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Chapter 2 - computers: the machines behind computing
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- 1chapter 2 - Computers: The machines behind computingasd
- 22.1 - defining a computer-dfa
- 3defn computer- is a machine that accepts data as input, processes data as input, processes data without human intervention by using stored instructions, and outputs information
- 4program-the step-by-step direction for performing a specific task, written in a language the computer can understand
-cant correct data, garbage in garbage out (GIGO) - 5two types of codes in a programsource code- is what the programmer writes, and the computer translates it into object code
-turned into binary - 6binary code-set of 0's and 1's
- 72-1a) components of a computer system notenote - main (primary) memory is where computers store data and instructions, similar to the human brain.
- 8Central processing unit-is the heart of a computer, it is divided into two components
- 9ALU - arithmetic logic unit- performs arithmetic operations, as well as comparison or relational operations; the latter are used to compare numbers
- 10control unit-tells the computer what to do, such as instructing the computer which device to read or send output to.
- 11single and multi processors- multiprocessors perform better than a single processor would perform, much like a team would perform better than a individual
- 12bus- is a link between devices connected to the computer. it can be parallel or serial, internal (local) or external.
- 13disk drive-is a peripheral device for recording, storing, and retrieving information
- 14CPU case- is also known as a computer chassis or tower. It is the enclosure containing the computers main components
- 15motherboard-is the main circuit board containing connectors for attaching additional boards. It usally contains the CPU, basic input/output system (BIOS), memory, storage, interfaces, serial and parellel port, expansion slots, and all the controllers for standard peripheral device, such as the display monitor, disk drive, and keyboard
- 162.2 - the history of computer hardware and software first generation- to make devlopments more clear, computers are often categorized into generations that mark technological breakthroughs
-vaccum tube big ass computers, overheated, unreliable, generated excessive heat, and were difficult to program - 17second generation-transitors that were easier to program
- 18third generation- integrated circuits, remote data entry, telecommunications
- 19fourth generation-miniaturization, VSLI, personal computers, optical disks
- 20fifth generation-parellel processing, gallium arsenide chips, optical technologies
- 21chapter 2page 29 after fifth generation
- 222-3 -power of computers-speed
-accuracy
-storage - 23bit and bytebit- one character of 0 or 1
byte - 8 bits
a byte consists of a single character
computer has 64 bits or 8 bytes - 24binary1 - on
0 - off - 25ASCIIamercian standard code for information internet change, 2^7 bits
- 26unicode and extended ASCII- 2^8 =256
- 272.4 - computer operations-computer can perform three basic functions
-arithmetic
-logical
-storage and retrival operations - 282.5 - input, output, and memory devicesadf
- 292-5a) input devices- send data and information to the computer. they are constantly being improved to make data input easier.
i.e- keyboard and mouse - 302-5b)output devices-is capable of representing information from a computer. the form of this output might be visual, audio, or digital, examples include printers, display monitors, and plotters
- 31soft copy-output on a screen is called a soft copy
- 32hard copy of a output device-most common on output device such as printers
- 332.5c) memory devices two types of memory-main memory and secondary memory
- 34main memory-stores data and information and is usally volatile; its contents are lost when electrical power is turned off. plays a major role in a computer performance
- 35secondary memory-which is nonvolatile, holds data when the computer is off or during the course of a program's operation. it also serves as archival storage
- 36random access memory- is volatile memory, in which data can be read from and written to; it is also called read-write memory
- 37cache ram-resides on the processor. because memory access from main RAM storage takes several clock cycles ( a few nanoseconds) cache RAM stores recently accessed memory so the processor is not waiting for the memory transfer
- 38Read-only memory-is non volatile; data cannot be written to ROM
- 39secondary memory devices three types-magnetic disk, magnetic tape, optical discs
- 40magnetic disk-made of mylar or metal , is used for random -access processing. in other words, data can be accessed in any order, regardless of its order on the surface
- 41magnetic tape-made of a plastic material, resembles a cassette tape and stores data sequentially
- 42optical discs-use laser beams to access and store data. examples includes CD - ROMS, WORM discs, and DVDs
- 43different types of secondary memory devices three typesWORM - write once and cannot be altered, SD is a type
CD-ROM - compact disc read - only memory
optical - can be erased and altered repeatedly - 44RAID - redundant array of independent disks (RAID)-system is a collection of disk drives used for fault tolerance and improved performance
- 45cloud storage-used for online storage and backup, involves multiple virtual servers that are usually hosted by third parties. customers buy or lease storage space from third parties based on their current or future needs
- 46storage area network- is a dedicated high-speed network consisting of both hardware and software used to connect and manage shared storage devices, such as disk arrays, tape libraries, and optical storage devices
- 47network-attached storage-is essentially a network-connected computer dedicated to providing file-based data storage services to other network devices
- 482.6 - classes of computersadd
- 49note-computers are getting faster.
-a notebook nowadays is faster at processing than a 1970's supercomputer
i.e - iPads help improve employee safety and monitoring, etc. - 502-6 a) server platforms: An overview server-is a computer and all the software for managing network resources and offering services to a network
- 51server platforms examplesapplications servers - store computer software, which users can access from their workstations
database servers - store massive amount of data for access from users computers
disk servers - large capacity hard-drive and enable users to store files and retrivals
-fax servers, file servers, mail servers, print servers - 522.7a) what is software?ass
- 53operating system-is a set of programs for controlling and managing computer hardware and software
-consists of control programs and supervisor programs - 54control programs-manage computer hardware and resources by performing the following functions
job management - control and prioritize tasks performed by the CPU
resource allocation- manage storage/mem
data management-check data for integrity
communication - between the I/O and CPU - 55supervisor program (kernel)-is responsible for controlling all other programs in the OS, such as compilers, interpreters, assemblers, and utilities for performing special tasks
-time-shared OS's allow several users to use computer resources simultaneously - 56note *-two new supervisor programs for the smartphone are IOS and android
- 572-7b) Application softwarecan be commercial software or software developed in house and is used to perform a variety of tasks on a personal computers
- 582.8 - computer languages-currently on the fifth generation of computer language
- 59machine language- the first generation of computer languages, consists of a series of 0's and 1's representing data and or instructions. it is dependent on the machine, so code written for one type of computer does not work on another type of computer
- 60assembly language-the second gen of computer language, higher-level language than machine language but it also machine dependent. it uses a series of short codes, or mnemonics, to represent data or instructions
- 61high-level languages-are machine independent and part of the third generation of computer languages. many languages are available , and each is designed of a specific purpose
i.e. - C++, VB.net - 624GL-use macro codes that can take the place of several lines of programming. the commands are powerful and easy to use, even with little training
- 635GL-use AI technologies, such as knowledge-based systems, natural language programming, and a graphical approach. these languages are designed to have natural conversations between you and the computer
- 64mark - up languages-not full-featured programming languages, HTML and XML
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- information systems Fichas sobre Chapter 2 - computers: the machines behind computing, creado por nathan fulcher el 18/09/2019.
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- nathan fulcher
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