It forms images from tiny dots, called pixels that are arranged in a rectangular form. The sharpness of the image depends upon the number of pixels. It is a device used to move cursor position on a monitor screen.
A scanner allows you to scan printed material and convert it into a file format that may be used within the PC. A plotter is used to create high-quality visuals on paper.
Plotters were used in applications such as computer-aided design, though they have generally been replaced with wide-format conventional printers.
A plotter gives a hard copy of the output. It draws pictures on a paper using a pen. It can be used to create presentation-charts, graphics, tables and high quality technical drawings. There are two types of plotter. Computer Abbreviations.
MS Word Keyboard Shortcuts. Try Computer Quizzes. Sign Up for Free Already have an account? Sign In. Open in App Create free Account. Search for:. Get Pass Pass.
UP Police. AAI JE. VPN: A virtual private network Is a networking technology that involves network tunnels being created between nodes within a public network. Web server: A software application running on a computer that is responsible for serving Web pages on a network. Wireless network: A network that is not constrained by cable and relies on high-frequency radio waves for communication. List and describe three important features of iNetwork.
Explain how iNetwork can be used in the laboratory to enhance teaching and learning computer communication networks. Explain how iNetwork can be configured to capture data traffic from a LAN. List and describe possible enhancements to iNetwork. References Anderson, J.
Diagnostic monitoring of skill and knowledge acquisition. Fredericksen et al. Hillsdale, NJ: Lawrence Earlbaum. Bloom, B. The 2 sigma problem: The search for methods of group instruction as effective as one-to-one tutoring. Educational Researcher, 13, Davis, D. Select the right routing protocol for your network. INetwork 61 Edwards, M. The Mercedes Benz of interactive video. Hardcopy, 14, Lavigne, D. Examining ICMP packets. Larkin Eds. Hillsdale, NJ: Lawrence Erlbaum.
Network Sorcery. RFC sourcebook. Supplementary Communication Networks lecture notes. Sydney, Australia: University of Technology Sydney.
Stallings, W. NJ: Prentice Hall. Because such concepts can be abstract and therefore difficult to visualise and understand, simulation can help facilitate learning. In looking to develop a structured approach to optimally utilising a network simulator in teaching networking concepts, a series of targeted exercises were developed. The background to this, as well as the design and implementation of the exercises, is presented.
Similarly, the features of an appropriate network simulator that can be effectively used in this context are discussed, and a brief overview of the simulation tool used, Packet Tracer, is given. To illustrate the methodology, examples are provided from the actual exercises given to students.
The system was also evaluated through an experiment that measured the improvement in understanding of a particular topic, switched networks, after students participated in a practical on this topic using the exercises discussed. A clear increase in understanding was shown. The incorporation of the simulator in developing case studies to progressively integrate concepts learned as an ongoing, practical exercise is also presented. In addition, the use of simulation to learn troubleshooting skills and strategies by employing a simulated network containing deliberately created errors that need to be resolved is discussed.
Unlike, for instance, the study of program- ming, where many concepts e. In teaching a second-year subject in Internetworking at the Queensland Univer- sity of Technology in Brisbane, we have, like others in this area, sought to overcome these limitations and to enhance the learning experience for our students by utilising various tools and techniques.
These have included simula- tion, visualisation, animation, demonstration, and use of analogy. While such methods generally seem to have a positive effect on the teaching environment and are received favourably by students, two issues have concerned us: whether there were ways in which we could improve our use of these tools, and whether such tools actually aided the learning process and led to a deeper understanding.
Since one of the main tools we use in supporting our teaching is a network simulator, we determined to focus our efforts on developing and evaluating an approach to using simulation in a structured manner, so as to provide a framework to facilitate active independent learning. This does not detract from the use of simulation to demonstrate activities and for stepped, recipe-type exercises, such as router configuration, but represents a specific effort to use the simulator to provide a directed, flexible, and engaging environment for the student to learn independently even when removed from immediate teacher support.
This chapter will outline the way we designed, structured, and implemented a set of practical exercises to achieve this purpose, the nature of the simulation tool we used, and how we evaluated the effectiveness of this approach.
We will further comment on the use of the simulation tool in developing a framework for an ongoing practical exercise linking material together from week to week and using the simulator to teach troubleshooting skills. It should also be emphasized that our approach was geared to working with a large teaching class of to students and that the needs and dynamics are therefore different from working with a small 10 to 15 group in a workshop or lab environment with accessibility to actual network equipment.
The tools that can be used to demonstrate, simulate, or visualise networks and network behaviours lend themselves very readily to teaching in this area.
Some tools, such as network or packet analysers, are utilities employed professionally in the industry, and their very use is in itself is an important skill. Others, such as simulators, are expressly for the purposes of teaching and learning and are generally used to create a specific environment which enables the student or trainee to interact as if in the real situation.
In this respect, simulators can mimic reality very closely. A flight simulator can create an environment so authentic that even sensory stimuli such as motion, sound, and visuals are evident. Others simply provide a representation of the reality in a different format, allowing actions to be observed and demonstrated. For example, a queuing simulator might simply show the behaviour of a queue as a graph of numbers in a queue against time waited in that queue.
Simulators become more effective when parameters can be changed, randomly or specifically, to create different scenarios requiring different responses or reactions from the student. Network simulators usually enable a network to be designed and built dynami- cally as a computer-based graphic by placing network devices as icons on a screen and connecting these devices.
This visualisation in itself immediately makes the material more tangible. A network is then more realistic, even though it is actually a graphic! It makes it easier to understand the components and nature of a genuine network, which we can often see parts of devices, computers, cabling but cannot generally observe in its entirety or at its lower level of operation.
The simulated network can be configured by opening simulated interfaces to the different devices and setting the various parameters required, such as, for example, network interface addresses and gateway addresses. The level of configuration and authenticity of the device interfaces will depend on the sophistication of the simulator.
In the simulator we used, it was possible to configure devices using a simple graphical interface or a console window that very effectively replicated a subset of IOS Internetwork Operating System commands. This will be discussed in greater detail later in the chapter. Educators such as Ramsden , Entwistle , and Biggs distinguish between deep and surface approaches to learning. Just performing tasks in a simulation exercise, while appearing to impart a good understanding, is surface learning and generally does not provide the student with a deep understanding of the issue.
Indeed, student performance over a number of semesters showed no marked difference in understanding between the semesters when the simulator was used and earlier semesters when it was not. The question then asked was, could surface learning be reduced and deep learning increased, particularly when students are working independently, and could we develop a framework, using the simulation tool to effectively implement this?
Salomon believes that the assumption that a tool alone can achieve optimum learning outcomes is misdirected. Perkins and Salomon distinguish between near transfer to closely related contexts and performances and far transfer to rather different contexts and performances. If the objective is to train a student in the operation of a device, this is near transfer and the approach might be to include a series of repetitive tasks.
In considering the pedagogical ap- proach to address this, we felt that the methods suggested in the application of active learning could be incorporated to achieve our objective. Bonwell and Eison explain that a framework that promotes active learning should include higher-order thinking tasks such as problem solving, analysis, synthesis, and evaluation.
Such a framework challenges the student and encourages deeper understanding. There appears to be very little literature that specifically seeks to evaluate the effectiveness of using simulation tools. In the teaching of ICT information and communication technology , it seems that formal evaluation of the effectiveness of teaching tools is often neglected. In our literature survey of the area of data networking, only two papers, Cameron and Yaverbaum and Nadarajan , were found which formally evaluated the teaching innovation they described.
We determined that formal evaluation of the effectiveness of the simulation tool was integral to its use and that we would attempt to actually measure whether any improvement in understanding occurred.
Description of the System The main emphasis of this system is to use the simulation tool as a framework to facilitate and engage the student in active learning. The practical session is therefore structured to promote active learning by progressively leading the student through the concepts incrementally while challenging them to synthesise, interpolate, and apply their evolving knowledge.
As part of this process, students need to be able to assess their answers, receive feedback, and correct any misconceptions before progressing further. For this, the simulator must have functionality that not only allows the student to create, visualise, configure, and manipulate their networks but must also provide a framework for the student to be able to assess their progress through self-evaluation and feedback mecha- nisms.
While any simulator with suitable features could be used, the simulation tool that provided the basis for the implementation in this discussion is Packet Tracer, a network simulator developed by Cisco Systems. Our choice of this product was based on both its powerful and appropriate features and its availability to us.
The suitability of Packet Tracer for use as an interactive learning system was confirmed by mapping it against the 14 pedagogical dimensions described by Reeves Rather, we hope to demonstrate how such a tool can be used to promote active learning.
Any network simulation program that can provide similar features could be used. A key feature of the simulation tool used is that it should be easy to work with and, if possible, fun to use since students should not be distracted from the learning objectives by having to contend with a complex system.
In other words, the means should not transcend the ends. Furthermore, the simulator should accurately and adequately mimic the reality. While, understandably, a simulator might not be able to include every possible feature available in the actual device, the subset provided must be sufficient so as to make the interaction meaningful.
In other words, it would be pointless to provide a simulation of IOS without including commands to configure an interface! Similarly, the operation of the simulator must be accurate. Again, for example, if a packet is incorrectly routed to its destination, it would mislead and confuse the students. Packet Tracer is a powerful, highly visual, but simple-to-use network simulation application. It enables a simulated network to be built in a topography view see Figure 1 by connecting a range of network devices routers, switches, bridges, hubs, servers, and PCs together using a variety of connection media.
These devices can then be appropriately configured. Interfaces can be set and routing tables can be built. The network created can be extensive or simple, and the specific functionality of individual devices is also available. For example, switches can be used to implement virtual local area networks VLANs. In simulation mode, Packet Tracer enables data packets to be created and sent from device to device.
The behaviour of the packet and the path it follows are Figure 1. Simulation view showing failure of data transmission Figure 3. Simulation showing packet information and routing table animated and simulate the way a packet will act in an actual network. Errors in the network configuration, for example, incorrect routes, will therefore cause a data transmission to fail, and this is shown in the visualisation see Figure 2.
Furthermore, at each hop in a transmission, the state of the transmission as well as the message headers in a packet can be examined. Device information can also be viewed see Figure 3. Devices such as routers can even be configured using IOS commands through a console window see Figure 4.
Console window allowing router configuration using IOS This makes it a powerful tool not only for practicing network configuration but also for investigating network behaviour.
By observing the network activity and then analysing the network and packet status, the cause and effect of a particular configuration or setting can be identified, confirmed, and understood.
This capability lends itself strongly to the use of Packet Tracer to facilitate active learning. We believe that the ability of Packet Tracer to give students meaningful intrinsic feedback is one of the keys to why this tool effectively supports independent learning.
Packet Tracer networks, including their configurations, can be saved and stored as files. Multiple networks can therefore be used.
For example, two versions of the same network can be built and then compared. Similarly, a network can be modified and extended over a period of time as more and more concepts are learned. This feature is used to build an integrated, ongoing exercise and will be elaborated on further in this chapter.
In addition, Packet Tracer allows scenarios to be built and saved. A scenario is essentially a stored animation within a simulated network that can be run anytime and be observed. Together with the analytical features within Packet Tracer already referred to, this feature plays a crucial role in facilitating active learning since specific actions can be modelled and then analysed. An example of this will be given further in this chapter. If possible, the topics should be structured so that the fundamental concepts are initially presented and then used as the basis to incrementally and logically move to more complex topics.
A simulated network is then built that includes components illustrating the concepts being targeted. For example, if considering routing, the question might ask what path a packet might follow as it is routed across the network from a particular source to a particular destination. For each question, a scenario is included which in essence provides an animation of the activity referred to in the question.
In the example above, this animation would show a packet actually being sent through the path referred to. So, if the question asked how a packet would be routed from node A to node B, the corresponding scenario would actually show this as a simulated packet sent from A to B.
While not directly presenting a solution, the animation would enable the student to determine what actually happens by observing the action.
This would either confirm their understanding or encourage them to ascertain why their assess- ment was not correct. To do this they would be able to analyse the action and infer what should be happening by examining headers, consulting notes, rerun- ning the action in steps, changing the action and observing differences, and generally interacting with the resources available. The main thing is that they are actively seeking the solutions. Where predefined scenarios are not suitable, students can be asked to modify their network this provides practice in network configuration and then asked about the effect that these changes will bring.
The student can also create a scenario in the changed network to enable them to test and investigate these effects. So if, for example, subnets were added to the network, the students would be able to build a scenario sending a packet to the subnet and examining how this impacts on the network. The sequence of the exercises is quite simple but important. Students are asked to open the simulated network in the simulator, examine the network in its visualised form first, and then answer the questions about the specific topic.
They are then able to switch to the simulation mode and run the animated scenarios that relate to each question to confirm and evaluate their responses. If their assessment is not correct, then, by analysing the scenario and looking at the device or packet configuration at each step of the process, they are able to learn what went wrong and why.
In this way the simulation provides them with the framework for analysis, feedback, synthesis, and evaluation. On completion of the topic, a broader question is presented which leads them to the next topic. To illustrate this we will look at two exercises taken from a practical given as part of the normal course work of the unit. The practical exercises were then based on five concepts taken from this topic area. For each of the concepts, a separate Packet Tracer network and configuration were built.
Similarly, for each concept, a series of questions was designed to test under- standing of that concept remembering that this had already been introduced in the lecture. For each question on a concept, a simulated scenario was included that implemented and demonstrated the situation referred to in the question.
Furthermore the structure of these practical exercises was fairly uniform in order to encourage students to be methodical in their approach. Below are the two actual exercises. Images of the visualised networks are also shown although these would have been viewed by the students directly in Packet Tracer.
The introduction to the exercises briefly presents the objectives and explains the processes and rationale involved. It should be remembered that the exercises were part of the normal program for this unit, so the material had already been presented in a lecture and the students were familiar with the general conduct of the practicals and with using Packet Tracer.
The first exercise is straightforward and clearly illustrates the methodology and use of predefined scenarios. The second exercise is somewhat more complex and requires that the students modify their networks and then create their own scenarios to analyse network processes, in this case, inter-VLAN routing. Students were given detailed information on how to modify their networks. This was because the objective was to achieve an understanding of the concepts involved rather than focusing on configuration changes that needed to be made.
You will then be able to run a number of predefined scenarios for the network, observing and analysing the resultant actions. This will further help you understand your answers and, where necessary, correct these. In some cases you will be required to modify the network topography and configuration and then observe the effects of these changes. The networks are all related to each other, and so you will be able to see how progressive changes in the network topography and architecture impact on network behaviour.
In order to derive the most benefit from these exercises, you should do these in sequence and not jump ahead since subsequent exercises and situations relate to previous ones. Answer the following questions: 1.
If a packet is sent from PC1 to PC4, what path will the packet travel and why? If a packet is broadcast from PC2, what path will that packet travel and why? Exercise 1, initial network Figure 6. Scenario for Question 4 showing a collision 3. What is the difference between the two actions in 1 and 2 above and why? What happens to the packet sent? If one packet is sent from PC3 and another from PC5 at the same time, what will occur and why? Each scenario corresponds to the situation outlined in the previous questions, for example, Scenario 1 relates to Question 1, but for Question 3, consider both Scenarios 1 and 2.
At the end of each scenario, consider whether the action you observed agrees with the action you thought would occur. If not, try to determine what is occurring and where your assessment was wrong. To help, run the scenarios in step mode and click on the packet at each stage to see what is happening at each protocol layer at that stage and what the state of the transmission is.
Answer the following question based on your observations from the scenarios shown: Question The above network demonstrates a collision domain. Why is this? In this instance is there any difference between a collision domain and broadcast domain?
Each VLAN must be considered as a separate network or subnet with an appropriate network id, and routing must be implemented to send data from one VLAN to another. Refer again to the network in Packet Tracer. In topology mode now add a router. This can be done by simply connecting two ports on the switch to two separate interfaces on the router and configuring these ports to be in VLAN1 and VLAN2.
Connect the router to the switch. The connection should be between Interface 0 on the router and Port 6 on the switch. Note: Now make another connection. This connection should be between Interface 1 on the router and Port 7 on the switch. On the router now configure Interface 0 with the IP address Configure Interface 1 with the IP address Note: Usually a router will be configured on a single trunk and the interface for each VLAN configured as a subinterface.
Traffic for each VLAN is then identified through frame tagging. The net result, however, is the same as the configuration we have implemented. What will happen when a packet is sent from PC0 to PC2? Now create a packet to do this and confirm your answer. What path does a packet sent from PC1 to PC5 take to reach its destination? Explain each stage.
Now create a packet to do this and analyse the path by stepping through this action and examining the packet state at each stage. What path would a packet broadcast on VLAN2 follow and why? Now create a broadcast packet from PC4 to do this and observe what happens to confirm your answer. End Practical Exercises Continuing Practice To further utilise the simulation and to enhance deeper learning, an ongoing exercise was developed as a case study to progressively build an expanding network.
This network was changed and enhanced to reflect the topics, concepts, and processes that were discussed from week to week. In this way, new ideas were incorporated into the network in a logical and contextual manner. There was continuity, and students were led to an understanding of how new concepts and processes fitted into the network as it grew in complexity. Rather than focusing on the concepts and processes in isolation, the objective was to focus on how they were integrated in a network and the function they fulfilled in that network.
In week 1 the idea of a simple, single segment network was introduced and then simulated in Packet Tracer. This was used to illustrate the concepts of network connectivity, direct delivery, and simple addressing. Later again, the network changed and grew to reflect the inclusion of features such as subnetting, switching, and Network Address Translation NAT. To provide a context for this expanding network, a story line was maintained which followed the growth of a fictitious company as it developed and required changes and more sophisticated functionality from its network.
NAT was introduced when the company required external Internet access. To the student this made the material more relevant, provided a meaningful context as well as a sense of achievement as they saw their work grow. The features available in Packet Tracer also enable the simulator to be used to develop troubleshooting skills in students.
Students are given simulated networks with errors in them. They use scenarios to test the network and then, when problems are found, identify these by analysing the details available from Packet Tracer about packet headers, state information, IP addresses, and routing tables. The errors can be corrected within Packet Tracer and immediately checked. Students can therefore learn how to check their networks, identify which errors can occur, how these are manifested, and how they can be corrected.
For example, a network can be provided to the students with a number of scenarios animations , each of which fail. These scenarios could include: invalid or missing gateway on a PC, invalid TTL time-to-live in a packet, invalid IP address, route missing, no default route, invalid subnet address or incorrect subnet mask used, trunking not configured in a switch, VLANs not correctly assigned, incorrect cabling used, or invalid NAT configuration.
Faulty hardware can even be simulated by leaving a device in the simulation in an off state. Using these scenarios the students can develop troubleshooting strategies and an understand- ing of the errors involved. Later in an assessment exercise, students can be provided with a network with similar errors and be asked to locate, identify, and correct these using the troubleshooting strategies they had developed.
Usefulness and Benefits The benefit in using this approach is that students are involved in active learning. They are required to think deeply about what they are doing and what is occurring, and as they work through the exercises they get rapid feedback from the simulator. The simulation tool provides a hands- on, practical environment which engages the student and is more exciting and real because of the use of relevant visuals and animations.
Material can be placed in a context, continuity can be achieved, and analytical and troubleshoot- ing skills can be developed. Students seek understanding and explanation through analysing, synthesising, and extrapolating information and knowledge through dynamic interaction with the system rather than just being told. Students can therefore work more effectively and independently.
Finally, in terms of data communication, the system enables concepts and process that are otherwise esoteric to be made more tangible and accessible and, ultimately, more under- standable.
While it was clear that students enjoyed using Packet Tracer and found the exercises engaging, we also wanted to determine whether the use of simulation in such an active learning framework did indeed improve their understanding of the concepts presented. Our evaluation strategy was based on the framework developed by Naps et al. The evaluation included a pretest, a posttest, a student background questionnaire, and learner feedback questions.
The pre- and posttests were isomorphic. The same questions were used in each test but in a different order. Students attended normal practical sessions, but at the start of the session that was used to assess the exercises, they were tested to determine their current understanding of the material by completing a pretest multiple-choice question- naire.
Since Packet Tracer was used as an integral part of all the practical classes in the subject and students were familiar with its functionality and operation, there was no need to focus on its operation. After the students completed the practical exercises as discussed in this chapter, they were given a posttest similar to the initial pretest.
We found that student understanding appeared to improve considerably following completion of the practical. Paired-samples statistics Mean N Std.
Deviation Std. Printers are classified on the basis of a number of parameters like, the mechanism used for printing, speed of printing, quality of output, direction of printing, and the kind of interface they have with the computer. Printers can be broadly classified as impact and non-impact printers. Let us understand this in detail. Impact Printers Impact printers work like typewriters. The characters are printed by striking the paper i.
Impact printers can again be classified as Character printers and Line printers. Character Printers Character printers print one character at a time. Examples of character printers are. In a DMP, tiny hammers or pins strike the ribbon to produce the desired characters. The print head consists of 9x7 arrays of pins. Characters to be printed are sent one at a time to the printer. The characters printed are a series of dots.
Dot- matrix printers are inexpensive but noisy. They can print both text and graphics. They can print in any language without additional hardware change. They can also be made to print in colour by changing ribbons. These printers are used everywhere to produce internal reports and memos needed by organizations.
Daisy Wheel Printer In a daisy wheel printer, each petal has a character embossed on it. A motor spins the wheel along with it. When the desired character spins to the correct position, a print hammer strikes it to produce a character. Line printers Line printers print one line at a time. Hence, line printers are generally faster than character printers.
Printing speed varies from lines to lines per minute. Some of the line printers are drum printers and chain printers. These can continuously print for a few hours. Drum printers A drum printer consists of a cylindrical drum. The characters to be printed are embossed on it. A set of print hammers one for each character in a line, are mounted in front of the drum. A character is printed by striking the appropriate hammer against the embossed character on the surface.
The drum completes one revolution to print one line. The movement of the drum and the striking of the hammer must synchronize. Otherwise, the printing will not be uniform. As printer drums are costly they cannot be changed often. Chain Printer A chain printer has a steel band on which the characters are embossed.
The band is rotated at a high speed. As the band rotates, a hammer is activated when the desired character comes in front of it. For every character there will be a hammer. Here also, the hammer movement and the chain movement must be synchronized.
The main advantage of the chain printer is that its chain can be easily changed. Thus, different fonts and scripts can be used with the same printer.
Some examples of the non-impact are laser printer, thermal printer, and inkjet printer. Laser Printer Laser printers print one page at a time.
Laser printers use a light beam to form images on the paper using a toner ink as the medium. Laser printers are quiet workers. They produce very high quality output both text and graphics. They are typically used publishing. Other Non-impact printers The other types of non-impact printers are thermal printers which use heat to print characters on paper and inkjet printers which use jets of ink to print characters on paper. These printers are not in use as much as the laser printers.
It can be used to create presentation-charts, graphics, tables and high quality technical drawings. There are two types of plotters: Drum and Flat Bed plotter. Drum Plotter The paper is placed over the drum that rotates back and forth. A carriage holding one or more pens is mounted horizontally across the drum. The carriage with the pens moves horizontally over the paper. Each pen could be filled with different colours. This plotter has the ability to produce colour pictures. Flat Bed Plotter In flat bed plotter, the paper does not move.
The carriage holding the pens should provide all motions. Inkjet plotters can also produce large drawings with different colours. The system unit consists of primary storage, arithmetic-logic unit, and the control unit. The CPU interprets instructions to the computer, performs the logical and arithmetic processing operations, and causes the input and output operations to occur.
It acts like the central nervous system for all the components though; it does not process any data. These separate areas are not fixed. The size of each area varies from application to application.
ON state is represented by 1 and OFF state is represented by 0. A collection of 8 bits is known as a byte. One Kilobyte represents bytes and one Megabyte represents Kilobytes. Ram Random Access Memory RAM is the area that is used for holding the programs and their data while the computer is working with them.
RAM means the memory can be read from and written to randomly. These sets of programs perform the most basic control and supervisory operations for the computer. But the storage devices are not as fast as the CPU. Most of the time the CPU has to slow down because of these devices. A small section of the high speed RAM is used to keep frequently needed information. So, one need some storage device to store data and other information.
It should be cheap and should not lose the content when power is switched off. This storage is called as the secondary storage. All secondary storage devices act both as input and output devices. Magnetic storage media fulfils these requirements and most common storage devices are disks and tapes. Floppy Disk It is the most common storage media and it helps transferring the data from one computer to another. Data is stored in these sectors.
Each piece of data that is stored, has a track number, a sector number and side number as an address. So data can be accessed randomly from anywhere on the disk. Hence, it is also called as Random Access storage. The most significant difference between a floppy disk and a hard disk is that the hard-disk is completely sealed and is protected from dust and airborne particles. The name hard disk comes from the rigid platter that is inside the drive.
This is, often called by different names like fixed disk or Winchester disk. The hard disk comes in different shapes. Most hard disks nowadays store something close to MB. Magnetic Tapes Apart from using disks for external storage purposes, magnetic tapes are also used for storing large amount data.
The magnetic tape could be a large reel or a small cassette. The tape is essentially a plastic ribbon coated with some material that can be magnetized. The data is recorded on these magnetic spots.
The data on the tape can however be read or written sequentially only. Hence, it is called as sequential access storage. The computer bus consists of two parts, the address bus and a data bus. The data bus transfers actual data, whereas the address bus transfers information about where the data should go.
VDUs can work in two different modes viz. Text mode and graphic mode. In text mode, the screen is divided into a matrix of rows and columns; each cell of the matrix is used for one character. A typical screen has 80 character positions per line and 25 lines across the screen. In graphic mode, the screen is treated as an array of tiny dots called pixels.
The characters and pictures that appear on the screen are shown by making a drawing of these pixels. The number of dots on the screen is called as resolution. The higher the resolution the better the picture.
A typical high resolution monitor has x pixels across the screen. The formation of images on the screen is handled by the Video Controller.
The Video Controller along with the memory that holds the display- data are together referred to as display adaptors. Though these details do not affect you as an end user, it completes your knowledge of the computer. System Unit It is a box like structure of the computer. Inside this box you can find the power supply, storage device, hard disk and floppy drives, and the motherboard containing CPU and memory.
It can also contain optional cards like the modem card, mouse card, video card, sound card. System unit or Main unit or Console comes in two styles.
These PDF files also contain exercises , examples of practical work and other things that will make the learning process easier and simpler. All it takes is a computer, access to the Internet and of course — patience and willpower.
As previously mentioned, you can do some research and find other attractive PDF tutorials too. Computer PDF is here to help you learn programs, enhance your knowledge in computer security, databases, office, automation, analytics and IT in general.
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