Principles of Information Systems Eighth Edition Chapter 3 Hardware: Input, Processing, and Output Devices

Principles of Information Systems

Eighth Edition

Chapter 3

Hardware: Input, Processing, and Output Devices

Principles of Information Systems, Eighth Edition 2

Principles and Learning Objectives

• Assembling an effective, efficient set of computer hardware devices requires understanding their role in supporting the underlying information systems and the needs of the organization; the computer hardware objectives are subordinate to, but supportive of, the information systems and the needs of the organization– Describe how to select and organize computer

hardware components to support information system (IS) objectives and business needs


Principles and Learning Objectives (continued)

• When selecting computer hardware, you must consider the current and future needs of the information systems and the organization; your choice of a hardware device should always allow for later improvements to meet evolving organizational needs– Describe the power, speed, and capacity of central

processing and memory devices– Describe the access methods, capacity, and

portability of secondary storage devices


Principles and Learning Objectives (continued)

– Discuss the speed, functionality, and importance of input and output devices

– Identify popular classes of computer systems and discuss the role of each


Why Learn About Hardware?

• Can improve productivity, increase revenue, reduce costs, and provide better service

• Managers are expected to know about hardware– To help define business needs– To ask questions and evaluate options when buying

equipment


Introduction

• Hardware: any machinery (most of which use digital circuits) that assists in the input, processing, storage, and output activities of an information system

• When making hardware decisions, businesses must consider how the hardware can support:– Objectives of the information system– Goals of the organization


Computer Systems: Integrating The Power of Technology

• Choosing the right computer hardware requires understanding its relationship to the information system and needs of the organization

• Hardware objectives are subordinate to, but supportive of, the information system and the current and future needs of the organization


Hardware Components

• Central processing unit (CPU)

• Input devices

• Output devices


Hardware Components (continued)

• Communications devices

• Primary storage devices

• Secondary storage devices


Hardware Components (continued)

Figure 3.1: Hardware Components


Central processing unit (CPU)

The part of the computer that consists of three associated elements: the arithmetic/logic unit, the control unit, and the register areas.

• arithmetic/logic unit (ALU) : The part of the CPU that performs mathematical calculations and makes logical comparisons.



• control unit: The part of the CPU that sequentially accesses program instructions, decodes them, and coordinates the flow of data in and out of the ALU, Registers, primary storage, and even secondary storage and various output devices.



• Register: A high-speed storage area in the CPU used to temporarily hold small units of program instructions and data immediately before, during, and after execution by the CPU.

• primary storage (main memory; memory): The part of the computer that holds program instructions and data.


Hardware Components in Action

• Step 1: Fetch instruction

• Step 2: Decode instruction

• Step 3: Execute instruction

• Step 4: Store results



• Step 1: Fetch instruction. The computer reads the next program instruction to be executed and any necessary data into the processor.

• Step 2: Decode instruction. The instruction is decoded and passed to the appropriate processor execution unit.



• Each execution unit plays a different role: – The arithmetic/logic unit performs all arithmetic

operations, – the floating-point unit deals with noninteger

operations



– the load/store unit manages the instructions that read or write to memory,

– etc.

• The time it takes to perform the instruction phase (Steps 1 and 2) is called the instruction time

(I-time).



• Step 3: Execute instruction. The hardware element, now freshly fed with an instruction and data, carries out the instruction. This could involve making an arithmetic computation, logical comparison, bit shift, or vector operation.



• Step 4: Store results. The results are stored in registers or memory.

• The time it takes to complete the execution phase (Steps 3 and 4) is called the execution time

(E-time).



• After both phases have been completed for one instruction, they are performed again for the second instruction, and so on.

• Completing the instruction phase followed by the exe cution phase is called a machine cycle. Some processing units can speed processing by using pipelining, whereby the processing unit gets one instruction, decodes another, and executes a third at the same time.


Hardware Components in Action (continued)

Figure 3.2: Execution of an Instruction


Processing and Memory Devices: Power, Speed, and Capacity

• System unit– Houses the components responsible for processing

(the CPU and memory)

• All other computer system devices are linked either directly or indirectly into the system unit housing


Processing Characteristics and Functions

• Machine cycle time is measured in:– Nanoseconds (1 billionth of a second)– Picoseconds (1 trillionth of a second)– MIPS (millions of instructions per second)


Processing Characteristics and Functions (continued)

• Clock speed: series of electronic pulses produced at a predetermined rate that affects machine cycle time– Often measured in:

• Megahertz (MHz): millions of cycles per second

• Gigahertz (GHz): billions of cycles per second

• Microcode: predefined, elementary circuits and logical operations that the processor performs when it executes an instruction



• The control unit executes the microcode in accordance with the electronic cycle, or pulses of the CPU "clock." Each microcode instruction takes at least the same amount of time as the interval between pulses. The shorter the interval between pulses, the faster each microcode instruction can be executed.



• Because the number of microcode instructions needed to execute a single program instruction-such as performing a calculation or printing results-can vary, the clock speed is not directly related to the true processing speed of the computer.



• As the clock speed of the CPU increases, additional heat is generated that can corrupt the

data and instructions the computer is trying to process. Because this can lead to errors that cause a program to behave erratically, chip and computer

manufacturers must be wary of potential heat problems in their new designs.


Physical Characteristics of the CPU

• Most CPUs are collections of digital circuits imprinted on silicon wafers, or chips, each no

bigger than the tip of a pencil eraser.

• To turn a digital circuit on or off within the CPU, electrical current must flow through a medium

(usually silicon) from point A to point B.

• The speed the current travels between points can be increased by either reducing the distance

between the points or reducing the resistance of the medium to the electrical current.


Physical Characteristics of the CPU

• Digital circuits on chips

• Electrical current flows through silicon

• Moore’s Law: transistor density of chips will double every 18 months


Physical Characteristics of the CPU (continued)

Figure 3.3: Moore’s Law


Memory Characteristics and Functions

• Main memory– Located physically close to the CPU, but not on the

CPU chip itself– Rapidly provides data and instructions to the CPU


Storage Capacity

Table 3.1: Computer Storage Units


Types of Memory

• Random access memory (RAM) – Temporary and volatile

• Types of RAM – EDO (Extended Data Out) – DRAM (Dynamic RAM) – SDRAM (Synchronous DRAM)


Types of Memory (continued)

• Types of nonvolatile memory– ROM (read-only memory)– PROM (programmable read-only memory)– EPROM (erasable programmable read-only

memory)

• Cache memory: high-speed memory that a processor can access more rapidly than main memory



Figure 3.4: Basic Types of Memory Chips



Figure 3.5: Cache Memory



• Because cache memory holds less data, the CPU can access the desired data and instructions more quickly than selecting from the larger set in main memory. Thus, the CPU can execute instructions faster, improving the overall performance of the computer system.


Types of Memory (continued)• There are three types of cache memory.• The Level 1 (LI) cache is on the CPU chip. • The Level 2 (L2) cache memory can be accessed by

the CPU over a high-speed dedicated interface. The latest processors go a step further and place the L2 cache directly on the CPU chip itself and provide high-speed support for a tertiary Level 3 (L3) external cache. Deerfield, the low-power version of Intel's 64-bit servers called the Itanium 2 chip, was introduced with 1.5 MB of Level 3 cache.



• When the processor needs to execute an instruction, the instruction's operation code indicates whether the data will be in a register or in memory. If the operation code specifies a register as the source, it is taken from there. Otherwise, the processor looks for the data in the LI cache, then the L2 cache, and then the L3 cache. If the data is not in any cache, the CPU requests the data from main memory. If the data is not even stored in main memory, the system has to retrieve the data from secondary storage.


Types of Memory (continued)• It can take from one to three clock cycles to fetch

information from the LI cache, while the CPU waits and does nothing. It takes 6 to 12 cycles to get data from an L2 cache on the processor chip. It can take dozens of cycles to fetch data from an L3 cache and hundreds of cycles to fetch data from secondary storage.

• Because this hierarchical arrangement of memory helps the CPU find data faster, it bridges a widening gap between processor speeds


Multiprocessing

• Multiprocessing: simultaneous execution of two or more instructions at the same time

• Multiprocessing using coprocessors– Coprocessor: speeds processing by executing

specific types of instructions while the CPU works on another processing activity


Multiprocessing

• Coprocessors can be internal or external to the CPU and can have different clock speeds than the CPU. Each type of coprocessor performs a specific function.

• A multicore microprocessor combines two or more independent processors into a single computer so that they can share the workload and boost processing capacity. a dual-core processor enables people to perform multiple tasks simultaneously .


Parallel Computing

• Parallel computing: simultaneous execution of the same task on multiple processors to obtain results faster

• Massively parallel processing:– Speeds processing by linking hundreds or thousands

of processors to operate at the same time, or in parallel

– Each processor has its own bus, memory, disks, copy of the operating system, and applications


Parallel Computing (continued)

• Different approaches to achieving parallel computing– Single instruction/multiple data (SIMD) parallel

processors – Multiple instruction/multiple data (MIMD) parallel

processors

• Grid computing: use of a collection of computers, often owned by multiple individuals or organizations, to work in a coordinated manner to solve a common problem


Parallel Computing (continued)

• The most frequent business uses for parallel computing include:– modeling.– simulating.–analyzing large amounts of data


Secondary Storage

• Compared with memory, offers the advantages of nonvolatility, greater capacity, and greater economy

• Access methods, storage capacities, and portability required are determined by the information system’s objectives


Access Methods

• Sequential access: records must be retrieved in order– Devices used are called sequential access storage

devices (SASDs)

• Direct access: records can be retrieved in any order– Devices used are called direct access storage

devices (DASDs)


Devices

• Magnetic tapes

• Magnetic disks

• RAID

• Virtual tape

• Optical disks


Devices (continued)

• Digital video disk (DVD)

• Holographic Versatile Disc (HVD)

• Memory cards

• Flash memory


Enterprise Storage Options

• Attached storage

• Network-attached storage (NAS)

• Storage area network (SAN)


Enterprise Storage Options (continued)

Figure 3.9: Storage Area Network


Input and Output Devices: The Gateway to Computer Systems

• Through input and output devices, people provide data and instructions to the computer and receive results from it

• Selection of input and output devices depends on organizational goals and IS objectives


Characteristics and Functionality

• Data can be human-readable or machine-readable

• Data entry: converts human-readable data into machine-readable form

• Data input: transfers machine-readable data into system

• Source data automation: capturing and editing data where the data is initially created and in a form that can be directly input to a computer


Input Devices

• Personal computer input devices– Keyboard– Mouse

• Speech-recognition technology

• Digital cameras

• Terminals


Input Devices (continued)

• Scanning devices

• Optical data readers

• Magnetic ink character recognition (MICR) devices

• Magnetic stripe card

• Point-of-sale (POS) devices


Input Devices (continued)

• Automated teller machine (ATM) devices

• Pen input devices

• Touch-sensitive screens

• Bar-code scanners

• Radio Frequency Identification (RFID)


Output Devices

• Display monitors

• Liquid crystal displays (LCDs)

• Organic light-emitting diodes (OLEDs)

• Printers and plotters

• Digital audio player


Special-Purpose Input and Output Devices

• Computer-based navigation systems

• Multiple function printers

• Eyebud screens


Computer System Types, Selection, and Upgrading

• Special-purpose computers: used for limited applications by military and scientific research groups

• General-purpose computers: used for a wide variety of applications


Computer System Types

• Handheld computers

• Portable computers

• Thin client

• Desktop computers


Computer System Types (continued)

• Workstations

• Servers

• Mainframe computers

• Supercomputers


Selecting and Upgrading Computer Systems

• Dispose of old equipment properly

• Consider factors such as speed, cost, and performance when upgrading– Hard drive – Main memory– Printer– DVD burners


Summary

• Hardware: machinery that assists in the input, processing, storage, and output activities of an information system

• Hardware components: central processing unit (CPU), input and output devices, communications devices, primary storage devices, and secondary storage devices

• Random access memory (RAM): temporary and volatile

• ROM (read-only memory): nonvolatile


Summary (continued)

• Multiprocessing: simultaneous execution of two or more instructions at the same time

• Sequential access: records must be retrieved in order

• Direct access: records can be retrieved in any order

• Examples of secondary storage devices: magnetic tapes and disks, DVDs, memory cards, etc.

• Enterprise storage options: attached storage, network-attached storage (NAS), and storage area network (SAN)


Summary (continued)

• Examples of input devices: keyboards, mice, voice-recognition devices, terminals, scanning devices, and touch-sensitive screens

• Examples of output devices: display monitors, liquid crystal displays (LCDs), printers, and plotters

• Computers can be classified as either special-purpose or general-purpose

• Computer system types: handheld computers, portable computers, desktop computers, workstations, servers, etc.

Documents

Principles of Information Systems Eighth Edition Chapter 3 Hardware: Input, Processing, and Output Devices