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Chapter 4

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Computer Science
Computer Science 1033A/B

Chapter 4 hardware and software Why do you need to know about information technology?  Information technology  Y2K (year 2000) problem  Resulting of expensive computer memory in the early days of computing  Two-digit to store year values  Knowing something about where technology has been, can help us understand where technology is headed. Where did all this information technology stuff come from?  Early computers:  1939 – 1952  Complex and expensive  Single user  One program at a time  Housed at university  1947, EniacMark I  1952, Ferut at U of T  mainframes 主机: 1952 – present  First digital computers  Used in business and government  First generation, were based on now obsolete 过时的 vacuum tubes 真空管 technology  IBM 650 ($200,000 -- $400,000)  Add or subtract 16,000 numbers/second  Second generation mainframes introduced in the late 1950s used transistors 晶体管  Smaller, easier to maintain, reliable  These first and second generation machines were often sold without software: the assumption was that companies themselves would develop the programs they wanted to use on the computer.  The third generation of mainframe machines introduced in the mid-1960s including operating systems and multiprocessing.  Timesharing – many users could share the main processor at the same time.  Cost millions dollars  Mini-computers  Models such as the IBM Z96 still being used today  Fast processing, massive 大量的 storage  Microcomputers: 1975 – present  The first microcomputers, like the MITS Altair 8800 and Datapoint 2200, were developed in 1975.  These early microcomputers often had no display careen 显示小宗 or monitor and required users to develop their own programs.  By 1981, the microcomputers had developed enough for companies such as:  IBM, Apple, Compaq, and Texas Instruments to launch the personal computer (PC)  These microcomputers had monitors 显示器, integrated circuits 集成电路, key-board, portable floppy disks 便携式软盘, word processors 文字处理器, spreadsheets 电子表格, and other software.  Networking personal computers: 1985 – present  Local Area Networks (LANs)  Linking many PCs together  Shared access to data, printers and peripheral devices  Gave each computer a specific address and then was able to deliver requests for data to appropriate addresses.  Wide Area Networks (WANs)  The internet  Email  Web browsing Technology lessons  Technology advances  Moore’s law  Take advantage of the changes  Small is powerful  Use it anyway  Networking is the thing  Communication and collaboration What does a manager need to know about computer hardware?  Hardware consists of electronic components and related gadgetry that input, process, output, and store data according to instructions encoded in computer programs or software.  Central processing unit (CPU)  “Brains” of the computer  Speed (MHz)  Fast CPU needed for:  Complicated calculations and manipulations  Processing large graphics files  Special function cards  Augment basic capabilities 加强基本性能  Sound card  Provides better sound quality  Video card  Enhances clarity and speed of video display  Main memory  Size (MB, GB)  Speed  Increased amount of memory allows for many applications to be run at the same time  Hard drive 硬盘驱动器(magnetic disks 磁盘)  Provide long-term storage  Storage Capacity (size)  Affects performance  Data recorded in concentric circles 同心圆  Disks spin 磁盘旋转 and read/write heads move in/out  Time required to read data depends on:  Rotational delay  Seek time  Optical disks 光盘  Types  CDs  DVDs  Data stored differently  Different capacities and speed  ROM = read-only memory  R = record data once  RW = rewritable  Video displays  Two types  CRTs (Cathode ray tubes 阴极射线管)  Big and bulky 笨重  LCDs (Liquid crystal display 液晶显示器)  Slimmer  Specifications 产品规格  Screen 屏幕 size (in inches 英寸)  Resolution 分辨率 (in pixels 像素)  Pixels 像素  Single point on screen  Number of pixels depends  Size of monitor and creation of image  Resolutions  640 x 480, 800 x 600, 1024 x 768, 1280 x 1024... 1680 x 1050, 1920 x 1080  Optimal grid 最佳网格 for sharpness 锐度 and clarity 清晰度  Input, processing, output, and storage hardware  Input hardware devices 设备 include the keyboard, mouse, document scanners, and barcode条码 (universal product code) scanners like those used in grocery stores杂货 店.  Processing devices include the central processing unit (CPU), which is sometimes called the “brain” the computer.  The CPU selects instructions, processes them, performs arithmetic and logical comparisons, and stores results of operations in memory.  Output hardware consists of video displays, printers, audio speakers, overhead projects, and any other special-purpose devices.  Storage hardware saves data and programs.  Computer data  Binary digits  Computers represent data using binary digits, called bits.  A bit is either a zero or a one.  Sizing computer data  Bits are grouped into 8-bit chunks called bytes 字节.  Specifications for size of memory  K – kilobytes, 1024 bytes  MB – megabyte, 1024k bytes  GB – gigabyte, 1024MB bytes  TB – terabyte, 1024 GB  In 293 Words, how does a computer work?   The CPU is the major actor. To run a program, CPU must  First transfer the program or data from disk 磁盘 to main memory.  Then, to execute an instruction 执行一个指令, it moves the instruction form main memory into the CPU via 经由 the data channel 通道 or bus 总线.  The CPU has a small amount of very fast memory called a cache 高速缓存.  The computer main memory contains program instructions for Excel, Acrobat, and even a browser. It also contains instructions for the operating system (OS), which is a program has controls the computer’s resources as well as a block of data 数据块.  If there is not enough memory, it will remove something, perhaps the block of memory labeled More Excel, and then it will place the just-requested program or data into the vacated space 腾出的空间. This process is called memory swapping 内存交换.  Why should a manager care how a computer works?  The cache
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