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Software Design & Development
Transcript of Software Design & Development
Cathode Ray Tube (CRT)
Laser printing is the term for an electrostatic digital printing process. Laser printers by passing a laser beam over a charged drum to define a differentially charged image. The drum then selectively collects charged toner and transfers the image to paper, which is then heated to permanently fix the image.
A laser printer needs to receive data and figure out how it's going to put everything on the paper. This is the job of the printer controller.
The printer controller is the laser printer's main onboard computer. It communicates to a computer via a parallel port or USB port. At the start of the printing job, the laser printer will exchange data the host computer.
In an office or school, a laser printer will probably be connected to several separate host computers, so multiple users can print documents from their machine.
Flash Drive is the term for a storage device with an integrated USB (Universal Serial Bus), which plugs into the USB port on a computer, laptop and now days TV's. Flash Drives are removable, re-writable and supersedes the floppy disk, for the amount of data that can be stored on the Flash Drive. the benefits of Flash Drives are that they are smaller, faster, more data capacity and reliable as there are no moving parts.
Operating systems can detect when a flash drive has been connected, and install the necessary drivers by itself. Once the device is finished being used, it needs to be ejected from the computer. The system prompts you when it is safe to remove the flash drive.
A flash drive has a PCB (printed circuit board). It is covered in a plastic or rubber casing to protect the PCB. Once plugged in, a flash drive enters the emulation mode which means it emulates a hard drive thereafter. This makes data transfer between the flash drive and your computer much easier.
A microphone is an instrument for converting sound waves into electrical energy variations which may then be amplified, transmitted, or recorded. Microphones are widely used, for example: In mobile phones, radio broadcasters, stage perfomances, studios, etc.
A microphone is a transducer - a device which converts energy from one form to another. Microphones convert acoustical energy (which is sound waves) into electrical energy (the audio signal).
The diaphragm inside the microphone vibrates as sound waves travel through the microphone. As the diaphragm vibrates, a magnetic coil, which is attached to the diaphragm, converts the vibration into an electrical current which becomes the audio signal.
A barcode reader is an electronic device for reading barcodes. Barcode readers are widely used in shops to read barcodes of products.
Inside the barcode scanner there is a linear photodiode within the scanner head. The photodiode can read the reflected light off the lines on the barcode. The reflection of the light is a digital image that is then scanned electronically. When the image is scanned electronically, each bar on the barcode is converted to the number or letter that is assigned, sent to a computer and (for example-in a shop) matches the number with a product.
The keyboard is the most commonly used computer input device. Keyboards can be wireless or connected to the computer by a cable.
A keyboard is used to enter text information onto a computer. When a key is pressed, the keyboard processor sends a scan code to the keyboard interface circuit on the computer's motherboard. In the past, the code that was sent was the actual ASCII code, (e.g binary codes-lower case 'a'= 1000001 , 'A'= 1100001).
Now days, Modern keyboards sends a more complex code indicating whether a key is pressed or released. The code identifies the position of the key rather than the actual character. The codes that are sent from the keyboard to the keyboard interface on the motherboard via a 6-pin serial port (PS/2). Now days keyboards use a USB port for faster data transfer.
The computer mouse is an essential input device for a computer. The first ever mouse was invented by Douglas Engelbart in 1964 which consisted of a wooden shell, a circuit board and two metal wheels (which came into contact with the surface it was being used on).
In 1972, Bill English developed the "Ball Mouse"'. The ball replaced the wheels and was capable of monitoring movement in any diection. The ball came into contact with two rollers that turned the movement of the ball into electrical pulses representing direction and speed of the cursor on the screen.
An optical mouse, (replacing the "Ball Mouse") has a small, red light-emitting diode (LED), which determines how far the cursor moves when the mouse is in operation, reflecting the red diode from any surface on to a complementary metal-oxide semiconductor (CMOS) sensor. This Sensor sends images to the digital signal processor (DSP) via a USB cable to the computer for analyse. The DSP determines how far the mouse has moved, and the cursor is moved on the screen.
Radio Frequency Identification (RIFD)
Radio Frequency Identification (RFID)
A scanner is the term for a device that optically scans images, printed text, handwriting, or an object, and converts it to a digital image.
A computer communicates with the scanner via a USB cable (for faster data transfer, and USB is commonly used). Scanners usually come with its own software and drivers to help communicate to the computer, but most operating systems, such as Windows, provide a generic device driver that allows most scanners to work. Common scanners work by a light source which is underneath the glass panel, which illuminates the image or document placed on the glass panel. A motor moves the scan head (a series of components that makes up the scan head) underneath the page which captures the reflected light (light is bounced through an intricate system of mirrors, which the light is then focused on a lens). The lens then focuses the beams of light into diodes which translate amount of light into an electric current. this Electric current is then transferred to the computer via a USB cable (or wirelessly now days) to the computer, which displays the digitalised image or document.
A graphics tablet an input device that enables a user to hand-draw images, animations and graphics. The graphics tablet is pretty much a digital page. The tablets can capture the image as data which can be stored as a file or document. The tablet is attached to the computer (via USB), and the stylus can be wireless (most days they are wireless) or connected to the tablet. The tablet reads the drawings made by the stylus and displays them on the computer screen. The drawing does not show up on the tablet, as the tablet is a touch screen, which can be used as a mouse for a computer.
Inkjet printers are the most commonly used type of printer in the house or in schools. An inkjet printer use a series of nozzles to spray small droplets of ink onto paper to create an image or print out a document. Printers communicate with computers via a parallel port or serial port, but now days they use a USB (Universal Serial Bus). When printing out documents there are a number of processes that occur in a short time. As you print a document or image, data is sent to the printer driver, then the driver translates the data into a format that the printer can understand. Once the paper is fed into the printer and positioned at the start of the page, the print head stepper motor uses the belt to move the print head assembly across the page. The motor pauses for the merest fraction of a second each time that the print head sprays dots of ink on the page, then moving a tiny bit more before stopping again.
LCD (or Liquid Crystal Display) is used in computer monitors, TV's and many more devices. LCD technology works by blocking light. LCD display is made of two pieces of polarized glass that contain a liquid crystal material between them. A backlight creates light that passes through the first piece of glass. At the same time, electrical currents cause the liquid crystal molecules to align to allow varying levels of light to pass through the second piece of glass and creates an image on the screen
Plasma display is an element that displays text or graphics using the light from plasma, which iss generated during gas discharging. Plasma display consists of two (transparent) glass panels with a thin layer of pixels sandwiched in between. Each pixel is composed of three gas-filled cells or sub-pixels (red, green and blue). A grid of tiny electrodes applies an electric current to the individual cells, causing the neon and xenon gas in the cells to ionize. This ionized gas (plasma) emits high-frequency UV rays, which stimulate the cells' phosphors, to glow the desired colour.
Speakers are commonly used in a variety of areas: for example - speakers are used in TV's, computers, cars, radios, etc. Speakers receives electronics signals via a 3.5mm jack or wirelessly (bluetooth), and converts it into sound.
A speaker receives the electrical signal from a device (e.g. a computer, IPod, etc) and translates it back into physical vibrations to create sound waves.
The signal from a device constantly reverses the flow of electricity. The voice coil is an electromagnet. Since electrons always flow in the same direction, the current going through the speaker moves one way and then reverses and flows the other way. This alternating current causes the polar orientation of the electromagnet to reverse itself many times a second, which causes this vibrations. Speakers with a power supply enhances the sound quality by adding more power through the electrical signal recieved by the speaker.
A data projector is an image projector that receives a signal from a data source (e.g. a computer) and projects the image on a wall or projection screen. Data projectors are common in school classrooms, often in conjunction with an interactive whiteboard. There are two main types of Data Projectors: LCD (Liquid Crystal Display, see LCD display for more information on LCD) and DLP (Digital Light Processing).
The digital signal is sent from a computer via a VGA () cable to the data projector. As the Data projector receives this signal, it converts it to a light beam. To the right, the images show how LCD and DLP projectors project images.
A DVD burner, AKA a DVD writer, is a hardware equipment that works with a computer to store and copy data to a DVD.
To write/burn data onto a blank DVD, which can be read by a DVD player, the DVD burner has to record a digital arrangement of reflective and non-reflective portions. A moving write laser beam has to make alterations to the disc's surface. The write laser beam follows the same spiral pattern which the read laser beam of a DVD player. While the disc is spinning, special technology calibrates the rate the disc is spinning with the laser beam's speed. The beam's rate should be consistent for accurate burning. To produce the 1s and 0s, the DVD writer turns the beam on and off. The beam is turned on to make the dye dark, which represents the 0s or the protuberances. The beam is turned off for the purpose of encoding the 1s or flat portions. DVD burners are not usable unless the correct software is available. Can be purchased or downloaded from the internet.
CD burners (CD writers) are included in computers these days (CD drive). This technology allows data such as music to be stored on Compact Discs (CD's) (see storage devices-CD). The purpose of the CD burner is to "burn" the data as a digital pattern onto a blank CD. The CD burner has a moving laser assembly, just like an ordinary CD player, although in addition to the standard "read laser," the burner has a "write laser", which is more powerful than the "read laser". The "write laser" moves in the same way as the "read laser", moving outwards from the center of the disc, as the disc is spinning. The calibration of the rate the disc is spinning keeps the laser running a constant speed, which gives accurate burning when in progress. To record the data on the CD, the burner simply fluctuates the "writer laser" on and off, in sync with the pattern of 1s and 0s.
A Hard Drive can be inside a computer or an external storage device, both though work the same. A hard drive in a computer is one of the most important hardware device as it's job is to store the computers data.
A hard drive is a storage device that rapidly records and reads data represented by a collection of magnetized particles on spinning platters. As you are looking for data, the computer sends the message to the controller once data is needed. The controller checks its registry for the location of the data. Once the data is found, the controller moves the appropriate heads to the place they need to be. The controller then uses the actuator arm to read the data off the magnetic platters that are attached to the heads. the computer communicates to the hard drive via a SATA port from the Mother board.
Compact disc (CD) is a digital optical disc data storage format. CD's are used to hold music, data or computer software. A CD has a single spiral track of data, circling from the center of the disc working towards to the edge of the CD. The CD is rotated by a drive system that regulates the speed of rotation so that data is read at the same speed regardless of the laser detector's position.
Light from the laser beam must pass through a thin protective layer of plastic on the CD before striking the reflective coating that contains pits and landings. As the disc rotates, light reflected from landings on the disk strikes the photo sensor producing a series of electrical pulses that are coordinated with a timing circuit to generate a stream of 1s and 0s that produce the binary code of information on the disc. For more information about CD's look at CD writers/Burners.
The laser beam shines through the surface of the disc then reaches the metal surface. It will either hit a bump or no bump from the recording dye. The Recording dye is what holds information as a binary code as 0s and 1s. See how data is stored on CD's (look at CD writers/burners).
DVD ('Digital Versatile Disc' or 'Digital Video Disc') is a digital optical disc storage format, supersedes the amount of data held on CD's. Like a CD, data on a DVD is encoded in the form of small pits and bumps in the track of the disc. As shown in the picture to the right, the pits on a DVD is much smaller than the pits on a CD, which results to more data capacity. DVDs are mainly used for video use due to the amount of data being able to store on a DVD. Blu-ray Discs are even better than DVDs because of more data being able to fit on the same size disc using a blue laser diode. In order to fit a movie on a DVD, you need video compression. Because of DVD compression techniques, DVDs can hold more data than CD's and other older formats. The process of burning data on DVDs are similar to CDs
Processing devices in a computer are responsible for controlling the storage and retrieval of information. The information is processed by the computer processor unit (CPU), performs data calculations, data comparisons, and data copying with the information from the processing devices. The CPU then saves that information to the computer memory (RAM). Computers now days contain multiple processing devices. Any device that deals with the input and output of information does some form of processing on that information, some with more complexity than others. The one processing device that most people think of is the CPU, but devices like the graphics card, computer memory, network card, and others are processing devices as well.
HARDWARE AND SOFTWARE
By: Evan Koltsis
High Level Languages
Source code is a collection of statements written in a high-level language. The CPU can not make sense of these statements, and they must be translated into machine language. There are main methods for the process of translation: compilation and interpretation. The process of compilation involves translating the entire source code into object code. The object code is then combined with other linked files to create the final executable files. These executable files can then be executed repeatedly at a later time without the services of the compiler. Compiled code executes fast as there is no translation required at run time. Virtually all applications we use on computers have been compiled.
When using a compiled application it is difficult to determine the original high-level language used for its development. The compiled code is a series of machine language instruction. This provides protection for the software developer as it is very difficult to alter the code. Similarly, determining the nature of the original source code is very difficult to achieve from executable machine code.
Another method of translation is Interpretation. Interpreters translate source code statement by statement. After each statement has been translated into machine code it is immediately executed. This process of translation then execution continues until either an error in a line of source code is encountered or the application ends. The process of translating code at run time is a significant processing overhead resulting in poor performance. Few applications are executed by user using interpreters; rather interpreters are used by programmers to test their code as it is being developed. When running programs using an interpreter you must have a copy of the interpreter installed together with the original source code. To distribute a program in this way makes copying and alteration of the source code simple. For commercial software this is a definite problem. Some declarative language do not use compilers, rather they must be interpreted. In these cases,the interpreter is one use compilers, rather they must be interpreted. In these cases,the interpreter is one part of the programming environment. The environment provides most of the processing support for the application.
Assembly languages were the first attempt to make programming language more human like. These languages use mnemonics to represent different commands available in the assembly language. A mnemonics is simply an aid to assist in remembering, For example, "add ax" means add to accumulator and is far easier to remember than 10100001. Programs written in an assembly language cannot be understood by the CPU. An assembler is required to translate the assembly code into machine language. The translation process is straightforward as the majority of the commands translate directly into single machine language instructions. Programs written in assembler can be optimised for particular processors. As a consequence assembly language programs are often written for routines where speed is crucial e.g. graphics intensive operations. The resulting machine language is then combined with the code generated from other higher-level languages.
High Level Languages
High-Level languages are designed to simplify the programming process. They allow programmers to concentrate on solving problems rather than dealing with the mundane details of the hardware systems. There are many hundreds of different high-level language available today, each with it's own particular strengths and weaknesses. For example, Fortran is used for scientific applications, Cobol for business applications, prolog for artificial intelligence applications and pascal teaching applications.
All high-level language must be translated into machine code using a translator. Different translators are available for different models of CPU. This allows high-level code (source code) to be translated into the machine language (object code) appropriate to a particular CPU. We examine different methods of translation later in this chapter. The high-level code is said to be machine independent. program code could now be reused on different machines with little modification.
High-Level language use commands that are more readily understood by humans. they are designed for the use of human programmers. For example, the command write"hello" has a clear English meaning compared to the equivalent set of machine language instructions that are actually executed by the CPU. This makes the task of programming more intuitive and greatly assists the maintenance of existing code.
The majority of high-level language in common use today require the programmer to unambiguously describe how a problem is to be solved , these language are known as third generation language. In the next section we consider declarative languages where the emphasis is on what needs to be done rather than how it is to be accomplished.
Many high-level language have maintained a steady following since their initial creation, e.g. Lisp, whilst themselves being specialised and not widely known. describes the historical development of most of the commonly used language; there are hundreds of other language not included on the above timeline.
The CPU is able to execute a limited number of inbuilt of inbuilt commands .These commands are called the instruction set for the processor. A machine language program is a collection of these commands. Each machine language instruction is represented by the computer as a series of binary digits e.g 10011101010011010011. To the casual human observer it is impossible to make any sense of machine language in its native form. Nevertheless every program ever written is ultimately converted into a series of machine language instructions. They have to be; these instructions are all the computer can actually understand.
Prior to the development of the keyboard machine language instructions were entered using a series of cables that effectively opened and closed particular circuits. Later punched cards were introduced. These cards provided a storage medium allowing programs to be reloaded more easily. Once the keyboard arrived machine language was entered in hexadecimal, this reduced the volume of data entry significantly. In hexadecimal every 4 bits 9binary digits) can be represented using a single character.
Each machine language instruction contains two parts, an operation code (opcode) and one or more operands. The majority of instructions require a single operand. the opcode identifies to the control unit what process is to be performed and the operand provides the data on which the process is to be performed. For example, on a pentium machine the instruction 10100001 00000000 00000010 adds the decimal number 2 to the value currently in the accumulator. 10100001 is the opcode letting the control unit know to carry out an add to the accumulator and 00000000 00000010 is the decimal value 2 using 16 bit binary. For many operations the operand will be a memory address rather than the data itself.
Traditional or imperative language have developed as a consequence of the design of the hardware. They require programmers to describe the sequence of processes leading to the solution of the problem. you must know precisely how to solve the problem before you can hope to write a program. declarative are very different, instead programs are more a formal description or specification of a problem. In most cases the order of statements is of little or no significance. Code written in a declarative language describes what the problem is rather than how it can be solved. The program works out a method of solution as it executes. Examples of Declarative languages include Prolog, Lisp, APL and Haskell. Nearly all Declarative languages are used for specialised tasks involving artificial intelligence.
The operating system is the most important program that runs on a computer. The operating system manages the hardware, the user interface and all other software running on the computer. Without an operating system, a computer is just a collection of components, which no-one would be able to make any practical use of the computer. Every general-purpose computer must have an operating system to run other programs. Operating systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as disk drives and printers.
For large systems, the operating system has even greater responsibilities and powers. The operating system makes sure that different programs and users running at the same time do not interfere with each other. The operating system is also responsible for security, ensuring that unauthorized users do not access the system.
Software instructions processed by the CPU are always in machine language. This is all the CPU, or more precisely the control unit, can understand. The method of executing each machine language statement is hardwired within the CPU. Each machine language instruction corresponds to a precise series of operations from the CPU. These CPU operations are known as microcode.
The fetch-execute cycle is used to carry out each and every machine language instruction. This cycle can be split into instruction time (I-time) and execution time (E-time). Instruction time involves fetching the instruction from memory and decoding it. Execution time involves executing the instruction and storing the result. The fetch-execute cycle occurs at a constant pace. The system clock determines this pace. At each tick of the clock a part of the fetch-execute cycle occurs.
A register is a temporary but very fast storage area within the CPU. There are a number of registers crucial to the operation of the fetch-execute cycle. The program counter holds the address of the next instruction to be executed. It is a counter because in most cases, instructions are held sequentially, thus the program counter is incremented to point to the address of the next instruction. The instruction register holds the machine language instruction waiting to be executed. The accumulator together with other general-purpose registers, are used to store data and any results during and after processing.
Below are the steps involved in the fetch-execute cylce:
* Fetch-the instruction at the address in memory indicated by the program counter,is read into the instruction register. The program counter is then incremented to point to the next instruction.
*Decode-the control unit makes sense of the instruction. It then directs other components to load any required operands into the appropriate registers.
*Execute-the instruction is actually carried out. For most instructions,the services of the ALU are used.
*Store-the results are stored in one or more of the general-purpose registers. A further instruction is needed to move the result to RAM.
Modern CPU's are able to process multiple concurrently. While one instruction is being fetched, another is being decoded and another is being executed. This is called pipelining. Most CPUs have more than one ALU, which means instructions that do not affect one another can be executed at the same time. These and other techniques significantly improve the performance of modern CPUs.
Cathode Ray Tube
Cathode Ray Tubes (CRT) were used in a variety of devices such as old TV's, computer monitors etc. A cathode ray tube is a specialized vacuum tube in which images are produced when an electron beam strikes a phosphorescent surface, (thats why they are so big and heavy). CRT's consist of one or more electron guns (a source of electrons or an electron emitter) (usually 3 guns: red, blue and green) and a fluorescent screen used to view images. It shoots an electron beam onto the screen to create the images.CRTs have been superseded by newer display technologies such as LCD and plasma display, which have lower manufacturing costs, power consumption, and weight.
Radio-frequency identification (RFID) is the wireless non-contact use of radio-frequency electromagnetic fields to transfer data, for the purposes of automatically identifying and tracking tags attached to objects. The tags contain electronically stored information. Some tags are powered by and read at short ranges (a few meters) via magnetic fields (electromagnetic induction). Others use a local power source such as a battery, or else have no battery but collect energy from the interrogating EM field, and then act as a passive transponder to emit microwaves or UHF radio waves (i.e., electromagnetic radiation at high frequencies). Battery powered tags may operate at hundreds of meters. Unlike a barcode, the tag does not necessarily need to be within line of sight of the reader, and may be embedded in the tracked object.
Radio frequency identification (RFID) is part of the family of Automatic Identification and Data Capture (AIDC) technologies that includes 1D and 2D bar codes. RFID uses an electronic chip, usually applied to a substrate to form a label, that is affixed to a product, case, pallet or other package. The information it contains may be read, recorded, or rewritten
Discuss the impact of using particular devices on the development and use of software
Overtime, the use of computers and hand held have increasingly become popular. Software must be created to work with these devices. Mobile Phones is one of the most popular devices around, in which software must be created and installed in these devices. The size of mobile phones is a big restriction to what can be inside the phone for example: a hard drive cannot fit in a mobile phone so there has to be another way for the availability of storage. In phones an App can be downloaded on to a phone via the internet in which software is available to the public. Software was once available for computers when they first came out, and now software is download-able for phones, ipods, tablets etc.
Discuss the current trends in the development of software and operating systems
Software development is the computer programming, documenting, and testing involved in creating and maintaining applications and frameworks involved in a software release life cycle and resulting in a software product. The term refers to a process of writing and maintaining the source code, some of the most current trends include prezi which is internet based and power point is on computers another one is an app apps are stored on hard drives on tablets they have a smaller hard drive which is small and capable of running on tablets with small memory. they don't do as much as computer software.
For desktop systems, access to a LAN or the Internet has become such an expected feature that in many ways it's hard to discuss an operating system without making reference to its connections to other computers and servers. Operating system developers have made the Internet the standard method for delivering crucial operating system updates and bug fixes. a process called NetBooting has streamlined the capability to move the working operating system of a standard consumer desktop computer.
Discuss the current trends and developments in computer hardware
Discuss the current trends and development in computer hardware?
Computers in the foreseeable future trends: is toward smaller, faster computing operating system work more stable direction, the future of computer programs can achieve more parallelism, high overclocking operation, high-quality, low-calorie, high read and write speed, large storage capacity, compatible with the goal of playing style.
For example, Trend 1: more compact Hardware development is in constant pursuit of more compact. Advantage of volume on so you can easily bring them to any place, and then later, they can even be reduced to the built-in your clothes or skin. The key to achieve this dream is to produce faster, smaller, cheaper computer chips. The use of nanotechnology can make these appliances and digital products more intelligent, more features; hand, handheld data processing computing performance will be greatly improved, and truly become easy to carry "pocket computer."
Trend 2: cheaper, IT experts emperor in Tunis released $ 100 laptop prototype, this emerald green computer is for millions of children in poor countries and design. This "spring-type notebook" power consumption is very low. $ 100 computer design is: 500MHz processor, 1GB of memory and an innovative dual-mode display - both full-colour display mode, there are sunlight readable monochrome display mode. Nigeria's say, a computer monitor so that looks like the book, and like computers. The notebook's power available external power supply, battery, or connect the computer's own power generation winding crank, because many countries in remote areas without electricity.
The keyboard is no longer the only tool used to typing, he has also been given to play the game, play a variety of video and other new missions. In order to accomplish these missions, the keyboard is no longer only contain letters or numbers keys, many products have additional multimedia keys, game dedicated function keys, and some special products even still incorporates a touch screen keyboard. For example, Optimus Maximus is a fully customizable keyboard, you can freely adjust the keys and the keys on the keyboard letters to define each key, and each key bits with independent display function on the keycaps can show the key features possessed icon, Optimus Maximus, a total of 113 48x48 screen resolution keycaps. Logitech G19 gaming keyboard called the most sophisticated, the keyboard has two high-speed USB2.0 ports, multi-key input feature allows the keyboard to allow five keys are pressed simultaneously, in order to meet the needs of complex actions in the game. The keyboard also has a 320x240 resolution colour LCD display, can display the data game / system and so on. In addition, this keyboard also has a backlight design
With the development of technology, more and more integrated hardware and software, electronic products increasingly integrated, the product is to be pursued overall utility, rather than merely functional