Assembling an effective, efficient computer system requires an understanding of its relationship to the information system and the organization. The computer system objectives are subordinate to, but supportive of, the information system and the needs of the organization Describe how to select and organize computer system components to support information system (IS) objectives and business organization needs Principles of Information Systems, Seventh Edition

When selecting computer devices, you also must consider the current and future needs of the information system and the organization. Your choice of a particular computer system device should always allow for later improvements Describe the power, speed, and capacity of central processing and memory devices Describe the access methods, capacity, and portability of secondary storage devices Discuss the speed, functionality, and importance of input and output devices Identify popular classes of computer systems and discuss the role of each Principles of Information Systems, Seventh Edition

Computer Systems: Integrating the Power of Technology Special subsystem of an organization’s overall information system Integrated assembly of devices used to input, process, store, and output data and information Hardware Any machinery—most of which use digital circuits—that assists in the input, processing, storage, and output activities of an information system Principles of Information Systems, Seventh Edition

Hardware Components Central processing unit (CPU) Input devices Output devices Principles of Information Systems, Seventh Edition

Hardware Components (continued) Communications devices Primary storage devices Secondary storage devices Principles of Information Systems, Seventh Edition

Figure 3.1: Computer System Components Principles of Information Systems, Seventh Edition

Hardware Components in Action Step 1: Fetch instruction Step 2: Decode instruction Step 3: Execute instruction Step 4: Store results Principles of Information Systems, Seventh Edition

Figure 3.2: Execution of an Instruction Principles of Information Systems, Seventh Edition

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 Principles of Information Systems, Seventh Edition

Processing Characteristics and Functions Machine cycle time is measured in: Microseconds (1 millionth of a second) Nanoseconds (1 billionth of a second) Picoseconds (1 trillionth of a second) MIPS (Millions of Instructions Per Second) Principles of Information Systems, Seventh Edition

Processing Characteristics and Functions (continued) Clock speed: electronic pulses that affect machine cycle time Hertz (Hz): one cycle (pulse) per second Megahertz (MHz): millions of cycles per second Microcode: elementary circuits and logical operations a processor performs when executing instructions Principles of Information Systems, Seventh Edition

Figure 3.3: Clock Speed and the Execution of Microcode Instructions Principles of Information Systems, Seventh Edition

Wordlength and Bus Line Width Bit: a binary digit (0 or 1) Wordlength: number of bits the CPU can process at any one time Bus line: physical wiring that connects the computer system components Principles of Information Systems, Seventh Edition

Physical Characteristics of the CPU CPU: collection of digital circuits Electrical current flows through silicon Moore’s Law: transistor densities on a chip double every 18 months Superconductivity: property of certain metals that allows current to flow with minimal electrical resistance Optical processors: computer chips that use light waves instead of electrical current to represent bits Principles of Information Systems, Seventh Edition

Figure 3.4: Moore’s Law Principles of Information Systems, Seventh Edition

Complex and Reduced Instruction Set Computing Complex instruction set computing (CISC): chip design that places as many microcode instructions into the central processor as possible Reduced instruction set computing (RISC): chip design that involves reducing the number of microcode instructions built into a chip to an essential set of common microcode instructions Principles of Information Systems, Seventh Edition

Memory Characteristics and Functions: Storage Capacity Principles of Information Systems, Seventh Edition

Types of Memory Random access memory (RAM): temporary and volatile Types of RAM EDO (Extended Data Out) DRAM (Dynamic RAM) SDRAM (Synchronous DRAM) Principles of Information Systems, Seventh Edition

Types of Memory (continued) ROM (read-only memory): usually nonvolatile Types of ROM 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 Principles of Information Systems, Seventh Edition

Figure 3.5: Basic Types of Memory Chips Principles of Information Systems, Seventh Edition

Figure 3.6: Cache Memory Principles of Information Systems, Seventh Edition

Multiprocessing Multiprocessing: the simultaneous execution of two or more instructions at the same time Massively parallel processing Speeds processing by linking hundreds or thousands of processors to operate at the same time, or in parallel Can coordinate large amounts of data and access them with greater speed Principles of Information Systems, Seventh Edition

Figure 3.7: Massively Parallel Processing Principles of Information Systems, Seventh Edition

Secondary Storage Secondary storage: offers advantages of nonvolatility, greater capacity, and greater economy Access methods, storage capacities, and portability required are determined by the information system’s objectives Principles of Information Systems, Seventh Edition

Table 3.1: Cost Comparison for Various Forms of Data Storage Principles of Information Systems, Seventh Edition

Access Methods Sequential access: retrieval method in which data must be retrieved in order; devices used are called sequential access storage devices (SASDs) Direct access: retrieval method in which data can be retrieved in any order; devices used are called direct access storage devices (DASDs) Principles of Information Systems, Seventh Edition

Secondary Storage Devices Magnetic tapes Magnetic disks Virtual tape Optical discs Principles of Information Systems, Seventh Edition

Secondary Storage Devices (continued) Digital versatile disk (DVD) Magneto-optical (MO) disks Memory cards Flash memory Expandable storage Principles of Information Systems, Seventh Edition

Enterprise Storage Options Attached storage Network-attached storage (NAS) Storage area network (SAN) Principles of Information Systems, Seventh Edition

Figure 3.12: Storage Area Network Principles of Information Systems, Seventh Edition

Input and Output Devices: The Gateway to Computer Systems Through input and output devices, people provide data and instructions to computer and receive results from it Selection of input and output devices depends on organizational goals and information systems objectives Principles of Information Systems, Seventh Edition

Characteristics and Functionality Data: can be human- or machine-readable Data entry: process of converting human-readable data into machine-readable form Data input: involves transferring machine-readable data into the system Source data automation: involves capturing and editing data where the data is initially created and in a form that can be directly input to a computer Principles of Information Systems, Seventh Edition

Input Devices Personal computer input devices Keyboard Mouse Voice-recognition devices Digital computer cameras Terminals Principles of Information Systems, Seventh Edition

Input Devices (continued) Scanning devices Optical data readers Magnetic ink character recognition (MICR) devices Point-of-sale (POS) devices Automated teller machine (ATM) devices Principles of Information Systems, Seventh Edition

Input Devices (continued) Pen input devices Light pens Touch-sensitive screens Bar-code scanners Radio-frequency identification (RFID) Principles of Information Systems, Seventh Edition

Output Devices Display monitors Liquid crystal displays (LCDs) Active-matrix Passive-matrix Principles of Information Systems, Seventh Edition

Output Devices (continued) Organic light-emitting diodes (OLEDs) Printers and plotters Computer output microfilm (COM) devices Music devices Principles of Information Systems, Seventh Edition

Computer System Types, Selecting, and Upgrading Computers can be classified as either special purpose or general purpose Special-purpose computers: used for limited applications by military and scientific research groups General-purpose computers: used for a wide variety of applications Principles of Information Systems, Seventh Edition

Computer System Types Handheld computers Portable computers Thin client Desktop computers Principles of Information Systems, Seventh Edition

Computer System Types (continued) Workstations Servers Mainframe computers Supercomputers Principles of Information Systems, Seventh Edition

Selecting and Upgrading Computer Systems Hard drive considerations Main memory considerations Printer considerations DVD burners Principles of Information Systems, Seventh Edition

Summary Hardware: machinery that assists in the input, processing, storage, and output activities of an information system Hardware components include central processing unit (CPU), input and output devices, communications devices, primary storage devices, and secondary storage devices Random access memory (RAM): temporary and volatile Read-only memory (ROM): usually nonvolatile Principles of Information Systems, Seventh Edition

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, optical disks, and DVDs Enterprise storage options: attached storage, network- attached storage (NAS), and storage area network (SAN) Principles of Information Systems, Seventh Edition

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. Principles of Information Systems, Seventh Edition