Computer
A machine that accepts data as input, processes data without human intervention using stored instruction, and outputs information
Source Code (Program)
Must be translated into object code consisting of binary 0s and 1s (input to the complier)
Object Code
Created by complier, binary digits (output of the compiler)
Garbage in, garbage out (GIGO)
If input data is erroneous, the information provided by the computer is also erroneous
Hardware components
physical devices (keyboards, monitors, and processing units)
Software Components
Programs written in computer languages
Computer performs three basic tasks
arithmetic operations, logical operation, & storage and retrival operations
Central Processing Units (CPU)
Computers can either have a single processor or multiprocessors
Bus
link between devices connected to the computer
Disk drive
peripheral device for recording, storing, and retrieving information
CPU case
enclosure containing the computer’s main components
Motherboard
main circuit board containing connectors for attaching additional boards
speed, accuracy, storage, and retrieval capabilities
Computer draw their power from 3 factors
Speed
rate at which a computer performs instructions
Millisecond
1/1,000 of a second
Microsecond
1/1,000,000 of a second
Nanosecond
1/1,000,000,000 of a second
Picosecond
1/1,000,000,000,000 of a second
Accuracy
computer’s usage of values close to the true values, degree of accuracy is critical in many computer applications
Storage
saving data in a computer memory
retrieval
accessing data from memory
Bits
what data is stored in
American Standard code for information interchange (ASCII)
data code for text files, PC applications, and the internet
1 bit
a single value of 0 or 1
8 bits
1 byte or character
Input, Output, Memory
To use a computer and process data, three major components are needed
Input Devices
Send data and information to the computer (keyboard, mouse, barcode reader, etc.)
Output Devices
Receive and displays the results from the computer (head phones, printer, speakers, etc.)
Main memory
stores data and information, directly accessed by the CPU, usually volatile
Secondary memory
stores data and information, nonvolatile, serves as archival storage
Random Access Memory (RAM)
Volatile memory, in which data can be read from and written to (Cache RAM - stores. recently accessed memory)
Read-only (ROM)
nonvolatile, data can be read but cannot be written to the memory, typically stores BIOS information, and the computer system’s clock
Cloud Storage
Online storage and backup of data, commonly involves multiple virtual servers, usually hosted by third parties, customers usually buy or lease storage space based on needs
Storage Area Network (SAN)
dedicated high-speed network consisting of both hardware and software
Network-attached storage (NAS)
Network-connected computer dedicated to provide file-based data storage services to other network devices
Server
computer and all the software for managing network resources and offering services to a network
Software
the programs that run a computer system
System Software
Programs for operating the hardware components and the application software (what you want the computer to do) (Microsoft Windows)
Application Software
Programs employed by end users to perform specific tasks (use to run the machine) (Microsoft Excel and Microsoft Access)
Operating System Software
Set of programs for controlling and managing computer hardware and software
Supervisor Program
Responsible for controlling all other programs in the OS
Kernal
Program at the core of an operating system, connects the application software to the hardware components, controls everything that occurs in the system
Application Software
Commercial software or software developed in house; used to perform a variety of tasks on a personal computer (zoom, google docs, etc.
Machine Language
first generation of computer languages, consists of a series of 0s and 1s representing data or instructions
Assembly Language
Second generation of computer languages, higher-level language than machine language
High-level languages
third-generation of computer languages
Fourth-generation Languages (4GLs)
Uses macro codes replacing several lines of programming, commands are powerful and easy to learn
Fifth-generation Languages (5GLs)
use artificial intelligence technologies, designed to facilitate natural conversations between an individual and the computer (siri, google)
Database
collection of related data that is stored in a central location or in multiple locations
Data Hierarchy
Structure and organization of data, which involves fields, records, and files
Database Management System (DBMS)
Software for creating, strong, maintaining, and accessing database files
Internal Data
Collected from within an organization, stored in the organizations internal database
External Data
Comes from a variety of sources, stored in a data warehouse
Sequential access file structure
records in files are organized and processed in numerical or sequential order, organized based on a primary key, used for backup and archive files
Random access file structure
Records can be accessed in any order, regardless of their physical locations in storage media, (data is small)
Indexed sequential access method (ISAM)
Records accessed sequentially or randomly, depending on the number accessed
Physical View
How data is stored on and retrieved from storage media
Logical View
How information appears to users and how it can be organized and retrieved
Data Structure
describes how data is organized and related
operations
describe methods and calculations performed on data
Integrity rules
define the boundaries of the database
Hierarchical Model
Relationships between records from a treelike structure
Network Model
Similar to the hierarchical model but records are organized differently
Relational Databases
Stores data in the form of relations
Attribute
the properties that define a relation
Relation Schema
represents the relation’s name with its attributes
Tuple
Each row in the relation is known
Relation Instance
The set of tuples of a relation at a particular time
Degree
The number of attributes in the relation is known as the degree of the relation
Cardinality
The number of unique values in a relational table
NULL Values
The value that is unknown or unavailable
Data dictionary
Stores definitions, such as data types for fields, default values, and validation rules for data in each field (first step)
Super Key
is a set of one or more attributes that are taken collectively and can identify all other attributes uniquely
Candidate Key
The minimal set of attributes that can uniquely identify a tuple (the minimum combination)
Primary Key
There can be more than one candidate key in relation, out of which one can be chosen as the primary key.
Foreign Key
If an attribute can only take the values which are present as values of some other attribute
Normalization
Process of structuring a relational database with standard normal forms
Operations
Relational DBMS retrieves data from tables using operations that pick and combine data from one or more table
Database Engine
Responsible for data storage, manipulation, and retrieval (the heart of the data base)
Data Definition
Used to create and maintain the data dictionary (what is inside the data)
Data Manipulation
Used to add, delete, modify, and retrieve records from a database
Application Generation
designs elements of an application using a database
Data Administration
Used for tasks such as backup and recovery, security, and change management
Database Administrators
Handle database design and management
Data-driven Web sites
Retrieve data and allows users to enter data in the database, improve access to information
Distributed Database Management System (DDBMS)
Stores data on multiple servers throughout an organization
Fragmentation
addresses how tables are divided among multiple locations
Replication
each site stores a copy of the data in the organization’s database
Allocation
combines fragmentation and replication
Object-Oriented Databases
Data and their relationships are contained in a single object
Encapsulation
grouping objects along with their attributes and methods into a class
Inheritance
new objects can be created faster and more easily by entering new data in attributes
Data Warehouse
Collection of data from a variety of sources
Raw Data
Data in its original form
Summary Data
Data on the subtotals of various categories
Metadata
Data about the data (data’s content, quality, condition, origin, and other characteristics)
Online Transaction Processing (OLTP)
Used by transaction-oriented application, used to analyze transaction-oriented data
Online Analytical Processing (OLAP)
Used to generate business intelligence, uses to analyze data from multiple sources, involves multidimensional analysis
Data-mining analysis
Involves examining the data to discover patterns and relationships
Decision-making reports
Involves creating reports used for decision-making