Transcript lecture5
The Components of the system unit The Components of the system unit System Unit is a case that contains electronic components of the computer used to process data. Made of metal or plastic to protects the internal components from damage. All computers have a system unit. It is available in variety of shapes & sizes. The Components of the system unit System unit System unit System unit System unit System unit Handheld controller The Components of the system unit Processor interprets & carries out the basic instructions that operate a computer. Memory holds data waiting to be processed & instruction waiting to be executed. Processor & Memory are connected to a circuit board called the motherboard. Adapter cards are circuit boards that provide connections and functions not built into the motherboard. Devices outside the system unit often attach to the ports. A drive bay holds one or more disk drive. The Power supply provide the computer with the electricity. The Components of the system unit Motherboard , called system board. It is a main circuit board of the system unit. Many electronic components attach to the motherboard, others are built into it. Ex: adapter cards, a processor chip and a memory module. The Components of the system unit Processor, called the central processing unit (CPU), Microprocessor. Its contain a control unit & an arithmetic logic unit (ALU). These 2 components work together to perform processing operations. Processor Control Unit ALU Instructions Data Information INPUT DEVICES Data MEMORY Instructions Data Information Storage Devices information OUTPUT DEVICES The Components of the system unit The operations typically performed by a CPU are: 1. CPUs control the reading of programs and input files. 1. Its activates input unit to read program and data. 2. Controls the transmission of program & data files from disk to main memory. 2. CPUs process data according to instructions in a program. 1. Data can be processed arithmetically- number can be added, subtracted, multiplied and divided. 2. Logical tests can be performed on data. E.g., comparison. 3. Data can be transmitted or copied from one area of primary storage to another. 3. CPUs control the creation of output. The Components of the system unit The Arithmetic Logic Unit performs arithmetic, comparison and other operations. The Control Unit Handles the transmission of data into and out of the CPU and supervises its overall operations. Its interprets each instruction issued by a program & then initiates the appropriate action to carry out the instruction. The Components of the system unit Registers The CPU contain special storage areas called registers. Their function is to hold instructions, data values, memory addresses of both the instructions and data. There are 4 basic types of it: 1. Instruction register hold instruction 2. Address register hold address of( data , next instruction ). 3. Storage register store data retrieved from main memory prior to processing. 4. Accumulator store the results of arithmetic & logic operations The Components of the system unit Machine Cycle For every instruction, a processor repeats a set of four basic operations: 1. Fetching process of obtaining a program instruction or data item from memory. 2. Decoding process of translating the instruction into signals the computer can execute. 3. Executing process of carrying out the commands. 4. Storing, if necessary. Means writing the result to storage device. The Components of the system unit The System Clock Every CPU has a clock, It’s a small quartz crystal circuit , which generates regular clock pulses that control the timing of all computer operations. Processing actions occur at each “tick” of the electronic clock. The Speed of the clock determines the speed at which the CPU can process data. The Components of the system unit Clock Speed Speed is measured in megahertz (MHz) or (GHz). 1MHz is a million pulses per second. 1GHz is a billion pulses per second. The faster the clock speed, the more instruction the processor can execute per second (hertz). Clock speed measure the internal speed. The Components of the system unit Comparison of Personal computer Processors The leading processor chip manufacturers for personal computers are Intel AMD ( advanced Micro Devices) Transmeta IBM Motorola The Components of the system unit Comparison of Personal computer Processors Intel Pentium M processor used in Notebook & Tablet Computers . Xeon & Itanium processor, are ideal for workstations and servers. The Components of the system unit Comparison of Personal computer Processors AMD is the leading manufacturer of Intel-compatible processors. It less expensive than Intel processors. Transmeta is manufacturer of Intel-compatible processors, specializes in processors for mobile computers and devices. The Components of the system unit Comparison of Personal computer Processors IBM processor or Motorola processor had a different design from the Intel-style processor. Until recently, Apple computers used only an IBM processor or Motorola processor. Today’s Apple use Intel processors. The Components of the system unit How the CPU represents data Binary system based on two digits 0 and 1. 0 : off 1 : on Bit is a the smallest unit of data the computer can process. Byte a group of 8 bits. A byte can be represent characters. Characters can be a letter, digit, or symbol. The Components of the system unit How the CPU represents data The different combinations of 0s and 1s are defined by patterns called a coding schema. There are tow popular coding scheme: 1. ASCII stands for American Standard Code for Information Interchange. 2. EBCDIC stand for Extended Binary Coded Decimal Interchange Code. The Components of the system unit Memory Memory consist of electronic components that store instructions waiting to be executed by the processor, data needed by those instructions, and the results of processed data ( information). Memory usually consist of one or more chips on the motherboard or some other circuit board in the computer. The Components of the system unit Memory Stores 3 basic categories of items: 1. The operating system and other system software that control or maintain the compute and its devices 2. Application programs 3. The data being processed by the application programs and resulting information. The Components of the system unit Memory sizes It’s the number of bytes the chip or devices has available for storage. Term Abb. Approximate no. of byte Exact no. of byte Kilobyte KB or K 1000 1,024 Megabyte MB 1Million 1,048,576 Gigabyte GB 1Billion 1,073,741, 824 Terabyte TB 1 Trillion 1,099,511,627,776 The Components of the system unit Type of Memory The system unit contains tow types of memory: 1. Volatile memory Loses its contents . Temporary memory. Example, RAM. 2. Nonvolatile memory doesn't lose its content when power is removed form the computer. Permanent memory. Example, ROM, Flash memory, and CMOS. The Components of the system unit RAM ( Random Access Memory ), Also Called main memory. consists of memory chips that can be read from and written to by the processor and other devices. The content my changed. Saving is a process of copying items from RAM to a storage device such as a hard disk. The Components of the system unit RAM ( Random Access Memory ) Three basic types of RAM chips exist: DEAM Dynamic RAM Chips must be re-energized constantly or they lost their contents. SRAM Static RAM Faster and more reliable than any variation of DRAM chips. They don’t have to be re-energized as often as DRAM chips. MRAM Magnetoresistive RAM Stores data using magnetic charges instead of electrical charges. It has greater storage capacity, consumer less power, and has faster access times than RAM The Components of the system unit RAM ( Random Access Memory ) RAM chips usually reside on a memory module, which is a small circuit board. Memory slots on the motherboard hold memory modules. The Components of the system unit RAM configurations The amount of RAM necessary in a computer often depends on the types of software you plan to use. The more RAM a computer has, the faster the computer will respond. The amount of RAM in computers purchased today ranges from 256 MB to 16 GB. The Components of the system unit Cache Memory Helps speed the processes of the computer because it stores frequently used instruction and data. There are 2 types of cache: 1. L1 cache Is built directly in the processor chip. It has small capacity ranging from 8KB to 128KB. 2. L2 cache Slower than L1, has a Larger capacity ranging from 64KB to 16 MB. Advanced transfer cache, a type of L2 built directly on the processor chip. PC today typically have from 512 KB to 2 MB of Advanced transfer cache The Components of the system unit Cache Memory Cache speeds up processing time because it store frequently used instructions and data. When the processor needs an instruction or data, it searches memory in this order : L1 > L2 > RAM > hard disk or CD. The Components of the system unit ROM ( Read Only Memory) The data on most ROM chips cannot be modified. Manufacture of ROM chips often record data, instructions, or information on the chip when they manufacture the chip. Computers almost always contain a small amount of read-only memory that holds instructions for starting up the computer. The Components of the system unit PROM (programmable read-only memory): A PROM is a memory chip on which you can store a program. But once the PROM has been used, you cannot wipe it clean and use it to store something else. Like ROMs, PROMs are non-volatile. EPROM (erasable programmable read-only memory): An EPROM is a special type of PROM that can be erased by exposing it to ultraviolet light. EEPROM (electrically erasable programmable read-only memory): An EEPROM is a special type of PROM that can be erased by exposing it to an electrical charge. The Components of the system unit Flash Memory A special type of EEPROM Is a type of nonvolatile memory that can be erased electronically and rewritten. Most computers use flash memory to hold their startup instructions because it allows the computer easily to update its contents. Many modern PCs have their BIOS stored on a flash memory chip so that it can easily be updated if necessary. Such a BIOS is sometimes called a flash BIOS. The Components of the system unit CMOS ( Complementary metal-oxide semiconductor.) Some RAM chips, flash memory chip and other types of memory chips use CMOS because it provides high speeds & consumes little power. CMOS technology uses battery power to retain information even when the power to the computer is off. Personal computers also contain a small amount of battery-powered CMOS memory to hold the date, time, and system setup parameters. The Components of the system unit Memory Access Time It is the amount of time takes the processor to read data, instructions, information from memory. It’s affects how fast the computer process data. Access time on memory can be more than 200,000 times faster than accessing data on a hard disk because the mechanical motion of it. The Components of the system unit Memory Access Time Term Abb. Speed Millisecond ms One-thousandth of a second Microsecond μs One-millionth of a second Nanosecond ns One-billion of a second Picosecond ps One-trillionth of a second The Components of the system unit Expansion Slot and Adapter Cards Expansion slot is a socket on the motherboard that can hold an adapter card Adapter card sometimes called an expansion card is a circuit board that enhances functions of a component of the system unit and/or provides connections to peripherals. Peripheral is a device that connects to a system unit and is controlled by the processor. Ex: keyboard, printer. The Components of the system unit Types of adapter cards Adapter Card Graphics accelerator Modem Network Sound Video Purpose Increases the speed at which graphics are displayed Connect other computers through telephone or cable TV line Connects other computers and peripherals Connects speakers or microphone Connects a monitor The Components of the system unit Expansion Slot and Adapter Cards Sometimes all functionality is built into the adapter card. With others, a cable connects the Adapter card to device. Some motherboard include all necessary capabilities and do not require adapter cards. Other motherboard may require adapter cards to provide capabilities such as sound card & video card. The Components of the system unit Ports and Connectors Port is the point at which a peripheral attaches to or communicates with a system unit so the peripheral can send data to or receive information from the computer. the term jack sometimes is used to identify audio and video ports. Port have a different types of connectors, A connectors joins a cable to a peripheral. The Components of the system unit Serial Ports is a type of interface that connects a device to the system unit by transmitting data one bit at a time. Its for device that no need fast data transmission rate such as mouse, Keyboard or modem. COM Port ( communications port) on system unit is one type of serial port. The Components of the system unit Parallel Ports is an interface that connects a device by transferring more than one bit at a time. Can transfer eight bits of data ( one byte) simultaneously through eight separate lines in a single cable. The printers using a parallel port. The Components of the system unit USB Ports, Short for universal serial bus port. Can connect up to 127 different peripherals together with a single connector. The latest version of USB called USB 2.0. USB 2.0 is a more advanced and faster USB, with speeds 40 times higher than that of its predecessor. USB hub is a device that plugs in a USB port on the system & contains multiple USB ports. The Components of the system unit FireWire Ports Previously called an IEEE 1394 port. It is similar to a USB port in that it can connect multiple type of device that require faster data transmission speeds to a single connector, such as digital video camera, color printers, scanners, .. etc. Allow you to connect up to 63 devices together. You can use a FireWire hub to attach multiple devices to a single FireWire port. USB and FireWire are replacing all other types of port. The Components of the system unit Special-Purpose Ports These ports are not included in typical computers. MIDI Port SCSI Port IrDA Port Bluetooth Port The Components of the system unit MIDI Port, short for musical instrument digital interface. Serial port Connect the system unit to keyboard. SCSI Port A special high-speed parallel port. Allow you to attach SCSI peripherals such as disk driver and printers. The Components of the system unit IrDA refers to Infrared Data Association A standard for communication between devices (such as computers, PDAs and mobile phones) over short distances using infrared signals. For these wireless devices to transmit signals to a computer, both the computer and the device must have an IrDA port. To ensure nothing obstructs the path of the infrared light wave, you must align the IrDA port on the device with the IrDA port on the computer. The Components of the system unit Bluetooth Port ,An alternative to IrDA. It is s technology uses radio waves to transmit data between two devices. Unlike IrDA, do not have to be aligned with each other. If your computer not Bluetooth –enable you can use Bluetooth wireless port adapter or Bluetooth PC Cards. The Components of the system unit BUSES a set of electronic signal pathways that allows information and signals to travel between components inside or outside of a computer. Buses transfer bits from input devices to memory. from the processor to memory, and from memory to the processor. from memory to output devices. The Components of the system unit BUSES A computer's bus can be divided into two different types, Internal and External. The Internal Bus is part of the motherboard and connects the processor to main memory. It's also referred to as the System Bus. The External Bus allows the processor to communicate with peripherals. It is generally slower than the system bus. Another name for the External Bus, is the Expansion Bus. Buses consist of two part: Data bus and Address bus. The Components of the system unit BUSES Data bus transfers actual data. Address bus transfers information about data location on memory. The size of a bus, called the bus width, determines the number of bits the computer can transmit at one time. Bus Width is indicating how fast data is transmitted within the CPU. Every bus also has a clock speed. Most PC today use a 64-bit bus and have a bus clock speed of 400, 533 or 800 MHz. The Components of the system unit Power Supply Is a component of the system unit that supply computer with power. The Components of the system unit Question Time The Components of the system unit - Memory stores 3 basic categories of items ….&…..&….. …Helps speed the processes of the computer because it stores frequently used instruction and data. …. is a circuit board that enhances functions of component of the system unit and/or provides connections to peripherals. -…..is the point at which a peripheral attaches to or communicates with a system unit so the peripheral can send data to or receive information from the computer. - ……… is an interface that connects a device by transferring more than one bit at a time. - Buses consist of two part: ……… and ……...