Academic PowerPoint Computer System – Architecture
Computer System u A computer system consists of w HARDWARE (physical machinery) w SOFTWARE (applications, programs)
Computer A computer consists of: u Input/Output devices u CPU (Central Processing Unit)/System Unit u Memory u Secondary storage
A Computer Memory Secondary Storage Input/Output System Unit System Unit
Computer Types u Computer types range from small personal computers to large supercomputers. u In between are the categories of servers, minicomputers and mainframe computers.
Personal Computers (PCs) u Relatively small u Inexpensive u Designed for single users u Desktops, laptops, notebooks, palmtop u Becoming increasingly powerful u Very popular
Personal Computers (PCs) u Embedded w computers or processors that are placed inside other objects u cars u stereos u household appliances (video, ovens etc) u video systems
Servers u Computers that are designed to support a network. u Powerful CPU u Capable of using more than one CPU u Large memory u Large storage capacity u High speed communications
Minicomputers u Computer systems that can accommodate several users at the same time. u Large storage capacity. u Excellent processing capabilities. u Used in small business
Mainframes u Large, powerful and fast. u Can accommodate a large number of users at one time. u Requires separate room. u Used by larger companies and organisations.
Supercomputers u The most powerful and fastest. u Very expensive. u Used for complex calculations, military applications, simulations and high tech businesses.
The System Unit u This is where program instructions are executed and data is manipulated u Components w motherboard w memory w co-processors w microprocessor and CPU w buses w expansion slots w ports
Motherboard u The main board that contains the electronic components of the system unit.
Microprocessor & CPU u On a PC the CPU is contained on a single circuit called a microprocessor. u An integrated circuit is also called a chip, that is etched on a small slice of silicon.
CPU Components u Control Unit (the brain) w co-ordinates the control of data and repeats the machine cycle FETCH DECODE EXECUTE STORE
u Arithmetic Logic Unit (ALU) w performs arithmetic & logic operations u Registers w temporary storage locations for data immediately before, during and after execution by the CPU CPU Components
CPU Characteristics Speed Clock speed (an electronic impulse) affects the machine cycle Measured in megahertz (MHz) Machine Cycle The time taken is a fraction of a second MIPS (millions of instructions per second) are used to measure machine cycle time
Memory u Read Only Memory (ROM) u Random Access Memory (RAM) u Located close to the CPU u Working storage area for system and program instructions and data. u Fast access
Co-processors u A form of multiprocessing u more than one processing unit u This speeds processing by executing specific types of instructions while the CPU processes others. u Examples of co-processors include maths and graphic processors.
Buses u Buses are the physical wiring that connects other system components. u Data is transferred along these buses u The number of bits a bus line can transfer at any one time is called the bus width w 32 and 64 are common bus widths
Expansion Slots u A socket that is used to connect a circuit board to a device w sound card, network card u The socket that holds the card is connected to a bus that is connected to the CPU.
Ports u A socket that is used to connect a peripheral device (printer, scanner etc) to the system unit. Parallel Port Used when large amounts of data are sent or received. Printers, disk drives Serial Port Transmits one bit at a time Much slower than parallel Mouse, keyboard