1 What is a Computer?
The definition of a computer varies from one piece of literature to another. Dictionary.com provides two definitions:
Also called processor. an electronic device designed to accept data, perform prescribed mathematical and logical operations at high speed, and display the results of these operations.
a person who computes; computist.
The first definition has changed slightly since the original version of this overview. As of June 2017, dictionary.com defines a computer as:
- a programmable electronic device designed to accept data, perform prescribed mathematical and logical operations at high speed, and display the results of these operations. Mainframes, desktop and laptop computers, tablets, and smartphones are some of the different types of computers.
Compare analog computer, digital computer.
The American Heritage® Science Dictionary defines a computer in a more “modern” context:
A programmable machine that performs high-speed processing of numbers, as well as of text, graphics, symbols, and sound. All computers contain a central processing unit that interprets and executes instructions; input devices, such as a keyboard and a mouse, through which data and commands enter the computer; memory that enables the computer to store programs and data; and output devices, such as printers and display screens, that show the results after the computer has processed data.
While this is correct, the updated 2017 Dictionary.com definition describes computers from a more abstract (i.e., high-level) view.
This high-level (i.e., abstract) view is important in the context of modern computing devices:
Smartphones and tablets generally rely on touchscreens for user input.
Videogame consoles rely heavily on controller input (i.e., joysticks and buttons).
Many of these devices include functionality for audio-based (Siri on the Apple iPhone), or motion-based (the Nintendo Wii Remote or Xbox Kinect) input.
2 Moving Forward
The size of the processing unit has dramatically reduced since the introduction of the first machine meeting the definition of a computer. In addition, the speed with which the processor can complete the programs it is tasked with running has dramatically increased. And finally, the associated memory, or associated storage, has seen dramatic increases in capacity, along with even more impressive reductions in size and function.
Keep these changes in mind when reading the content of this module on The History of Computers.
History of Computers – a timeline of the evolution of the computers as a whole, including reduced size, improved functionality, and increased complexity.
History of Computer Memory – a timeline of evolution of portable memory devices, including reduced size, increased storage capacity.
History of Mobile Computing – a timeline of portable computing devices
What is a computer ?
In its most basic form a computer is any device which aids humans in performing various kinds of computations or calculations. In that respect the earliest computer was the abacus, used to perform basic arithmetic operations.
It is a Device, (mechanical or Electronic or Elctro-Mechanical) that manipulates data (mechanically, or electrically ) to achieve some desired output(s). Ex, Clocks/Watches (computes the time), calculators (compute numbers), slide-rule (engineering computation), Turing machine, Difference Machine, Analytucal Machine, Type Writer (Word Processor), Enigma (German Encryption Machine), Eniac(The first programmable general-purpose electronic digital computer,), IBM-360, Sun Sparcs/Ultras, Apple Mac, Ipad, Iphones, BlackBerry, etc.
A Brief History of Computing.
How do you define a modern day computer ?
Computer is a Digital Electronic Device capable of Accepting Data or retrieving information (Inputing Data/Gathering or Collecting Information), manipulates or process these data (Processor) by Arithmetic or Logic Operations (ALU)
using sets of Instructions (Programs) to record (Storage) or produce (Output) the desired results.
From our definition of a computer, we can list down the Basic parts required to process a data.
- Input Device - Inputing Data/Gathering or collecting Data
- Processor Device - manipulates or process the data
- Arithmetic and Logic Device - Arithmetic or Logic Operations
- Memory Device – Store/Process Program/Data
- Storage Device - Store/Process Program/Data
- Output Device – Output the desired results.
There are two basic major components of any computer system.
I - Hardware Components – All the Physical parts of the computer. (KB, mouse, monitor, CPU, Memory, Hard Disk, CD-Drive, MBU, etc) .
II - Software Components – Programs that operate on or manipulate Data and Hardware components. They can be classified into 2 types: 1) System Softwares (OS or Operating System) and
2) Application Softwares (Driver Programs, Application Programs)
Examples of
System Softwares – Windows NT/XP/7/8. MAC, RedHat, Debian, Ubuntu, Centos, Symbian, Android, VMware, Hyper-V, etc.
Examples of Application Softwares – Excel, Word, PowerPoint, SQL, Apache, PHP. Perl, Java, C++, Internet Browser, Media Player, Anti-Virus, etc
Examples of Drivers – Print Drivers, USB Drivers, CD/DVD Drivers, NIC Drivers,
etc.
LOGICAL UNITS of a COMPUTER
Regardless of differences in physical appearance, virtually every computer may be envisioned as divided into six logical units or sections:
1. Input unit. This is the "receiving" section of the computer. It obtains information (data and computer programs) from input devices and places this information in memory at the disposal of the other units for processing. Most information is entered into computers through keyboards and mouse devices. These Information or Data Items also can be entered in many other ways, including by speaking to your computer (sounds), scanning images and having your computer receive information from a mouse or a network, such as the Internet.
2. Output unit. This is the "shipping" section of the computer. It takes information that the computer has processed and places it on various output devices to make the information available for use outside the computer. Most information output from computers today is displayed on screens, printed on paper or used to control other devices. Computers also can output their information to networks, such as the Internet.
3. Memory unit. This is the rapid-access, relatively low-capacity "warehouse" section of the computer. It stores computer programs while they are being executed. It retains information that has been entered through the input unit, so that it will be immediately available for processing when needed. The memory unit also retains processed information until it can be placed on output devices by the output unit. The memory unit is often called as memory or primary memory or RAM. Random access memory, or RAM, is a form of internal, volatile memory. Programs that are currently running and data items that are currently being used are stored in RAM for quick access. Internal storage is volatile—its contents are lost when the computer is turned off or loses power.
4. Arithmetic and logic unit (ALU). This is the "manufacturing" section of the computer. It is responsible for performing calculations, such as addition, subtraction, multiplication and division. It contains the decision mechanisms that allow the computer, for example, to compare two items from the memory unit to determine whether they are equal.
5. Central processing unit (CPU). This is the "administrative" section of the computer. It coordinates and supervises the operation of the other sections. The CPU tells the input unit when information should be read into the memory unit, tells the ALU when information from the memory unit should be used in calculations and tells the output unit when to send information from the memory unit to certain output devices. Many of today's computers have multiple CPUs and, hence, can perform many operations simultaneously such computers are called multiprocessors.
6. Secondary storage unit. This is the long-term, high-capacity "warehousing" section of the computer. Programs or data not actively being used by the other units normally are placed on secondary storage devices, such as your hard drive, until they are again needed, possibly hours, days, months or even years later. Information in secondary storage takes much longer to access than information in primary memory, but the cost per unit of secondary storage is much less than that of primary memory. Secondary storage are Permanent storage devices and are nonvolatile—that is, their contents are persistent and are retained even when power is lost. Other secondary storage devices include CDs and DVDs, which can hold hundreds of millions or billions bytes of data (MegaBytes, GigaBytes), respectively.
MAJOR COMPUTER OPERATIONS
We can actually group these Logical Units into 4 Functional Units of Operations which are regarded as the major computer operations accomplish tin ogether by the hardware and software components of a computer system.
- Input Unit – Input functions
- Process Unit = CPU + ALU) – Computing Functions
- Output Unit – Output Functions
- Storage Unit (Memory / Storage devices) – Storage Functions
We can combine the Storage Unit with the Process Unit and Output Unit. This way we have 3 major computer operations in computer programs.
Input --> Processing --> Output
Input—Data items enter the computer system and are placed in memory, where they can be
processed. Hardware devices that perform input operations include keyboards and
mice. Data items include all the text, numbers, and other raw material that are entered
into and processed by a computer. In business, many of the data items used are facts and
figures about such entities as products, customers, and personnel. However, data can also
include items such as images, sounds, and a
user’s mouse movements.
Processing—Processing data items may involve organizing or sorting them, checking
them for accuracy, or performing calculations with them. The hardware component that
performs these types of tasks is the central processing unit, or CPU.
Output—After data items have been processed, the resulting information usually is sent to a printer, monitor, or some other output device so people can view, interpret, and use the results. Programming professionals often use the term data for input items, but use the term information for data that has been processed and output. Sometimes you place output on storage devices, such as disks or flash media. People cannot read data directly from these storage devices, but the devices hold information for later retrieval. When you
send output to a storage device, sometimes it is used later as input for another program.
The Language of a Computer
The most basic language of a computer is the machine language which
provides program instructions in bits (binary digits). Because digital signals are processed inside a computer, the language of a computer, called machine language, is a sequence of 0s and 1s. Bit stands for a binary digit of 0 and 1 and bits is a sequence of 0s and 1s and is referred to as a binary code or a binary
number. A sequence of eight bits is called a byte. Moreover, 210 bytes = 1024 bytes is called a kilobyte (KB).
Table below summarizes the terms used to describe various numbers of bytes.
Every letter, number, or special symbol (such as * or {) on your keyboard is encoded as a
sequence of bits, each having a unique representation. The most commonly
used
encoding scheme on personal computers is the seven-bit American Standard Code
for Information Interchange (ASCII). The ASCII data set consists of 128 characters numbered 0 through 127.
The numbers 0-12 in the first column specify the left digit(s), and the numbers 0-9 in the
second row specify the right digit of each character in the ASCII data set. For example, the character in the row marked 6
(the number in the first column) and the column
marked 5 (the number in the second row) is A. Therefore, the character at position 65
(which is the 66th character) is A.
ASCII is a seven-bit code. Therefore, to represent each ASCII character inside the
computer, you must convert the seven-bit binary representation of an ASCII
character
to an eight-bit binary representation. This is accomplished by adding 0 to the left of the
seven-bit ASCII encoding of a character. Hence, inside the computer, the character
A is represented as 01000001, and the character 3 is represented as 00110011.
There are other encoding schemes, such as EBCDIC (used by IBM) and Unicode,
which is a more recent development.
EBCDIC consists of 256 characters; Unicode
consists of 65,536 characters. To store a character belonging to Unicode, you need
two bytes.
Unicode Table //www.grogllc.com/unicodetable.html