MIS 175 Spring 20021 Learning Objectives When you finish this chapter, you will: –Recognize major components of an electronic computer. –Understand how

MIS 175 Spring 2002 1

Learning Objectives

• When you finish this chapter, you will:– Recognize major components of an

electronic computer.– Understand how the different

components work.– Know the functions of peripheral

equipment.


Learning Objectives• Be able to classify computers into

major categories, and identify their strengths and weaknesses.

• Be able to identify and evaluate key criteria when deciding what computers to purchase.


The Central Tool of Modern Information Systems

• Four Basic Functions of Computers– Accept data– Process data– Store data and instructions– Output data



Figure 4.1 All computers have the same basic components.



Figure 4.2 Organizations have moved from using large mainframes to using networked PCs.



Figure 4.3 A timeline of computing



Figure 4.3 (continued) A timeline of computing


Computers Communicating: Bits And Bytes

• Computer recognizes two states: on or off– Each on or off signal represents a bit (binary

digit)

• Encoding Schemes– Representation of symbols by unique strings

of bits

• Counting Bases– Decimal system is “base 10”– Binary system is “base 2”

• Used by computers


Computers Communicating: Bits And Bytes

Figure 4.4 Binary encoding schemes


A Peek Inside the Computer

Figure 4.5 A look inside a computer



• The Central Processing Unit (CPU)– The brain of the computer– Microprocessor

•Carries signals that execute all processing

– Two Components:•Control unit•Arithmetic logic unit (ALU)



• Microprocessor

– Silicon chip embedded with transistors, or semiconductors

Figure 4.6 Schematic of how circuits on a chip would be open and closed to represent the letter D in EBCDIC (11000100)



Figure 4.7 What happens inside the CPU in one machine cycle executing the operation 7 + 5



• Machine Cycle– CPU’s execution of four functions:

•Fetch•Decode•Execute•Store


Time Measurements

Functions measured in small fractions of a second

“Clock speed” determines the number of the smallest operations performed per second

Figure 4.8 Computer time


Speed Measurements

Measured in terms of cycles per second

1 hertz (Hz) = one clock cycle per second1 MHz (megahertz) = 1,000,000 clock cycles per

second (1 million)1 GHz (gigahertz) = 1,000,000,000 clock cycles

per second (1 billion)


Moore’s Law

• States that– Chip density will double every 18

months

• This has driven incredible decreases in cost per unit of computing power and memory



• Memory– CPU Registers (part of the CPU)– Internal Memory

•Random access memory (RAM)•Read-only memory (ROM)


A Peek Inside the Computer• Computer Power

– Clock rate (measured in cycles per second)

– Amount of information the CPU can process in each cycle•This is determined by the word length and bus size

– Effective speed determined only by combination of both factors


Input Devices

• Keyboard• Mouse, Trackball, and Track Pad• Touch Screen• Source Data Input Devices• Imaging• Speech Recognition


Input Devices

Figure 4.9 Banks use magnetic-ink character recognition (MICR) to automate their input procedures.


Output Devices

• Soft-Copy Output Devices– Cathode-Ray Tube (CRT) Monitor– Flat-Panel Monitor– Speech Output

• Hardcopy Output Devices– Nonimpact Printers (most common)– Impact Printers


External Storage Media

External Memory (Storage)•Magnetic disks, magnetic tapes, optical discs

• Important Properties to Consider– Capacity– Speed– Cost– Reliability and permanence



• Magnetic Tapes • Magnetic Disks • Optical Discs (Compact Discs)• Optical Tapes


External Storage Media• Business Considerations of

Storage Media– Trade-offs– Modes of Access

•Sequential Access•Direct Access



Figure 4.11 Characteristics of storage media for business consideration



Figure 4.12 Sequential and random data organization


Classification of Computers

• Supercomputers– The largest, most powerful, and most

expensive– Used by universities, research institutions,

large corporations, and the military

• Mainframe Computers– Less powerful and less expensive than

supercomputers– Used by businesses with large amounts of data

that need to be stored in a central computer



• Minicomputer– Often used as the host computer in

a network of smaller computers– Priced in the tens of thousands to a

few hundred thousand dollars– Manufacturers: Compaq (VAX), IBM

(AS/400), and Hewlett-Packard



• Servers– Minicomputers used for specialized

purposes on a network– Example: file server, printer server,

database server, web server– Optimized for processing tasks and

I/O with other computers

MIS 175 Spring 2002 31Figure 4.13 PC sales continue to grow.


• Personal Computers / Clients

• Laptop and Handheld Computers


Importance of Standards

• Compatibility– Software and peripheral devices from one

computer can be used with another computer.– In a networked environment, computers need

to communicate to share databases and other computing resources.

– In addition to power and cost, compatibility is an extremely important factor in purchasing decisions.


Considerations in Purchasing Hardware

• What should you consider when buying personal computers?– Power -- speed, size of memory, storage

capacity– Expansion and upgrade capability– Ports for external devices like printers, hard

disks, communication devices– Ergonomics: Keyboard, Monitor– Vendor reliability, warranty policy, vendor

support

Documents

MIS 175 Spring 20021 Learning Objectives When you finish this chapter, you will: –Recognize major components of an electronic computer. –Understand how