July 31, 2010, 7:15 pm

T171 You, Your Computer and the Net

Software and Hardware

 

Programs are the software. Software can be written in numerous programming languages. A programming language is used to express the instructions which tell the computer what to do in response to a certain action. Software divided into 3 sections:

• Operating systems (OS). Communicates with the hardware. Acts as basis on which other software runs. The means by which other programs and the user interact. E.g DOS, Windows, UNIX and Macintosh.
• Languages. To write the software e.g. Smalltalk, C++, Java, JavaScript
• Applications. Enables the user to carry out various activities e.g. Word, Photoshop

Binary concept

At lowest level (machine level) a computer operates by switching on or off millions of transistors. The transistors can only be in one of two states:.

• On, which is represented by 1
• Off, which is represented by 0
• Transistors/switches are called two-state devices
• 1s and 0s are binary digits or bits.
• An 8 bit unit is called a byte - the basic unit of data representation.

Binary is the smallest number system that can store information. It simply uses 0s and 1s. The denary system (base 10) uses numbers 0 to 9. Binary numbers can represent, for example:

• denary numbers
• alphanumerical and 'exotic' characters
• images (bit-maps)
• sound

You can read more about binary representations here.

The computer can operate on the data because it has instructions from a program.

• The instructions are themselves binary representations.
• Data is the current information operated on by the computer program.
• The instructions are what the computer does with the data.

Programming languages tell the computer what to do. Assembly, an early language, operates at quite a low level in the computer, telling the computer where to move data and what to do with it. Assembly takes commands and converts them in to 1s and 0s, which the computer can interpret. Newer programming languages operate at a higher level than Assembly, and their arrival has made the task of programming simpler. Most computers use 16 or 32 bits to represent each word of information.

Hardware

The physical parts of the computer. Hardware includes components such as:

• microprocessor
• hard disk drive
• memory chip
• motherboard
• graphics card

Add-on hardware, also known as peripherals, such as:

• monitor
• modem
• printer
• keyboard

Components of a computer

Microprocessor (chip).

Before chips mainframes consisted of 3 circuit boards linked to form Central Processing Unit, CPU.

• Arithmetic and Logic Unit, ALU - This does the basic work, Maths and comparison functions.
• Control Unit - controls flow of data from the computer's memory into the ALU and other devices.
• Memory - Stores data and program instructions.

CPU sends data to and from the RAM (Random Access Memory) which consists of chips similar to CPU. RAM stores data the computer is currently using eg files and programs.

Microprocessor reads from and writes to a permanent data storage device, hard disk drive. It is connected to cables buses which carry the data.

Microprocessors combine the ALU and Control Unit on one chip. In a PC other chips control other devices eg graphics card. CPU is housed on circuit board , motherboard (also clock chip enabling synchronisation of processes). Also present on the board will be ROM (Read Only Memory) chips whose data cannot be altered only read.

Input/Output (I/O) devices

• Input - Mouse, keyboard
• Output - Monitor, printer

Data for these often passes through cards (circuit boards slotted into motherboard).

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