COMPUTERISED ACCOUNTING Overview of Computer System Computer Components Overview of Computer System All physical parts of the computer (or everything that we can touch) is known as hardware. In general, computers are used to simplify mathematical and scientific principles. This process similar to how probabilities are used to know the odds of winning in a game of like free poker. Want to more about computers?. Software gives "intelligence" to the computer. Basically all computers, regardless of their size, have the same general design which consist of the following units: the CPU , memory, and input/output circuitry which are situated on the printed circuit board, also called the system board or motherboard (figure of a motherboard). Figure 2. This diagram describes the relationships between the components of the computer system The microprocessor is an integrated circuit that contains transistors, diodes, resistors, and other components interconnected to form the electronic circuit. The circuit is mounted in a metal or plastic package and connections are welded to external pins. The circuit can be accessed only through these pins. This design produces the following benefits: COMPUTER COMPONENTS Common Components The good news is that all computers have certain common components. What makes each one different are the specifications of the components, the amount and type of memory installed, the hard drive capacity, and the additional components installed, which you decide on, that enhance the function of the computer. Every computer must have a few essential components. Main Components
The three main components of a personal computer: The System Unit The system unit is the entire computer as a whole. This includes the case and all the hardware that is installed inside. The rest of these pages will cover what is contained in the system unit. Powerful electronic circuitry that makes up the computer is housed inside the case. The case can be opened by unscrewing the case screws and sliding off the cover. To avoid , the computer must be unplugged from the electrical outlet. Most system units consist of the computer case with a power supply, motherboard, memory (RAM), hard drive, floppy disk drive, CD-ROM drive, disk controller, input/output ports, video adapter, and sound board. The variation of the components inside the system unit is what makes one personal computer more powerful than another personal computer. Does all of the work for the computer 1. 2. 3. 4. Does all of the mathematics, mainly addition Does all the logical comparisons of values Directs the flow of data in a computer Controls the operation of the parts of the computer Today, all CPUs are microprocessors 5. A microprocessor is a complete computer on a silicon chip 6. A microprocessor does all of the functions of a computer ▪ stores data and instructions waiting to be used ▪ follows changeable instructions ▪ does input, processing, and output CPUs have three basic parts 7. The Arithmetic Logic Unit (ALU) ▪ does all of the mathematics in a computer ▪ does all of the logic comparisons of values ▪ some common logic comparison symbols ▪ = equal to ▪ <> ▪ > greater than ▪ <= less than or equal to ▪ >= greater than or equal to ▪ <> not equal 8. The Control Unit ▪ directs the flow of information into the CPU and/or memory or storage ▪ controls which instructions the CPU will do next 9. Registers ▪ ▪ Used to store data and instructions inside the processor Size of the registers can affect the speed and performance of the processor
Speed of CPUs 10.The speed of CPUs is measured in hertzs. ▪ A hertz is on cycle per second. ▪ Need to measure time to determine cycles per second ▪ All computers have a clock built into them for timing the cycles ▪ The clock is usually located in a small metal box on the motherboard. ▪ Today, many CPUs can complete over six (6) instructions per second. 11.Speeds of modern CPUs ▪ Most computers have a CPU that can do more than 400 MHz. ▪ MHz stands for megahertzs ▪ A MHz is 1,000,000 cycles per second. ▪ Computers will soon be at speeds of over a gigahertz, 1,000,000,000 Hertzs. Memory Primary memory can be used directly by the CPU 1. Consists of silicon chips, usually either VLS or VLSI technology is used to create the chips 2. Two forms of Primary Memory o Read Only Memory (ROM) o Random Access Memory (RAM) 3. Primary memory is also called primary storage The System Unit The system unit is the entire computer as a whole. This includes the case and all the hardware that is installed inside. The rest of these pages will cover what is contained in the system unit. Powerful electronic circuitry that makes up the computer is housed inside the case. The case can be opened by unscrewing the case screws and sliding off the cover. To avoid , the computer must be unplugged from the electrical outlet. Most system units consist of the computer case with a power supply, motherboard, memory (RAM), hard drive, floppy disk drive, CD-ROM drive, disk controller, input/output ports, video adapter, and sound board. The variation of the components inside the system unit is what makes one personal computer more powerful than another personal computer. Categories of Computers Personal computers Personal computers are desktop computers designed for an individual's use. They run programs designed to help individuals accomplish their work more productively. Servers
Servers are not designed to be used directly. They make programs and data available for people hooked up to a computer network, a collection of computers connected together so that they can exchange data Minicomputers Minicomputers are multi-user systems that can handle the computing needs of a smaller corporation or organization. Many people use them simultaneously by means of remote terminals or personal computers Supercomputers Supercomputers are ultra fast computers designed to process hugh amounts of scientific data then display the underlying patterns that have been discovered. Input Devices An input device lets you communicate with a computer. You can use input devices to enter information and issue commands. A keyboard, mouse, scanner, digital camera, touch pads and joystick are examples of input devices. Some Common Computer Input Devices: Keyboard • • • Used to type data into the computer Most common input device today Has special keys for giving the computer commands o Commands tell the computer to do something, like save the file o These special keys are called command or function keys Pointing Devices • • Pointing devices move some object on the screen and can do some action Common pointing devices o Mouse - most common pointing device o Track ball - basically an upside down mouse o Joystick o Game controller o Scanner o Digital Camera o Microphone o CD-ROM/DVD-ROM o Video Capture Card Output Devices An output device displays information on a screen, creates printed copies or generates sound. A monitor, printer, and speakers are examples of output devices.