache Memory
High-speed memory between the CPU and primary memory to speed up CPU operations.
Stores copies of frequently accessed primary memory locations.
When the CPU needs to access memory, it first examines the cache.
Secondary Memory
Auxiliary memory for permanently storing data or instructions for future use.
Non-volatile, larger storage capacity than primary memory.
Slower and cheaper than main memory.
Cannot be directly accessed by the CPU; contents must be brought into main memory first.
Examples: Hard Disk Drive (HDD), CD/DVD, Memory Card.
Solid-State Drives (SSD) support faster data transfer speeds.
Data Capturing, Storage, and Retrieval
Data Capturing
Gathering data from different sources in digital form.
Methods: keyboard, bar code readers, remote sensors.
Heterogeneity among data sources can complicate data capturing.
Data Storage
Storing captured data for later processing.
Data is produced at a very high rate, making data storage challenging.
Decreasing cost of digital storage devices simplifies the task.
Data servers are deployed in large organizations for vast amounts of data.
Data Retrieval
Fetching data from storage devices for processing.
Minimizing data access time is crucial for faster data processing.
Data Deletion and Recovery
A significant threat is data deletion due to device malfunction, accidental erasure, or malicious attacks.
Deleting data typically involves marking the address entry as free rather than immediate removal.
Data recovery retrieves deleted, corrupted, or lost data from secondary storage devices.
Recovery is possible if the memory space has not been overwritten.
Security concerns include unauthorized deletion or recovery of data.
Mitigation strategies: limiting access, using passwords, encrypting files, using proper tools to delete/shred data before disposal of storage devices.
Software
Software comprises the set of instructions that operate computer hardware.
It is the non-physical component of a computer system.
Software and hardware complete tasks together.
Examples: operating systems, word processing tools, video players, photo editors.
A document or image stored on a disk is a softcopy; once printed, it's a hardcopy.
Need of Software
Software makes computer hardware useful and operational.
It facilitates communication between hardware components and the end user.
Software acts as an interface between users and hardware.
Categories: System software, Programming tools, and Application software.
System Software
Provides basic functionality to operate a computer by interacting directly with hardware.
Examples: operating systems, system utilities, device drivers.
Operating System
System software that operates the computer.
Manages other application programs and provides access and security.