Management Challenge. Managing Hardware Assets. Central Processing Unit. What is a Computer System?

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1 Management Challenge Managing Hardware Assets What computer processing and storage capability does our organization need to handle its information and business transactions? What arrangement of computers and computer processing would best benefit our organization? What kinds of software and software tools do we need to run our business? What criteria should we use to select our software technology? Of what new software technologies should we be aware? How would they benefit our organization? How should we acquire and manage the firm s hardware and software assets? M7011 Peter Lo M7011 Peter Lo What is a Computer System? Central Processing Unit A contemporary computer system consists of: Central Processing Unit Primary Storage Secondary Storage Input Devices Output Devices Communication Devices Central Processing Unit (CPU), also called Processor. Manipulates raw data into a more useful form and control other parts of the computer system. Interprets and carries out basic instructions that operate a computer M7011 Peter Lo M7011 Peter Lo

2 Central Processing Unit The CPU is the part of the computer system where the manipulation of symbols, numbers, and letters occurs and it control other parts of the computer system. Microprocessor (or computer on a chip) is a computer processor (also called a microchip) with Very Large Scale Integrated Circuit technology that integrates the computer memory, logic, and control on a single chip. Components of the CPU The CPU consists two major components: Arithmetic-logic unit (ALU): performs the computer s principal logic and arithmetic operations Control Unit: coordinates and controls the other parts of the computer system M7011 Peter Lo M7011 Peter Lo Control Unit Directs and coordinates operations in computer Control unit repeats four basic operations: Fetch Obtain program instruction or data item from memory Decode Translate instruction into commands Execute Carry out command Store Write result to memory M7011 Peter Lo Arithmetic/Logic unit (ALU) CPU component that performs execution part of the machine cycle Arithmetic (addition, subtraction, multiplication, and division) Comparison (greater than, equal to, or less than).or..and..not. Logical (AND, OR, NOT) M7011 Peter Lo

3 Machine Cycle (Instruction Cycle) Machine Cycle (Instruction Cycle) Machine Cycle is a series of operations required to process a single machine instruction. It is the time period during which one instruction is fetched from memory and executed. Execution Time (Time taken to execute and store) Execution Time (Time taken to execute and store) There are typically 4 stages of an instruction cycle that the CPU carries out: 1. Fetch the instruction from memory into the instruction register. 2. Decode the instruction. 3. Read the effective address from memory if the instruction has an indirect address. 4. Execute the instruction. Steps 1 and 2 are called the fetch cycle and are the same for each instruction. Steps 3 and 4 are called the execute cycle and will change with each instruction. M7011 Peter Lo M7011 Peter Lo Two Designs used for the CPU RISC (Reduced Instruction Set Computing) A technology which enhance speed of microprocessors by embedding only the most frequently used instructions on a chip. CISC (Complex Instruction Set Computing) In a CISC architecture, the CPU supports as many as two hundred instructions in a chip. What is storage? Media and devices used to store and retrieve data, instructions, and information M7011 Peter Lo M7011 Peter Lo

4 Primary Storage Primary Storage temporarily stores data and program instructions during processing Primary Storage Primary storage (also known as primary memory or main memory) has three functions. It stores All or part of the program that is being executed. The operating system programs that manage the operation of the computer The data that are being used by the program. M7011 Peter Lo M7011 Peter Lo Primary Storage RAM RAM (Random Access Memory) is primary storage of data or program instruction that can directly access any randomly chosen location in the same amount of time. Primary Storage ROM ROM (Read Only Memory) contains data and program instruction. Once data has been written onto a ROM chip, it can only be read from; that cannot be written to or removed. ROM retains its contents even when the computer is turned off. ROM is referred to as being nonvolatile, whereas RAM is volatile. M7011 Peter Lo M7011 Peter Lo

5 Primary Storage PROM PROM (Programmable Read Only Memory) is a kind of ROM clip used as control devices because it can be programmable once. Primary Storage EPROM EPROM (Erasable Programmable Read Only Memory) is a kind of ROM clip that can be erased and re-programmed many times. M7011 Peter Lo M7011 Peter Lo Primary Storage Register Register is the temporary storage location in the ALU or Control Unit where small amount of data and instruction reside just before use. Secondary Storage Secondary Storage such as magnetic disk, optical disk and magnetic tape, stores data and programs that are not being used in processing. M7011 Peter Lo M7011 Peter Lo

6 Secondary Storage Type of Secondary Storage Information System need to store information outside of the computer in a nonvolatile state (not required electrical power) and store volume of data too large to fit into a computer. The relatively long term storage of data outside the CPU and primary storage is called secondary storage. Magnetic disk: Floppy disk, Hard disk Optical Disks: CD-ROM, DVD Magnetic Tape: Inexpensive, older secondary-storage medium New Storage Alternatives: Storage Area Networks (SAN) M7011 Peter Lo M7011 Peter Lo Example of Secondary Storage What is an Input Device? DVD (Digital Video Disk), DVD-ROM, DVD+/- CD-ROM, WORM (Write Once/Read Many), CD-R (Compact Disk- Recordable) and CD-RW (Compact Disk-Rewritable) Personal Computer Memory Card International Association (PCMCIA) cards or PC cards Flash Cards or Flash Memory Compact Flash (CF) cards Smart Media Memory Sticks Magnetic Tape Direct Access Storage Device (DASD) Redundant array of inexpensive disks (RAID) Storage Area Network (SAN) Network Attached Storage (NAS) M7011 Peter Lo Input Devices such as a keyboard or mouse, convert data and instructions into electronic form for input into the computer M7011 Peter Lo

7 Principal Input Devices What is an Output Device? Output Devices such as printers, video display units and audio outputs convert electronic data produced by the computer system and display/output to the form that people can understand. M7011 Peter Lo M7011 Peter Lo Principal Output Devices Communication Devices Communication Devices provide connections between the computer and communications networks. Buses are paths for transmitting data and (control) signals among the parts of the computer system. M7011 Peter Lo M7011 Peter Lo

8 How Computers Represent Data? All symbols, pictures or words are in binary digits. A binary digit is called a bit and represents either a 0 or 1. In term of computer system, the presence of electronic or magnetic signal means one, and its absence indicates zero. A string of eight bits (usually) that computer stores as a unit is called a byte. Each byte can be used to store a decimal number, a symbol or character, or a part of a picture. on Popular Coding Systems to Represent Data ASCII American Standard Code for Information Interchange EBCDIC Extended Binary Coded Decimal Interchange Code off M7011 Peter Lo M7011 Peter Lo ASCII (American Standard Code for Information Interchange) Developed by the American National Standards Institute (ANSI) to provide a standard code that could be used by many different manufacturers in order to make machinery compatible. Originally designed as 7-bit code (plus the 8th party bit), but most computers now used the 8-bit code version (with extended code) Used in PCs and some other computer (e.g. UNIX-based) EBCDIC (Extended Binary Coded Decimal Interchange Code) Developed by IBM in the 1950s, and it represents every number, alphabetic character, or special character with 8 bits. Used in IBM mainframe M7011 Peter Lo M7011 Peter Lo

9 The Computer s Family Tree Computer Generations First Generation Computer Vacuum Tube Technology, Second Generation Computer Transistors, Third Generation Computer Integrated Circuits, Fourth Generation Computer VLSI (Very Large Scale Integrated Circuits), 1980-Present M7011 Peter Lo M7011 Peter Lo Different Types of Computer Microcomputers or Personal Computer (PC) Supercomputers Mainframes Midrange computers Minicomputers Portable computers Laptop computers Notebook computers Handheld computers Palmtop computers Server and Workstations Server Provides software and other resources to computers over a network Server Farm Large group of servers maintained by a commercial vendor, available for electronic commerce and other activities Workstation Desktop computer with powerful graphics and mathematical capabilities M7011 Peter Lo M7011 Peter Lo

10 Different Types of Processing Distributed Processing Distribution of processing work among multiple computers Centralized Processing Accomplished by one large central computer Client/Server Computing Splits processing between Clients and Servers on network Parallel Processing Parallel Processing is a type of processing in which more than one instruction can be processed at a time by breaking down a problem into smaller parts and processing them simultaneously with multiple processors. M7011 Peter Lo M7011 Peter Lo Batch and On-line Input processing Batch Processing A method of collecting and processing data in which transactions are accumulated and stored until a specified time when it is convenient or necessary On-line Processing Transactions are entered directly into computer and processed immediately M7011 Peter Lo