Chapter 2: Computers Flashcards
A computer consist of (4 components)
- Central processing Unit (CPU)
- Input/Output Units (I/O)
- Main (Primary) memory (storage)
- Auxiliary (secondary) storage
Central Processing Unit (CPU)
- Brain of the computer
- Processes data
- Executes programs stored in main memory by fetching instructions, examining them, and executing them
- Contains the logic of the machine
- Consists of the arithmetic logic unit (ALU), control unit, and two registers (Instruction and program counter)
Logic
- Ability of a computer to follow instructions
- Stored in Central Processing Unit (CPU)
Central Processing Unit (CPU) consists of (3 things)
- Control unit
- Arithmetic Logic Unit
- Registers (2 of them: instruction and program counter)
Control unit of a Central Processing Unit (CPU)
- Fetches program instructions (e.g. PRINT, INPUT) from main memory and determines their type and supervises their execution.
- Tells the computer what to do
- Ex: Such as instructing the computer which device to read or send output to
Arithmetic/Logic Unit (ALU) of a Central Processing Unit (CPU)
Performs operations: (+,-,*,/) and comparisons (,=) needed to carry out the instructions
Registers In a Central Processing Unit (CPU)
- Small very high-speed storage used to store temporary results and certain control information
- Instruction and Program counter registers
Instruction Register
Holds the instruction which is currently being executed
Program Counter (Instruction Location Counter) (Address Register)
Points to the instruction which will be executed next
Computer Program (Also called source code)
- Step-by-step directions for performing a specific task (instructions)
- Written in a language the computer can understand
- Also called a source code
- Source code must be translated into object code, consisting of binary 0s and 1s
Other things computer have
- Hardware: Physical devices such as keyboards, monitors, and processing units
- Software: Programs written in computer languages
- Single or multiprocessors (multiprocessing: use of 2+ CPU’s in a computer system)
Bus
Link (wire) between devices connected to the computer
Disk Drive
Peripheral device (device that connects to the computer) for recording, storing, and retrieving information
CPU case (computer chassis/tower)
- Enclosure containing the computer’s main components
- Also called computer chassis or tower
Motherboard
Main circuit board containing connectors for attaching additional boards
3 basic operations of a computer
- Arithmetic operations
- Logical operations
- Storage and retrieval operations. Data is stored in bits
Main/core/primary Memory
- Stores data and information, application programs, and operating systems and other system software
- Volatile (Contents are lost when electrical power is turned off)
Secondary Memory
- Nonvolatile (contents are not lost when computer is turned off)
- Holds data when the computer is off or during course of a program’s operation
- Serves as archival storage
Random Access Memory (RAM) = Read-write memory
- Type of main memory device
- Volatile
- Data can be read from and written to
- Known as read-write memory
- Direct, find programs easily, open files, running programs
Cache RAM
- Stores recently accessed memory
- Resides on the processor
- Type of RAM (type of main memory)
Read Only Memory (ROM)
- Type of secondary memory
- Nonvolatile
- Data cannot be written to it
- Color computer, programers read first
- Includes Basic Input Output System (BIOS) information and computer system’s clock
- Programmable read only memory (PROM), contents are permanent
- Erasable programmable read-only memory (EPROM), contents can be erased
3 types of Secondary Memory Devices (Hardware)
- Magnetic disks: Used for random-access processing. Data can be accessed in any order
- Magnetic tape: Stores data sequentially, Ex: cassette tape
- Optical disks: Uses laser beams to access and store data, CD’s, DVDs
Cloud storage
- Storage which is used for online storage and backup
- Involves multiple virtual servers that are hosted by 3rd parties
- Customers buy space from 3rd parties depending on needs
Server
Computer and all the software for managing network resources and offering services to a network
Software
- All of the programs that run a computer system
- System software works in the background, takes care of tasks such as deleting waste files Ex: Operating system like Windows
- Application software performs specialized tasks. Ex: Word processing, spreadsheet, database, presentation, graphics
Operating System (OS)
- Set of programs for controlling and managing computer hard and software
- Provides interface between computer and user
- Is an example of system software
- Consists of Control programs (used to manage hardware) and supervisors programs (kernel) used to control all other programs in the operating system (software)
Supervisor program (the kernel)
- Responsible for controlling all other programs in the operating system (OS), i.e. the programs that control programs don’t control
- Known as the kernel
System
- Programers (human) -> System Analyst (human) -> End users (human)
- System has goal (plan goal, look at data) design systems for end users, output
America Standard Code for Information Interchange (ASCII)
- Used for personal computers
- Data code for text files, PC applications, and the Internet
- EBSDIC
- Defines up to 128 characters
Bit
= 2
Binary Digit
Single value of 1 or 0
Byte
= 8 bits
- Used to represent one character (abc, special characters, numbers)
Storage byes order
- Kilobyte (KB): 10^3
- Megabyte (MB): 10^6
- Gigabyte (GB): 10^9
- Terabyte (TB): 10^12
Optical character reader (OCR)
Mechanical or electronic conversion of images of typed, handwritten or printed text into machine-encoded text, whether from a scanned document, or a photo of a document
Magnetic ink character recognition (MICR) system
Used to verify the legitimacy or originality of paper documents
Optical mark recognition (OMR) system
Process of capturing human-marked data from document forms such as surveys and tests.
Classes of computers (4)
- Subnotebooks and notebooks
- Personal and minicomputers
- Mainframes
- Supercomputers
Computer languages
- First Gen: 0s and 1s
- Second gen: Higher level, short codes, mnemonics
- High level: Web, internet
- 4GLS: Macro codes
- 5GLS: Uses artificial intelligence
Redundant Array of Independent Disks (RAID) system
- Collection of disk drives used for fault tolerance and up performance, found in large network
systems/companies - If one disk fails, data isn’t lost, back up storage
Computer does 3 things
- Accepts data as input
- Processes data
- Outputs information
3 factors affecting power of computers
- Seed (millisecond 1/1,000, microsecond 1/1,000,000, nanosecond, picosecond 1/1,000,000,000)
- Accuracy
- Storage (saving data in computer memory) and retrieval capabilities (accessing data from memory)
Input/output devices
Input devices: Send data and information to computers Ex: Mouse, touch screen
Output devices: Capable of representing information from a computer
Ex: Visual, audio, digital, plotters convert output into graphics, voice synthesizers convert output into voice
True or false: Computers can be used in transaction-processing operations that involve enormous values of data
True
Memory stores (3 things)
1) The operating systems and other system software that control or maintain the computer and its devices
2) Application programs that carry out specific task
3) The data being processed by application programs and the resulting information
True or false: Computers and communication systems use data codes to represent and transfer data between computers and network systems
True
CD-ROMs and DVDs are examples of
Optical disks
True or false: A byte is a single value of 0 or 1
False, 1 byte = 8 bits and 1 bit=a single value of 0 or 1
True of false: In the binary number system, 2 is used to represent the value 2
False, the number 2 is used to represent either 0 or 1
