Hardware: Input, Processing, and Output Devices

1. Chapter 3 Hardware: Input, Processing, and Output Devices

2. Computer System • Special subsystem of an organization's overall information system • Integrated assembly of physical devices, centered around at least one processing mechanism utilizing digital electronics • Used to input, process, store, and output data and information

3. Computer System Components [Figure 3.1] Computer system hardware components include devices that perform the functions of input, processing, data storage, and output.

4. Central Processing Unit (CPU) • Arithmetic/logic unit (ALU) • Performs mathematical calculations • Makes logical comparisons • Control unit • Sequentially accesses and decodes program instructions • Coordinates flow of data in and out of the ALU, registers, primary storage, secondary storage, output devices • Registers • High-speed storage areas • Temporarily hold small units of program instructions and data immediately before, during, and after execution by CPU

5. Primary Storage • Holds program instructions and data immediately before or immediately after the registers • Also called memory or main memory • Closely associated with the CPU

6. Execution of an Instruction • Instruction phase • Step 1: Fetch instruction • Step 2: Decode instruction • Instruction time (I-time): The time to complete the instruction phase

7. Execution of an Instruction • Execution phase • Step 3: Execute instruction • Step 4: Store results • Execution time (E-time): The time to complete the execution phase

8. Execution of an Instruction Fig 3.2

9. CPU Characteristics • Machine cycle time • Clock speed • Wordlength and bus line width • Physical characteristics • Complex and reduced instruction set computing

10. Machine Cycle Time • Measured in fractions of a second • Millisecond - one thousandth of one second • Microsecond - one millionth of one second • Nanosecond - one billionth of one second • Picosecond - one trillionth of one second • Or in terms of instructions per second • MIPS - millions of instructions per second

11. Clock Speed • Predetermined rate at which the CPU produces a series of electronic pulses • Microcode • Predetermined internal instructions executed in accordance with clock speed • Often measured in megahertz (MHz) or millions of cycles per second; ranges from 20 MHz to over 200 MHz for PCs

12. Clock Speed and the Execution of Microcode Instructions • [Figure 3.3]

13. Wordlengthand Bus Line Width • Bit • A binary digit: 0 or 1 • Wordlength • Number of bits the CPU can process at any one time • Bus lines • Physical wiring that connects computer system components

14. Physical Characteristicsof the CPU Moore’s Law: The hypothesis that transistor densities on a single chip will double every 18 months [Figure 3.4]

15. CISC and RISC • Complex instruction set computing (CISC) • Places as many microcode instructions into the central processor as possible • Reduced instruction set computing (RISC) • Reduces the number of microcode instructions built into a chip to an essential set of common instructions

16. Memory • Storage capacity • Byte = eight bits • Kilo, Mega, Giga, Tera • Types of memory • Random access memory (RAM) • Temporary and volatile • Read-only memory (ROM) • Permanent and non-volatile • Cache memory • High-speed, quicker access than main memory

17. Basic Types of Memory Chips

18. Cache Memory

19. Multiprocessing • Processing that occurs using more than one processing unit • Coprocessor • A processor that speeds processing by executing specific types of instructions while the CPU works on another processing activity

20. Parallel Processing Speeds processing by linking several processors to operate at the same time

21. Parallel Processing • Shared memory processing (SMP) • Involves fewer processors and a common pool of main memory • An independent task runs on each processor • Massively parallel processing (MPP) • Involves hundreds or thousands of microprocessor chips assigned to do the computing for a single program

22. Parallel Processing [Figure 3.8]

23. Secondary Storage • The portion of the computer that holds large amounts of data, instructions, and information more permanently than does main memory • Also called permanent storage

24. Cost Comparison of Various Forms of Data Storage [Figure 3.9]

25. Access Method Trade-Offs • Direct access • Process by which data and information are retrieved directly, without the need to pass by other data in sequence • Sequential access storage device (SASD) • Device used to sequentially access secondary storage media

26. Access Method Trade-Offs • Direct access storage device (DASD) • Device used to directly access secondary storage media

27. Secondary Storage Devices • Magnetic tape • Common secondary storage media • Mylar film coated with iron oxide • Magnetic disks • Steel platters (hard disks) or Mylar film (floppy disks) coatedwith iron oxide Fig. 3.11

28. Secondary Storage Devices • Redundant array of independent/ inexpensive disks (RAID) • Generates extra bits of data from existing data so the system can create a “reconstruction map” to rebuild lost data • Disk mirroring • Provides an exact copy of data on drive

29. Secondary Storage Devices • Optical disks • A rigid disk of plastic onto which data is recorded by special lasers that physically burn pits into the disk • Compact disk read-only memory (CD-ROM) • A common form of optical disk on which data, once recorded, cannot be modified

30. Secondary Storage Devices • CD-rewriteable (CD-R) • Allows PC users to replace their diskettes with high capacity CDs that can be written upon and edited over • Write-once, read-many (WORM) • Allows businesses to record customized data and information onto an optical disk

31. Secondary Storage Devices • Magneto-optical disk • A hybrid between magnetic disks and optical disks • Digital video disk (DVD) • Looks like a CD-ROMdisk, but can store about 135 minutes of digital video Fig. 3.12

32. Secondary Storage Devices • Memory cards • Credit-card sized devices that can be installed in an adapter or slot in many personal computers • Flash memory • A silicon chip that is nonvolatile and keeps its memory when the power is shut off

33. Secondary Storage Devices • Expandable storage • Storage devices that use removable disk cartridges Fig. 3.13

34. Secondary Storage Devices • Floptical disk • Experimental storage device that is the same size as a diskette, but is able to hold many more times the data

35. Comparison of Secondary Storage Devices [Table 3.2]

36. Speed And Functionality • The nature of data • Human-readable data vs. machine-readable data • Data entry and input • Data entry: Human-readable data is converted into a machine-readable • Data input: Machine-readable data is transferred into the system continued...

37. Speed And Functionality • Source data automation • Automation of data entry and input where the data is created, thus ensuring accuracy and timeliness

38. Personal computer input devices Keyboard Mouse Voice recognition devices Digital computer cameras Terminals Scanning devices Optical data readers Optical mark recognition readers Optical character reader Input Devices continued...

39. Magnetic ink character recognition (MICR) devices Point-of-sale (POS) devices Automatic teller machine (ATM) devices Pen input devices Light pens Touch-sensitive screens Bar code scanners Input Devices

40. Sample Input Device: Digital Computer Camera Fig. 3.14

41. Sample Input Device: MICR Device Fig. 3.15

42. Output Devices: Monitors • Display monitors • Monochrome • RGB (red, green, blue) • Color graphics adapter (CGA) • Enhanced graphics adapter (EGA) • Video graphics array (VGA) • Extended graphics array (XGA) • Liquid crystal display (LCDs)

43. Output Devices: Printers, Plotters,and Microfilm • Impact printers • Letter-quality printers, dot-matrix printers, near-letter quality printers (NLQ) • Non-impact printers • Ink-jet printers and laser printers • Plotters • Computer output microfilm devices (COM) • Special-Purpose Devices: Multifunction device • A device that combines several input/output devices (e.g., printer, fax, scanner)

44. Classifying Computers • Special-purpose computers • Used for limited applications • General-purpose computers • Most common type of computers • Used for a variety of applications

45. Types of Computer Systems • Personal computers • Network computers • Workstations • Midrange computers • Mainframes • Supercomputers

46. Types of Computer Systems • Personal computers • Relatively small and inexpensive • Also called microcomputers

47. Computer System Types • Network Computers • Stripped-down personal computers • Primarily used with network system and the Internet • Workstations • Fit between high-end microcomputers and low-end midrange computers in terms of cost and processing power

48. Computer System Types • Midrange computers • Systems that can accommodate several users at one time • Formerly known as minicomputers • Mainframes • Large powerful computers often shared by hundreds of concurrent users connected to the machine via terminals • Supercomputers • Most powerful computer systems with the fastest processing speeds

49. Processor speed 1-5 MIPs Amount of RAM 4-16 MB Approximate cost $500-$1,500 How used Supports data entry Connects to the Internet Example Oracle Network computer Network Computer

50. Processor speed 5-20 MIPs Amount of RAM 16-128 MB Approximate cost $1,200-$5,000 How used Improves individual worker’s productivity Example Compaq Pentium computer Personal Computer