Computer Basics Tutorials

Computer Basics | Software

A computer is an electronic hardware device that processes data in binary format. Computer data is represented in bits (binary digits). A bit is the smallest unit of storage that stores a 1 or 0 (true or false). Eight bits is one byte. One byte represents a single text character, such as a letter, number, or symbol.

• a kilobyte is 1,024 bytes (2ˆ10)
• a megabyte is 1,048,576 bytes (2ˆ20) - 1024 kilobytes
• a gigabyte is 1,073,741,824 bytes (2ˆ30) - 1024 megabytes
• a terabyte is 1,099,511,627,776 bytes (2ˆ40) - 1024 gigabytes
• a petabyte is 9,007,199,254,740,990 bytes (2ˆ50) - 1024 terabytes

Different encoding types are used to represent text characters. ASCII uses eight bits to represent each text character. Unicode uses sixteen bits to represent each text character. Unicode is a universal format that represents text characters in multiple regions and languages.

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HARDWARE:

Memory...

Main memory, also known as RAM (random access memory), stores and processes data temporarily and is erased when the computer is turned off. Secondary memory stores and processes data permanently on devices such as a hard drive, CD/DVD drive, or thumb drive.



CPU (central processing unit)...

All basic computer operations are carried out by the CPU. The CPU reads instructions from RAM then executes programs one at a time, measured in cycles-per-second. One cycle is 1 hertz (Hz). The CPU retrieves, decodes, and validates sets of instructions from memory.



Buses...

The buses carry bits from one computer subsystem to another through sets of parallel wires. A bus size is measured in bits. Each wire carries one bit. There are three types of buses...

• the data bus carries data from one subsystem to another
• the address bus carries the address of the main memory location
• the control bus carries control information

I/O (input/output) devices...

The I/O devices include the keyboard, mouse, monitor, printer, scanner, CD/DVD drive, etc.

SOFTWARE:

Kernel...

The kernel is the main control program of the OS (operating system), which manages hardware and software including file, memory, and disk management.



Device drivers...

Device drivers interact with all hardware devices. A separate program manages each device.



System call interface...

The system call interface is a secure entry point to the kernel when processing files.



Language libraries...

Language libraries contain the programming languages available for creating software.



Applications...

Applications are programs available to the user.