Computer Fundamentals

Visual display terminal most popular input device used today for interactive processing & for the on line entry of data for batch processing.

A video display unit (VDU) consists of: A computer output device that uses a cathode ray tube or other technology to present visual images. One or more input devices, such as a keyboard , a mouse , or both. A synonym sometimes used in the United States is video display terminal ( VDT ).

A video display unit (VDU) consists of: A computer output device that uses a cathode ray tube or other technology to present visual images. One or more input devices, such as a keyboard , a mouse , or both.

GIGO means garbage in garbage out which means if you provide garbage as input the result /output will be garbage only . so if you input incorrect data the output would be not informative and would we incorrect

An IBM System/38 represents the computer class of small-scale computer.

The System/38 was a midrange computer server platform manufactured and sold by the IBM Corporation. The system offered a number of innovative features, and was the brainchild of Frank Soltis and Glenn Henry. IBM announced the System/38 in 1978.

The System/38 was a midrange computer server platform manufactured and sold by the IBM Corporation. The system offered a number of innovative features, and was the brainchild of Frank Soltis and Glenn Henry. IBM announced the System/38 in 1978.[1] Developed under the code-name "Pacific", it was made commercially available in August 1979. The System/38 was oriented toward a multi-user system environment.

Opteron is the name of the 64-bit Microprocessor developed by AMD.

Opteron is family of 64-bit x86 server uniprocessors and multiprocessors designed by AMD as a successor to the Athlon MP family. Opteron processors are designed for workstations and servers and are a direct competition to Intel's Xeon processors.

Opteron is the name of a family of CPUs within the AMD64 line. Designed by AMD for the server market, it competes with Intel's Xeon. For Socket 940 and Socket 939 Opterons, each chip has a three-digit model number, in the form Opteron XYY.

Opteron is AMD's x86 former server and workstation processor line, and was the first processor which supported the AMD64 instruction set architecture (known generically as x86-64). It was released on April 22, 2003, with the SledgeHammer core (K8) and was intended to compete in the server and workstation markets, particularly in the same segment as the Intel Xeon processor. Processors based on the AMD K10 microarchitecture (codenamed Barcelona) were announced on September 10, 2007, featuring a new quad-core configuration.

AMD's main products include microprocessors, motherboard chipsets, embedded processors and graphics processors for servers, workstations and personal computers, and embedded systems applications. AMD is the second-largest supplier and only significant rival to Intel in the market for x86-based microprocessors.

Price on the shelf is not necessary when using bar codes in supermarkets.

It also contains a check digit, so that the computer can validate that the data has been read in correctly. The barcode does not contain price. The price is held in the database instead. This makes it easy to change if there are special offers or prices go up.

The Universal Product Code (UPC) is a barcode symbol that is widely used in the United States, Canada, United Kingdom, Australia, New Zealand, in Europe and other countries for tracking trade items in stores.

A computer will function only if  has a program in its memory.

The chips that make up a computer's internal memory come in two broad flavors known as RAM (random access memory) and ROM (read-only memory). RAM chips remember things only while a computer is powered on, so they're used for storing whatever a computer is working on in the very short term.

Organizing Data Storage. Data is stored as lots of binary numbers, by magnetism, electronics or optics. ... The computer's BIOS contains simple instructions, stored as data in electronic memory, to move data in and out of different storage locations and around the computer for processing.

The proper definition of a modern digital computer is an electronic automated machine that can solve problems involving words and numbers

In computer science, a digital electronic computer is a computer machine which is both an electronic computer and a digital computer. Examples of a digital electronic computers include the IBM PC, the Apple Macintosh as well as modern smartphones.

Advantages commonly attributed to automation include higher production rates and increased productivity, more efficient use of materials, better product quality, improved safety, shorter workweeks for labour, and reduced factory lead times.

A 'number crunching' computer is one that can handle a Large volume of numbers.

a person or thing that performs a great many numerical calculations, as a financial analyst, statistician, computer, or computer program.

The number of bits on a computer hard disk (as of 2010, typically about 1013, 500–1000 GB) The estimated number of atoms in the observable universe (1080) Earth's mass consist of about (4x1051) nucleons. The number of cells in the human body (more than 1014)

The number 2,147,483,647 (or hexadecimal 7FFF,FFFF16) is the maximum positive value for a 32-bit signed binary integer in computing. It is therefore the maximum value for variables declared as integers (e.g., as int ) in many programming languages, and the maximum possible score, money, etc. for many video games.

A googol, for example, is 10^100, which has 101 digits. The largest known prime number has over 17 million digits. A googolplex is 10 raised to the googol power, so it has approximately a googol digits.

EEPROM stands for Electrically Erasable Programmable Read Only Memory. It is a type of non-volatile memory used in computers and other electronic devices.

An IP address consists of 32 bits.

An IP address consists of 32 bits, often shown as 4 octets of numbers from 0-255 represented in decimal form instead of binary form. For example, the IP address: 168.212.226.204 in binary form is 10101000.11010100.11100010.11001100.

Internet Protocol version 4 (IPv4) defines an IP address as a 32-bit number. However, because of the growth of the Internet and the depletion of available IPv4 addresses, a new version of IP (IPv6), using 128 bits for the IP address, was developed in 1995, and standardized in December 1998.

The size of the prefix, in bits, is written after the oblique. This is called “slash notation”. There is a total of 32 bits in IPv4 address space. For example, if a network has the address “192.0.2.0/24”, the number “24” refers to how many bits are contained in the network. It means a single host address. That is called CIDR notation. 192.168.0.1 represents the IP and /32 represents the number of bits in the mask.

In Symmetric key cryptography same secret key is used by the sender and the receiver.

symmetric-key cryptography. An encryption system in which the sender and receiver of a message share a single, common key that is used to encrypt and decrypt the message. Contrast this with public-key cryptology, which utilizes two keys - a public key to encrypt messages and a private key to decrypt them.

Symmetric-key algorithms are algorithms for cryptography that use the same cryptographic keys for both encryption of plaintext and decryption of ciphertext. ... The keys, in practice, represent a shared secret between two or more parties that can be used to maintain a private information link.

The shared secret is either shared beforehand between the communicating parties, in which case it can also be called a pre-shared key, or it is created at the start of the communication session by using a key-agreement protocol, for instance using public-key cryptography such as Diffie-Hellman or using symmetric-key.

Mainframe computers use the 8 bit code called EBCDIC.

Mainframe computers (colloquially referred to as "big iron") are computers used primarily by large organizations for critical applications; bulk data processing, such as census, industry and consumer statistics, enterprise resource planning; and transaction processing.

For separating channels in FDM, it is necessary to use  Bandpass filters

A bandpass filter is an electronic device or circuit that allows signals between two specific frequencies to pass, but that discriminates against signals at other frequencies. Unlike the low pass filter which only pass signals of a low frequency range or the high pass filter which pass signals of a higher frequency range, a Band Pass Filters passes signals within a certain “band” or “spread” of frequencies without distorting the input signal or introducing extra noise.

Frequency Division Multiplexing (FDM) Frequency-Division Multiplexing (FDM) is a scheme in which numerous signals are combined for transmission on a single communications line or channel. It is analog multiplexing technique. ... FDM multiplexing technique is based on orthogonality of sinusoids.

The modulation can be AM,SSB, FM or PM . The modulated signals are then added together to form a composite signal which is transmitted over a single channel . The spectrum of composite FDM signal has been shown in fig.1 . Generally, the FDM systems are used for multiplexing the analog signals .

For separating channels in TDM, it is necessary to use  Time slots.

Time-division multiplexing (TDM) is a method of transmitting and receiving independent signals over a common signal path by means of synchronized switches at each end of the transmission line so that each signal appears on the line only a fraction of time in an alternating pattern.

Time-division multiplexing (TDM) is a method of putting multiple data streams in a single signal by separating the signal into many segments, each having a very short duration. Each individual data stream is reassembled at the receiving end based on the timing.

Time-division multiplexing (TDM) is a method of transmitting and receiving independent signals over a common signal path by means of synchronized switches at each end of the transmission line so that each signal appears on the line only a fraction of time in an alternating pattern. It is used when the bit rate of the transmission medium exceeds that of the signal to be transmitted.

Avalanche effect in encryption is Desirable.

Avalanche effect. ... In cryptography, the avalanche effect is the desirable property of cryptographic algorithms, typically block ciphers and cryptographic hash functions, wherein if an input is changed slightly (for example, flipping a single bit), the output changes significantly (e.g., half the output bits flip).

Avalanche effect, in physics, a sudden increase in the flow of an electrical current through a nonconducting or semiconducting solid when a sufficiently strong electrical force is applied.

Signal becomes weak with increase in distance travelled because of Attenuation.

Consequently, positive attenuation causes signals to become weaker when travelling through the medium. ... Causes of attenuation in both signal frequency and range between the end points of the medium, affect the amount of signal reduction. As the range increases, attenuation also increases.

In a nutshell, attenuation is the loss of transmission signal strength measured in decibels (dB). As attenuation increases, the more distorted and unintelligible the transmission (e.g. a phone call or email you're trying to send) becomes. Inherent attenuation can be caused by a number of signaling issues including:

Transmission medium - All electrical signals transmitted down electrical conductors cause an electromagnetic field around the transmission. ... Crosstalk from adjacent cabling causes attenuation in copper or other conductive metal cabling.

Attenuation is a general term that refers to any reduction in the strength of a signal. ... Sometimes called loss, attenuation is a natural consequence of signal transmission over long distances. The extent of attenuation is usually expressed in units called decibels (dBs).

An information system is defined as a combination of hardware, software, data, procedures, and people that work together to produce information.

The tracks on a disk which can be accessed without repositioning of read write head is Cylinder.

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Cylinders
are vertically formed by tracks. In other words, track 12 on platter 0 plus
track 12 on platter 1 etc. is cylinder 12. The number of cylinders of a disk
drive exactly equals the number of tracks on a single surface in the drive.

So, in order to access a particular cylinder from a track we do not need to
move read write head from that particular track.

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File servers store and manages files for network users.

The function of a computer server is to store, retrieve and send computer files and data to other computers on a network.

The four necessary conditions for deadlock are mutual exclusion, hold and wait (partial assignment), no preemption, and circular wait. Process suspension is not one of these conditions.

Multiprocessor is a computer system Where many CPU under a common control.

Multiprocessing is the use of two or more central processing units (CPUs) within a single computer system. The term also refers to the ability of a system to support more than one processor or the ability to allocate tasks between them. There are many variations on this basic theme, and the definition of multiprocessing can vary with context, mostly as a function of how CPUs are defined (multiple cores on one die, multiple dies in one package, multiple packages in one system unit, etc.).

According to some on-line dictionaries, a multiprocessor is a computer system having two or more processing units (multiple processors) each sharing main memory and peripherals, in order to simultaneously process programs.[3][4] A 2009 textbook defined multiprocessor system similarly, but noting that the processors may share "some or all of the system’s memory and I/O facilities"; it also gave tightly coupled system as a synonymous term.

multiprocessor is a computer system with two or more central processing units (CPUs), with each one sharing the common main memory as well as the peripherals. This helps in simultaneous processing of programs.The key objective of using a multiprocessor is to boost the system’s execution speed, with other objectives being fault tolerance and application matching.

Apple Macintoshes(Macs) and PCs use different CPUs to process data and different operating systems

Macintosh and Windows are two different computer systems, and they run on different operating systems. A Mac computer runs on a Unix-based operating system that is designed and sold by Apple. The operating system being used currently for Macs is Mac OS X, and it is designed around graphic interface. The Windows-based computers operate on different operating systems which are made by Microsoft, and some of these are: Windows XP, Windows Vista and Windows 7. These Windows-based operating systems can be used on a variety of PCs which are widely used.

Macintosh and Windows are two different computer systems, and they run on different operating systems. A Mac computer runs on a Unix-based operating system that is designed and sold by Apple. The operating system being used currently for Macs is Mac OS X, and it is designed around graphic interface.

In functional composition, what is done with data flow diagrams Is ignored and partitioned according to the logical "closeness" of the actigrams.

Flow diagrams in general are usually designed using simple symbols such as a rectangle, an oval or a circle depicting a processes, data stored or an external entity, and arrows are generally used to depict the data flow from one step to another. A DFD usually comprises of four components.

A data flow diagram (DFD) is a graphical representation of the "flow" of data through an information system, modelling its process aspects. A DFD is often used as a preliminary step to create an overview of the system without going into great detail, which can later be elaborated.

A context diagram is a top level (also known as "Level 0") data flow diagram. It only contains one process node ("Process 0") that generalizes the function of the entire system in relationship to external entities. DFD Layers. Draw data flow diagrams can be made in several nested layers.

Word processing is not performed by servers.

Word processors set up and prepare reports, letters, mailing labels, and other materials on a computer using a keyboard and word processing software. Word processors also often perform other clerical duties around an office such as copying documents and answering telephones.

Servers are computers that provide resources to other computers connected to a Network.

A network server is a computer system, which is used as the central repository of data and various programs that are shared by users in a network. If you have a computer that you're no longer using due to its slow speed, you can turn it into a network server for other computers in your household.

In computing, a server is a computer program or a device that provides functionality for other programs or devices, called "clients". This architecture is called the client–server model, and a single overall computation is distributed across multiple processes or devices.

We copy the data to the clipboard temporarily to store it and later can paste it to another location..

At pushdown automata is deterministic if there is at most one transition applicable to each configuration.

In automata theory, a deterministic pushdown automaton (DPDA or DPA) is a variation of the push down automata. The class of deterministic pushdown automata accepts the deterministic context free languages, a proper subset of context free languages.

 A deterministic pushdown automaton has at most one legal transition for the same combination of input symbol, state, and top stack symbol. 

A pushdown automaton (PDA) is a finite state machine which has an additional stack storage. The transitions a machine makes are based not only on the input and current state, but also on the stack.

Mini Computer is smaller size computer but not small as Laptop & Notebook.

The main electronic component used in first generation computers was Vacuum Tubes and Valves.

Vacuum Tubes (1940-1956) The first computer systems used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. Transistors were used for second generation computers and integrated circuits in third generation. First generation computers used vacuum tubes and valves as their main electronic component. Vacuum Tubes were invented by Lee DeForest in 1908.

The first generation computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. • The vacuum tube was developed by Lee De Forest. A vacuum tube is a device generally used to amplify a signal by controlling the movement of electrons in an evacuated space.

Water supply organizations have not become computerized but Banks, railways, Airways have become computerized.

Computerized banking system is a proven, secure, modular, on-line, real-time, flexible, scalable, multi-currency. It is user friendly, easy to manage, and easy to operate information system, based on fully integrated and co-operative components.

A computer reservation system or central reservation system is a computerized system used to store and retrieve information and conduct transactions related to air travel, hotels, car rental, or other activities.