计算机文化基础双语课件-Chapter2-computer-hardware.ppt

1、 Hardware System System unit CPU(program control unit+Arithmetic Logic unit)Memory&Storage(External Memory)Input Output 2.1:An Overview 2.2:Microprocessors 2.3:Memory 2.4:Storage Devices 2.5:Input and Output DevicesKM chart of Chapter TwoWhats a personal computer system?What are the components of a

2、typical PC?System Unit Keyboard Mouse Hard disk drive CD and DVD drivers Other storage Sound system Display system:graphics card monitor Network and Internet access printer Information processing cycleWhat is a microprocessor?is an integrated circuit designed to process instructions P27 of E Whats a

3、 computer chip?the terms computer chip,microchip,and chip originated as technical jargon for integrated circuit.integrated circuit is an super-thin slice of semiconducting material packed with microscopic circuit elements,such as wires,transistors,capacitors,logic gates,and resistors.(p28)Motherboar

4、d(circuit board)many chips are housed on motherboard.processor chip;computer memory;system bus;CPUs functions1)Executes instructions to process data,for example,perform arithmetic,sort list,format document.2)Retrieves instructions and data from RAM,after processing instructions,places the results ba

5、ck into RAM.CPURAMInstructionsDataPrograms and instruction sets:How do digital devices process data?The data is manipulated under the control of a computer program.The human-readable version of a program is called source code.How does source code get converted?The procedure for translating source co

6、de into 0s and 1s can be accomplished by a compiler or an interpreter.A compiler converts all the statements in a program in a single batch,and the resulting collection of instructions,called object code,is placed in a new file.(p30 f1-34)“语言”是人机交流的工具 程序是用“语言”写成的计算机可以识别的“文章”用于编写计算机可以执行的程序的语言称为程序设计语言

7、机器语言机器语言机器指令机器指令0 0 或或 1 1 代码代码 与语言习惯差别很大难以学与语言习惯差别很大难以学习和记忆依赖机器的类型习和记忆依赖机器的类型汇编语言汇编语言用助记符代替机器代用助记符代替机器代码；用变量代替各类码；用变量代替各类地址地址克服记忆的难点其他与假期克服记忆的难点其他与假期语言类似语言类似高级语言高级语言类似数学语言、接近自然语言、具有通用性和可移植类似数学语言、接近自然语言、具有通用性和可移植性、不依赖具体的计算机类型性、不依赖具体的计算机类型可执行程序可执行程序编译程序编译程序高级语言程序高级语言程序目标程序目标程序连接程序连接程序编译编译连接连接Compiler

8、 An interpreter converts and executes one statement at a time while the program is running.执行执行解释程序解释程序高级语言程序高级语言程序解释解释Interpreter What does the conversion process produce?Instruction set:collection of preprogrammed activitiesis designed to be general purpose so that programmers can use it in creati

9、ve ways for the wide variety of tasks performed by all kinds of digital devices.Instruction:each instruction has a corresponding sequence of 0s and 1s.E.g add-00000100 Machine language:can be directly executed by the processors circuitry A machine code instruction has two parts:the op code and the o

10、perand.Eg:instruction:add 1 00000100 00000001Op codeOperandP31 f1-36 指令：计算机能够识别并执行的“操作命令”指令一般由操作码和操作数组成操作码操作码 目标操作数目标操作数 源操作数源操作数操作码操作码 操作数操作数表示功能（操作）表示功能（操作）表示操作的对象表示操作的对象Program ControlCentral Processing UnitArithmetic LogicUnit(ALU)Main memory I/OEquip-mentregisterProcessor logic What happens whe

11、n a computer executes an instruction?(p30)1.Fetch instruction 4.Increment pointer to the next instruction3.Execute instruction2.Interpret instructionCPU ArchitectureALUControl unitA CPU have two main partsALU performs:arithmetic operations addition,subtraction,multiplication,division;logical operati

12、ons AND,OR,Exclusive-OR,NOT.Program control unit（程序控制单元）（程序控制单元）-Control the operation of CPU;Arithmetic and logic unit(ALU)（运算器）（运算器）-Perform data processing;Registers (寄存器组）寄存器组）-Internal storage;CPU interconnection（CPU内部总线）内部总线）-Provides communication among them.The Control Units function(p.32)-R

13、etrieves an instruction from RAM and puts it in the instruction register.-The RAM address of the instruction is kept in the instruction pointer.-When the instruction has been executed,the address in the instruction pointer changes to the RAM address of the next instruction to be executed.Control Uni

14、tInstruction pointer Instruction RegisterM1ADD two numberRAMAddress M1Address M2Address M3M2MUL two numberCPU Performance Factors-Moore law-“A chain is only as strong as its weakest link”.A high-performance processor with a slow hard disk,no disk cache,and a small amount of RAM is likely to be slow

15、at tasks such as starting programs,loading large amount of data,printing and scrolling through long document.-CPU speed is influenced by clock speed,bus speed,word size,cache size,instruction set,number of cores,and processing techniques.Specifications for these factors allow you to compare differen

16、t CPUs.CPU Performance FactorsMicroprocessor Clock microprocessor clock-a timing device that sets the pace for executing instructionsMegahertz(MHz)-a million cycles per secondGigahertz(GHz)-a billion cycles per second-Instruction cycle(the time to complete an instruction cycle)is measured in megaher

17、tz(million of cycles per second or MIPS)(CPU 的主频）;-If all other specifications are identical,higher MHz ratings faster processing-The original IBMPC is 4.77MHz,todays exceed GHz.refers to the circuitry that transports data to and from the microprocessor.A fast front side bus moves data quickly and a

18、llows the processor to work at full capacity.200MHz1250MHzWord Size（字长）（字长）The number of bits that the CPU can manipulate at one time.-Word size is based on the size of the register in CPU and the number of data line in the bus;For example,a CPU with a 8-bit word size is referred to as an 8-bit proc

19、essor.-Larger word size process more data in each instruction cycle increased performance-The first microcomputers contained 8-bit microprocessor,but todays computers contain 32-bit or 64-bit microprocessor.Cache (高速缓存高速缓存)Sometimes called“RAM cache”or “cache memory”;-It is special high speed memory

20、 that speeds access to data from RAM.-As you begin a task,the computer loads the possible data into the cache area.The CPU first checks to see if the required data is in the cache;-If all other factors are same,cache means faster processing.Instruction Set (P.31)-Instruction set is the complete coll

21、ection of instructions which are used by a particular type of central processor.-Two of the main approaches to the design of microprocessors are the Complex Instruction Set Computer(CISC)and the Reduced Instruction Set Computer(RISC).More cores usually produce faster performance multiple cores can r

22、un multiple instructions at the same time Pipelining processing-Computers with a single processor execute instructions“serially”,that is,one instruction at a time.Instruction cycle fetch-decode-execute-output-Pipelining technology:the processor can began executing an instruction before it completes

23、the previous instruction;-Pipelining speeds up processing.ControlUnitRegisters(Instruction2)Accumulator(Instruction1)RAMInstruction1Instruction2Instruction3The controlUnit decodesInstruction3The data for Instuction2 moves into a registerInstruction1 is completed1234 Parallel Processing-A computer ha

24、s more than one processor and can execute multiple instructions at the same time;This is called parallel processing;-A computer that is capable of parallel processing is called a parallel computer or“Non-von Neumann machine”;-It is the simultaneous use of several processors to perform a single job.A

25、 job may be split into tasks each of which may be processed by any available processor.Processor1Processor2Processor3ControlUnit(4)Data (1)Instruction(2)(3)Result1)Instructions are queued and waiting to enter the CPU.2)The control unit sends an instruction to the next available processor.3)Each proc

26、essors completes its assigned instruction.Because the processors finish at different times,the results might not be in sequence.4)The result are places in the correct order out of the CPU.Data bus:electronic pathway or circuit on which data travel from one location to another within the computerAddr

27、ess bus:Control bus:4 major types of memory:random access memory(RAM)read-only memory(ROM)EEPROM cache memory virtual memory1)random access memory(RAM)Capacitors hold electronic signal for data RAM Address most RAM is volatile(易失性)1)random access memory Capacity Measured in megabyte 256M-2G Speed to

28、day 8 nanoseconds(one billionth of second)(毫微秒）毫微秒）.Configuration（构造）（构造）RAM is typically configured as small circuit boards called DIMMs(dual in-line memory modules).2)Read-only Memory（ROM）-The instructions in ROM are permanent;-ROM contains a small set of instructions called the ROM BIOS(basic inp

29、ut/output system),tell the computer how to access the disk drives and other peripheral devices;-When the computer is just turned on,RAM is empty,the CPU executes the instructions in ROM BIOS that search the disk drive for the main operating system files,then load the files into RAM so that they can

30、be used during the reminder of the computing session;-Software in ROM is fixed during manufacture,but there are other ways of putting programs and data into ROM;-Including PROM,EPROM,etc.PROM(Programmable Read-only Memory)is a type of ROM which is manufactured as an empty storage array and is later

31、permanently programmed by the user.EPROM(Erasable PROM)is a type of PROM whose data can be erased by a special process so new data can be written as if it were a new PROM.EEPROM(Electrically Erasable PROM)-no power to hold data -replace CMOS technology(require a small battery)cache is a used by the

32、central processing unit(CPU)to reduce the average time to access memory smaller,faster first check in the cache When the processor needs to read from or write to a location in main memory4)Virtual Memory（虚拟内存）（虚拟内存）-A computers ability to use disk storage to simulate RAM is called virtual memory;-Al

33、lows computers without sufficient amounts of real memory to run large programs,data files;-Not as fast as RAM.Disk access time is 10 milliseconds;-Data becomes inaccessible if power fails,because the instructions that direct the computer to the location of virtual memory are stored in RAM.How comput

34、ers store mass data?1.Study storage technology:electronic,magnetic,optical -data storage life span2.Use popular software utilities to locate,organize,change,search the data 1)Storage basicsphysical storage -storage medium(media)logical storage -files,folders the data for a single file can be scatter

35、ed all over the surface of storage medium storage terminology 1)storage medium:substance that contains data 2)storage device:mechanical apparatus that record and retrieve data from storage medium.3)read,load,open write,save magnetic storage (hard disk,floppy disk,tape storage)(P36 of E.)mechanism:st

36、ore data by magnetizing microscopic particles on a disk or tape surface.flexibility for editing data and reusing areas of storage medium.data maintenance:1)place magnetic medium in a clean environment.2)recopy the data every 2 years.Why are hard disk drives so popular?1)lots of storage capacity 2)fa

37、st access to files 3)economical Hard Disk Storage A hard disk platter is a flat,rigid disk made of aluminum or glass and coated with a magnetic oxide.A hard disk is one or more platter and their associated read-write heads,typically 3 inches in diameter.Several hundreds GB capacity(40 500GB);Random

38、access;Continually in motion,so faster access to file than floppy(6 to 11 ms).cylinderFloppy Disk Storage p.68-3 inch,5 inch,zip disk;-Disk may have data stored on one side or on both sides(DSD).-3 high density 1.44MB;-Takes about 0.5s(3 inch)to spin it to maximum speed and then find a specific sect

39、or that contains data;-A zip drive(100MB)is about 20 times faster;-Random access;-Newer technologies are decreasing the use of floppy disks,using CD-ROM or DVD-ROM instead.CD(compact disc)technology was originally designed to hold 74 minutes of recorded musicDVD(digital video disc or digital versati

40、le disk)is a variation of CD technology,4.7Goptical storage (CD and DVD)(P69 of E.)stores data as microscopic light and dark spots on the disk surface1)pits(凹)and lands(凸)of medium is interpreted as 1s and 0s.Dark spots -pits -1 optical technology (CD and DVD)2)use a low-power laser beam to read dat

41、a 3)less susceptible than magnetic storage 易受影响易受影响2.4:Storage Devices storage deviceThe criteria（标准）（标准）for comparing storage devices:Versatility(多面性）多面性）-Devices can access data from several different media.Durability（耐用性）（耐用性）-More durable technologies are less susceptible to damage that could ca

42、use data loss.Capacity -Higher capacity is almost always preferred.Speed -Measured by its access time and data transfer rate.Fast storage devices are preferred.where the speed is determined by:Access time average time it takes a computer to locate data on the storage medium and read it.(1)Random acc

43、ess(also called“direct access”)“Jump”directly to the track or sector that holds the requested data.(2)Sequential access Read through the data from the beginning of the tape.Data transfer rate the amount of data that a storage device can move from the storage medium to the computer per second.CD-ROM

44、Technology-CD-ROM(Compact Disc Read-only Memory)contains data when it was manufactured.-Holds up to 680MB;-Read-only;-Not susceptible to humidity,fingerprints,dust or magnets;-relatively inexpensive to manufacture,make it an ideal way for SW publishers to distribute large programs and data files.-Th

45、e speed has increased.CD-R(compact disc-recordable)-Uses a CD-R drive,recording data on CD-R disks;-Allow to record data in multiple sessions;-Most of todays optical drives provide multi session support,but not that manufactured before 1998;-Slow,take from 20 to 60 minutes to record a full CD-R;-You

46、 cannot delete or change data once it has been recorded.-The disks produced on a CD-R device can be used on CD-ROM or DVD drive.CD-RW(compact disc-rewritable)-Allows you to write data on a CD-RW disks,then change that data;-Most of todays optical drives now read CD-RW disk;-Process of accessing,savi

47、ng and modifying data on CD-RW disk is relatively slow.It is not yet an acceptable substitute for a hard disk.DVD(digital video disc)Being designed to provide enough storage capacity for a full-length movie;Like CD-ROM,DVD-ROM does not allow you to add or change the data on the disk,but DVD-R,DVD-RW

48、 do.4.7GB storage;DVD drive can read data from CD-ROM,CD-R and CD-RW disks,but DVD disk cannot be read by CD-ROM,CD-R or CD-RW drives;Prediction:eventually these devices will be replaced by a single DVD device.What is solid state storage?Stores data in erasable,rewritable circuitry Flash memory Wide

49、ly used in portable consumer devices digital cameras,MP3,cell phones Portable,fast access to data ideal for mobile devices and transporting data2.4:Storage Devices How does solid state storage work?gridwork or circuitry Transistors(晶体管)act as gates gates open-“1”bit very litter power to open or clos

50、e the gate ideal for battery-operated devices(digital cameras)Non-volatile (chip retains the data)Fast access to data Downside Capacity(less than),cost(higher than that for magnetic or optical storage)2.4:Storage Devices USB flash drives are often designed with different cases What is a USB flash dr