2 The Components of the System Unit.pdf

Computer The main purpose of a computer is to process data into information. CSC 16...

Computer The main purpose of a computer is to process data into information. CSC 1600 Introduction to Computer with Lab Data is a collection of unprocessed items, which can include text, numbers, images, audio and video. The Components of the Information conveys meaning and is useful to people. System Unit Components Computer consist of collection of hardware (electric, electronic and mechanical component) Hardware can be classified as: System unit Output device – system unit – input and output devices – storage devices Output device – communication devices Input device Input device System unit Motherboard Desktop Motherboard or system Flat panel Display (Output computer(System unit) slot for memory device) board, is the main circuit slot for module On desktop personal computer board of the system unit. processor chip electronic components and storage Speaker Processor and memory other expansion slots devices are part of system unit. (Output device) components are attached to for adapter cards Other devices like keyboard, mouse, the motherboard. monitor, printer, USB, scanner are outside the system unit. motherboard Keyboard Mouse (Input device) (Input device) Computer chip Computer chips are small pieces of semiconductor material (silicon) on which integrated circuits are etched. Each integrated circuit (IC) contains resistors, capacitors and transistors connected by microscopic pathways. Processor Processor Processor interprets and carries out the basic instructions that operate a Processor computer. Arithmetic Processor, is also called central processing unit (CPU) or microprocessor. Control Unit Logic Unit (ALU) In a PC, all functions of the processor usually are on a single chip. instructions, Processor core (or simply called core) contains necessary circuit to execute data, instructions. information Multi-core processors has two or more separate processor cores, where dual Input devices data memory information Output devices core and quad core are most common. instructions, data, information Storage devices Processor components Control unit A processor contains a control unit and an arithmetic logical unit. Control unit (CU) is the processor components that directs and coordinates When user runs an application, its instruction transferred from storage to most of the operations in the computer. memory. It interprets each instruction from program and then initiates appropriate Data needed by the applications enters memory from either an input device action to carry out the instruction. or a storage device. Control unit directs arithmetic and logic unit, registers and buses. Control unit interprets and executes instruction in memory and the arithmetic logic unit performs calculations on the data in memory. Resulting information is stored in memory, from which it can be sent to an output device or a storage device for future access, as needed. Arithmetic logic unit Arithmetic logic unit (ALU), is another component of processor that performs arithmetic, comparison and other operations. Arithmetic operations are basic calculation such as addition, subtraction, multiplication and division. Comparison operations involves, comparison two data and finding out whether its greater than, less than, equal to or not equal to. Register System clock Register is a small high speed storage inside a processor, used to hold data System clock is small quartz crystal circuit to control timing of all computer and instructions temporarily. operations. Processor have many types of registers, each with specific storage functions It generates regular electronic pulses, or ticks that sets the pace of such as: components of the system unit. – storing location from where instruction is fetched Each tick equates to a clock cycle. – storing instruction to be decoded by control unit The pace of the system clock is called clock speed measured as ticks per – storing data while ALU calculates second – storing the result of the calculation – Example, 1 GHz (gigahertz) is one billion ticks per second. The faster the clock speed, the more instruction it can execute. Performance Processor cooling Computer performance is influenced by following factors: Processor chips can generate heat, that comes with its own cooling fan, heat – clock speed sink. – processor chip type Overheated processor can cause the chips to malfunction or fail. – amount of cache Fan usually on top of processor and heat sink. – memory access time Heat sink is small ceramic or metal component with fins to attached to – bus width processor’s surface to disperse heat. – bus clock speed Other methods are liquid cooling technology and cooling pad heat sink fan processor chip Data representation Bits and Bytes Computers are digital thus it can only recognize the “ON” state and “OFF” Binary system is a number system that has only two unique state 0 and 1. state. They are called bit (binary digit), the smallest digit the computer can The state is represented using 1 and 0, where process. – 1 for electronic state of on A group of 8 bits is called a byte. – 0 for electronic state of off It provides 256 different combination of 0 and 1. Each byte represent a character, that include number, uppercase, lowercase Binary Digit Electronic Electronic state charge letters, punctuation and other alphabets.. OFF 0 I ON Coding Scheme ASCII, American Standard Code for Information Interchange is a coding scheme to represent data. Coding scheme is the combination of 0s and 1s that represents characters are defined by pattern. For example, – number 4 is represented as 00110100 – capital letter A is represented as 01000001 Coding scheme enable humans to interact with a digital computer that processes only bits. Memory Bytes and Addressable memory Memory size Basic storage unit in memory is byte (character). Memory size is expressed in terms of number of bytes the chip has available Instruction and data loaded into memory exists as bytes. for storage. Each byte resides in temporary location that has an address. A kilobyte (KB or K) is equal to exactly 1024 byte. Address is unique number that identifies location of byte in memory. – computer users usually round a kilobyte down to 1000 byte. Example, 100 KB can hold approximately 100,000 bytes (characters). Data or instruction in memory is accessed using the address. Other common sizes are: – Megabyte (MB) approximately 1 million bytes – gigabyte (GB) approximately 1 billion bytes – terabyte(TB) approximately 1 trillion bytes Types of memory RAM Computers and mobile devices contain 2 types of memory volatile and non RAM (Random Access Memory) or main memory. volatile. Memory chip that can read from and written to by the processor and other volatile memory loses its content when power is turned off. devices. – RAM is the most commonly type of volatile memory. Operating system files loaded into memory when the computer is turned on. non-volatile memory retains its content even after power is removed These file remain in memory as long as the power in ON. – ROM, flash memory, and CMOS is nonvolatile memory. Application and data loaded as needed. RAM is volatile, to keep the data, it have to be saved to storage device like hard drive. RAM types Memory module RAM types are dynamic RAM (DRAM) and Static RAM (SRAM) Memory module is a circuit board containing the RAM chip, connected to Dynamic RAM (DRAM) chip need to be re-energized constantly otherwise motherboard using memory slot. their content will be lost. SIMM Single inline memory module – Other DRAM variations: SDRAM, DDR SDRAM, DDR2, DDR3, DDR4 and DIMM Dual inline memory module. RDRAM. Static RAM chip do have to re-energized as often as DRAM. – The chip is faster and more reliable but more expensive. – Example of SRAM is cache. memory memory chip module Magnetoresistive RAM (MRAM) data is stored using magnetic charge. – > storage capacity, use less power, faster access time. Cache ROM Cache (cash) is a temporary storage area, to improve computers Read Only Memory (ROM rahm) is a memory chip storing permanent processing time. data and instructions. Two types of cache are memory cache and disk cache. Only can be read data on ROM, the data cannot be modified. help speed the process by keeping frequently used instruction and data. non-volatile, retains stored data when power is off. Memory cache type are: Level1 (L1) and Level2 (L2) computer, mobile and peripherals like printer Some may even have Level 3 (L3) Firmware contains data, instruction for computer or mobile’s start-up instructions. Type or ROM – Programmable read-only memory (PROM) like firmware – Erasable programmable read-only memory (EPROM) microcontrollers – Electrical erasable programmable read-only memory (EEPROM) microcontroller and flash memory Flash Memory CMOS Flash memory is nonvolatile memory that can be erased electronically and CMOS (SEE-moss) Complementary metal-oxide semiconductor. rewritten. Used in computer, smartphones and digital cameras. Computer uses flash to hold start up instruction as its is easier to update. provides high speed and consumes little power. Build from EEPROM. Used in RAM chip and flash memory chip Mobile devices and peripherals devices use flash memory chip to hold data Uses battery power to retain information, even when power is OFF. and program. In computer, CMOS is a small battery powered chip that stores critical system information such as data, time and hardware configurations. Keeps BIOS (Basic input/output system) settings that tells computer how to interact with it hardware. Memory access time Memory access time is the amount of time it takes the processor to read data, instructions and information from memory. accessing data in memory is faster than accessing data from hard disk. A nanosecond is one billion of a second Another, MHz for example, 800 MHz Expansion Slots and Adapter Cards Expansion Slots and Adapter Cards Removable flash memory Expansion slot is a socket on the motherboard that is used to hold an adapter Removable flash memory includes: card. – Memory card Adapter card, also called expansion card, is a circuit board that enhances – USB flash drives – PC cards/expressCard modules function of a component of the system unit. – Sound card, video card, graphics card, etc Memory card is a removable flash memory device. It also provides connection to peripherals. This device is inserted and removes from a slot in a personal computer, – peripherals is a devices that connects to the system unit, and is controlled by the mobile devices or game console and some printers. processor in the computer. A USB flash drive is a flash memory storage device that plugs in a USB port – example, modem, disk drives, printers, scanners and keyboard. on a computer or mobile device. Removable flash memory A desktop, notebooks tablets have a PC card slot or ExpressCard slot. PC card is a thin, credit card-sized removable flash memory device. Used to enable a notebook and tablet to access internet wirelessly. ExpressCard module, can be used as removable flash memory device. to add memory, communication, multimedia and security capabilities. Ports and Connectors Ports and Connectors Desktop Port is the point at which a peripheral attaches to or communicates with a system unit so that the peripheral can send data to or receive information from the computer. External devices like keyboard, printer, mouse, microphone attached by cable to a port on the system unit. Connector joins a cable to a port. One end of cable to system unit and another end to the port on peripheral. Commonly used ports – USB (Universal Serial Bus) – Fire-wire – Others: Bluetooth, SCSI, eSATA, IrDA, MIDI Laptop USB Port USB (Universal Serial Bus) used to connect multiple different peripherals with a single connector. Deices that connect to USB port such as mouse, printers, digital camera, scanner, etc. USB Varieties: – Type A – Type B – Mini-B USB FireWire USB 2.0 (High Speed USB) is more advanced and faster. FireWire port known as IEEE 1394 is similar to USB USB 3.0 faster than USB 2.0. Connects to multiple types of devices that requires faster data transmission USB is backward compatible, means a USB supports older USB devices speed. USB Hub is used to attach multiple peripherals. Used on video camera, digital VCRs, color printers, scanners, digital camera and DVD players. Version, FireWire 400, FireWire 800, FireWire 1600, and FireWire3200. FireWire hub attach multiple devices to single FireWire port. Ports and connectors Port replicator, is an external device that provides connections to peripherals through ports built into the device. Docking station is a stationary work place where laptop or other mobile devices to connects with peripherals devices and monitors to expand its capability. Buses Buses Bus Width Bus is an electrical channels that allow various devices both inside and The width refers to size of bus, determines number of bits that computer can attached to the system unit to communicate with each other. transmit at one time. Buses are used to transfer bits from Example, 64 bit bus can transmit 64 bit (8 bytes) at a time. – input devices to memory, The larger the number of bits a bus handles, the faster a computer can – memory to the processor transfer data. – the processor to memory can transfer in fewer number of steps. – memory to output or storage devices. Buses consist of two parts: a data bus and an address bus. The data bus is used to transfer actual data and the address bus is used to transfer information about where the data should reside in memory. Word size Types of buses Word size, is the number of bits the processor can interpret and execute at a Computer has given time. – system bus - also called front side bus (FSB), is part of the motherboard and – 64 bit processor can manipulate 64 bits at time. connects the processor to main memory. The larger the word size the computer can process more data at same time. – backside bus - BSB connects the processors to cache. In most computer, word size is the same as the bus width. – expansion bus - allows the processor to communicate with peripherals devices. When some mention about bus they normally refers to system bus. Bay A bay is an opening inside the system unit in which you can install additional equipment. A bay is different from a slot on the motherboard A drive bay is a rectangular opening that typically holds disk drives. Other bays house card readers and widely Bay and Power supply used ports such as USB, Fire-wire, and audio ports. Power supply The power supply is the component of Mobile computer and devices runs using power supply or batteries. the system unit that converts the wall Rechargeable lithium ion batteries outlet AC power into DC power. Most batteries are removable. standard wall outlets, which supply an ultra-thins laptop has no removable batteries. alternating current (AC) of 115 to 120 volts. computer requires a direct current (DC) ranging from 5 to more than 15 volts. Power supply comes with a fan that helps it to cool down.