Chapter 2Hardware

• Trends in Computing Systems

• Generally classified into three groups– Mainframe computers– Midrange (mini) computers– Microcomputers (PCs)

MicrocomputerApplications

• Often referred to as personal computers

• Many uses, styles, purposes

• Workstations - High power PCs used for analytical processing, mathematical calculations, statistical analysis

• Network Servers - Used to manage resources on a network (usually a Local Area Network)

Microcomputers (cont)

• Personal Digital Assistants - Highly specialized and mobile devises

• Use special software to allow for optical character recognition, touch pads, pen-based interface, etc.

• This is the latest trend in communications devices

Multimedia Systems

• Personal computers with a variety of media devices

• Allow for more robust displays, music, voice recognition and synthesis

• More expensive than a traditional machine, but much more useful and capable

Network computers

• Designed primarily for work situations where users access an Intranet (network using Internet technologies

• These machines usually have little or no disk storage space

• Main benefits are low cost, ease of upgrades, manageable

Computer terminals

• Dumb terminal - No processing occurs at the terminal level. Usually associated with a mainframe or client/server system

• Intelligent terminals - Have the capability to process at the local level (includes transaction terminals in grocery store, banks, department stores, etc)

Midrange Systems

• Multi user systems that manage network traffic, file access, device management

• More powerful than a personal computer

• Less powerful than a mainframe

• Less costly to purchase, operate, maintain

• Most efficient when scope of use is narrow but processing needs are high

Midrange (cont)

• Used largely in scientific research, process control situations, engineering (CAD, CAM, CAO)

• Sometimes used as front end processors to aid a mainframe system

• Good devices for telecommunications and network control (network servers)

Midrange (cont)

• Can be used to host an Intranet, Extranet, Internet, or client/server system

• Can be configured and programmed to operate virtually unaided

• Do not require special climate controlled areas

Mainframe Systems

• Physically larger than midrange, microcomputers, file servers

• Can process more data and faster

• Processing measured in MIPS (millions of instructions per second)

• High storage capacity

• Require climate controlled operating areas

Mainframe Applications

• Support the information and processing needs of large corporations, government offices, military

• Can handle vast computational tasks

• Super-server for communications need of large client/server networks

• Data warehousing

Supercomputer Applications

• Used by major universities, multinational corporations, largest government divisions

• Cooperative applications between countries

• Use multiple processors (any of which could constitute as a mainframe)

• $5million to $50 million cost

Components of a Computer System

• It is important to understand the components of a computer as a system

• Input > Processing > Output > Storage > Control

Input

• Input devices allow for the feeding of data to the computer system

• Keyboard/keypad

• Touch screen

• Light pens

• Mouse

• OCR

• Voice activation

Processing

• Central processing unit (microprocessor in a personal computer)

• Performs three functions– Control unit– Arithmetic-Logic unit– Primary storage unit

Output

• Processed data in the form designated by the user

• Devices include– video display (monitors)– Audio response– Printers

Storage

• Used to store programs (computer instructions), data, processed information

• Two types– Primary storage (main memory)– Secondary storage (magnetic disk, compact

disc, magnetic tape)

Control

• The control unit manages and interprets programs, transmission to other components of the system

• Is part of the CPU– other part is ALU– CPU contains cache memory

Primary Storage

• Main memory - microelectronic semiconductors

• Commonly known as RAM (random access memory)

• Sometimes main memory can use ROM (read only memory)

• Loss of data if power loss

Secondary storage

• Commonly known as permanent storage

• Physical storage versus electronic storage

• Support for primary storage

Multiple Processor Systems

• Some systems use more than one processor unit

• Several configurations

• Usually splits the control unit and the logic unit

Multi ProcessorConfigurations

• Support Processor - Free up the main processor to execute program instructions (can be a math co-processor, video display controller or magnetic disk controller)

• Coupled Processor - Used mostly to provide for fault tolerance

• Parallel Processors - Execute instructions in sequence

cont

• Massively Parallel Processors - Many processors aligned to execute hundreds or thousands of instructions at the same time

• RISC - Reduced Instruction Set Computer

• Uses less instructions

• Conclude chapter 2 next week

• Complete coverage of chapter 3 next week