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WORD COUNT : 3889
System Software is the of program that controls and supports the computer hardware and its information processing activities. Basically, system software can grouped into 3 major functional categories. Discuss.
The OSI model defines a networking framework to implement protocols in seven layers and each specifying particular network function. List and explain the functions of each layer.
Table of Contents
An organized approach to the study of the information needs of an organization's management at every level in making operational, tactical, and strategic decisions. Its objective is to design and implement procedures, processes, and routines that provide suitably detailed reports in an accurate, consistent, and timely manner.
In a management information system, modern, computerized systems continuously gather relevant data, both from inside and outside an organization. This data is then processed, integrated, and stored in a centralized database (or data warehouse) where it is constantly updated and made available to all who have the authority to access it, in a form that suits their purpose.
First question is about System Software is the of program that controls and supports the computer hardware and its information processing activities. Explain the 3 major functional categories in system software. Second question is about the OSI model defines a networking framework to implement protocols in seven layers and each specifying particular network function. List and explain the functions of each layer.
Question 1: System Software is the of program that controls and supports the computer hardware and its information processing activities. Basically, system software can grouped into 3 major functional categories. Discuss.
What is System Software
System software (or systems software) is computer software or an operating system designed to operate and control the computer hardware and to provide a platform for running application software. Device drivers such as computer BIOS and device firmware provide basic functionality to operate and control the hardware connected to or built into the computer. The operating system (prominent examples being z/OS, Microsoft Windows, Mac OS X and Linux), allows the parts of a computer to work together by performing tasks like transferring data between memory and disks or rendering output onto a display device. It also provides a platform to run high-level system software and application software. Window systems are components of a graphical user interface (GUI), and more specifically of a desktop environment, which supports the implementation of window managers, and provides basic support for graphics hardware, pointing devices such as mouse, and keyboards. The mouse cursor is also generally drawn by the windowing system. Utility software helps to analyze, configure, optimize and maintain the computer.
System software refers to the files and programs that make up your computer's operating system. System files include libraries of functions, system services, drivers for printers and other hardware, system preferences, and other configuration files. The programs that are part of the system software include assemblers, compilers, file management tools, system utilites, debuggers.
System software is a program that manages and supports the computer resources and operations of a computer system while it executes various tasks such as processing data and information, controlling hardware components, and allowing users to use application software. That is, systems software functions as a bridge between computer system hardware and the application software. System software is made up of many control programs, including the operating system, communications software and database manager. There are many kinds of computers these days. Some of them are easier to learn than others. Some of them perform better than others. These differences may come from different systems software. It helps in running computer hardware and the computer system. System software refers to the operating systems; device drivers, servers, windowing systems and utilities. System software helps an application programmer in abstracting away from hardware, memory and other internal complexities of a computer. An operating system provides users with a platform to execute high-level programs.
System software is responsible for managing a variety of independent hardware components, so that they can work together harmoniously. Its purpose is to unburden the application software programmer from the often complex details of the particular computer being used, including such accessories as communications devices, printers, device readers, displays and keyboards, and also to partition the computer's resources such as memory and processor time in a safe and stable manner.
Three major functional of system software
The three major functions of system software are allocating system resources, monitoring system activities, and disk and file management.
1. Allocating system resources: The system resources are time, memory, input, and output. The time in the CPU is divided into time slices. The time slices is measured in terms of milliseconds. Based on the priority of tasks the time slices are assigned. Memory is also managed by operating system. Disk space is the part of main memory. The data flow is controlled by operating system. This is an alternate view about the services performed by the OS. The OS system provides an orderly and controlled allocation of the processors, memories and I/O devices.
When a computer has multiple users the need for managing and protecting the memory, I/O devices and other devices is greater. Thus the primary task of OS is to keep track of who is using which resource, to grant resource requests, to mediate conflicting requests from different programs. Resource management includes multiplexing resources in two ways - "in time" and "in space". When a resource is time multiplexed different programs or different users gets their turn to use that resource. eg: Printer.When a resource is space multiplexed instead of taking turns, the resource is shared among them, ie each one gets a part of the resource. Sharing main memory, hard disk. The operating system directs the traffic inside the computer, deciding what resources will be used and for how long.
Time in the CPU is divided into time slices which are measured in milliseconds. Each task the CPU does is assigned a certain number of time slices. When time expires, another task gets a turn. The first task must wait until it has another turn. Since time slices are so small, you usually can't tell that any sharing is going on. Tasks can be assigned priorities so that high priority (foreground) tasks get more time slices than low priority (background) tasks.
Memory must be managed also by the operating system. All those rotating turns of CPU use leave data waiting around in buffers. Care must be taken not to lose data!! One way to help out the traffic jam is to use virtual memory. This includes disk space as part of main memory. While it is slower to put data on a hard disk, it increases the amount of data that can be held in memory at one time. When the memory chips get full, some of the data is paged out to the hard disk. This is called swapping. Windows uses a swap file for this purpose.
Flow control is also part of the operating system's responsibilities. The operating system must manage all requests to read data from disks or tape and all writes to these and to printers. When you click the mouse while the web cam is streaming, the operating system must control what happens and when. To speed up the output to printers, operating systems now allow for print spooling, where the data to be printed is first put in a file. This frees up the processor for other work in between the times data is going to the printer. A printer can only handle so much data at a time. Without print spooling you'd have to wait for a print job to finish before you can do anything else. With it you can request several print jobs and go on working. The print spool will hold all the orders and process them in turn.
2.Monitoring system activities: The system security and system performance is monitored by system software. System performance includes response time and CPU utilization. System security is a part of operating system. Multiple users can’t access without the security code or password. A user or administrator can check to see whether the computer or network is getting overloaded. Changes could be made to the way tasks are allocated or maybe a shopping trip is in order!
System performance would include response time ( how long it takes for the computer to respond when data is entered) and CPU utilization (comparing the time the CPU is working to the time it is idle.) Monitoring the performance of operating systems and processes is essential to debug processes and systems, effectively manage system resources, making system decisions, and evaluating and examining systems. These tools are primarily divided into two main categories: real time and log-based. Real time monitoring tools are concerned with measuring the current system state and provide up to date information about the system performance. Log-based monitoring tools record system performance information for post-processing and analysis and to find trends in the system performance. This paper presents a survey of the most commonly used tools for monitoring operating system and process performance in Windows- and Unix-based systems and describes the unique challenges of real time and log-based performance monitoring. Some system security is part of the operating system, though additional software can add more security functions. For multiple users who are not all allowed access to everything, there must be a logon or login procedure where the user supplies a user name or ID and a secret password. An administrator must set up the permissions list of who can have access to what programs and what data.
3. File and disk management: The user needs to save, copy, delete, move and rename the files. The system software will handle those functions. Disk and file management is the technical task. Keeping track of what files are where is a major job. If you can't find a file, it doesn't help to know that it is safe and secure somewhere. So an operating system comes with basic file management commands. A user needs to be able to create directories for storing files. A user needs to copy, move, delete, and rename files. This is the category of operating system functions that the user actually sees the most.
A more technical task is that of disk management. Under some operating systems your hard disk can be divided up, or partitioned into several virtual disks. The operating system treats each virtual disk as though it were a physically separate disk. Managing several physical and/or virtual disks can get pretty complex, especially if some of the disks are set up with different operating systems.
Question 2: The OSI model defines a networking framework to implement protocols in seven layers and each specifying particular network function. List and explain the functions of each layer
What is OSI Model
The OSI model defines internetworking in terms of a vertical stack of seven layers. The upper layers of the OSI model represent software that implements network services like encryption and connection management. The lower layers of the OSI model implement more primitive, hardware-oriented functions like routing, addressing, and flow control.
In the OSI model, data communication starts with the top layer at the sending side, travels down the OSI model stack to the bottom layer, then traveses the network connection to the bottom layer on the receiving side, and up its OSI model stack.
The OSI model was introduced in 1984. Although it was designed to be an abstract model, the OSI model remains a practical framework for today's key network technologies like Ethernet and protocols like IP.
The OSI (Open Systems Interconnection) model was created by the ISO to help standardize communication between computer systems. It divides communications into seven different layers, which each include multiple hardware standards, protocols, or other types of services.
The seven layers of the OSI model include:
The Physical layer
The Data Link layer
The Network layer
The Transport layer
The Session layer
The Presentation layer
The Application layer
When one computer system communicates with another, whether it is over a local network or the Internet, data travels through these seven layers. It begins with the physical layer of the transmitting system and travels through the other layers to the application layer. Once the data reaches the application layer, it is processed by the receiving system. In some cases, the data will move through the layers in reverse to the physical layer of the receiving computer.
The best way to explain how the OSI model works is to use a real life example. In the following illustration, a computer is using a wireless connection to access a secure website.
Layer 1: physical layer
Physical Layer is responsible for transmitting row bit stream over the physical cable. The physical layer defines the hardware items such as cables, cards and voltages.The physical layer defines electrical and physical specifications for devices. In particular, it defines the relationship between a device and a transmission medium, such as a copper or fiber optical cable. This includes the layout of pins, voltages, line impedance, cable specifications, signal timing, hubs, repeaters, network adapters, host bus adapters (HBA used in storage area networks) and more.
The major functions and services performed by the physical layer are:
Establishment and termination of a connection to a communications medium.
Participation in the process whereby the communication resources are effectively shared among multiple users. For example, contention resolution and flow control.
Modulation or conversion between the representation of digital data in user equipment and the corresponding signals transmitted over a communications channel. These are signals operating over the physical cabling (such as copper and optical fiber) or over a radio link.
Parallel SCSI buses operate in this layer, although it must be remembered that the logical SCSI protocol is a transport layer protocol that runs over this bus. Various physical-layer Ethernet standards are also in this layer; Ethernet incorporates both this layer and the data link layer. The same applies to other local-area networks, such as token ring, FDDI, ITU-T G.hn and IEEE 802.11, as well as personal area networks such as Bluetooth and IEEE 802.15.4.
Layer 2: data link layer
The data link layer provides the functional and procedural means to transfer data between network entities and to detect and possibly correct errors that may occur in the physical layer. Originally, this layer was intended for point-to-point and point-to-multipoint media, characteristic of wide area media in the telephone system. Local area network architecture, which included broadcast-capable multi-access media, was developed independently of the ISO work in IEEE Project 802. IEEE work assumed sublayer-ing and management functions not required for WAN use. In modern practice, only error detection, not flow control using sliding window, is present in data link protocols such as Point-to-Point Protocol (PPP), and, on local area networks, the IEEE 802.2 LLC layer is not used for most protocols on the Ethernet, and on other local area networks, its flow control and acknowledgment mechanisms are rarely used. Sliding window flow control and acknowledgment is used at the transport layer by protocols such as TCP, but is still used in niches where X.25 offers performance advantages.
The ITU-T G.hn standard, which provides high-speed local area networking over existing wires (power lines, phone lines and coaxial cables), includes a complete data link layer which provides both error correction and flow control by means of a selective repeat Sliding Window Protocol.
Both WAN and LAN service arrange bits from the physical layer into logical sequences called frames. Not all physical layer bits necessarily go into frames, as some of these bits are purely intended for physical layer functions. For example, every fifth bit of the FDDI bit stream is not used by the layer. Following are the functions of data link layer:-
Media Access Control(MAC)
WAN protocol architecture
Connection-oriented WAN data link protocols, in addition to framing, detect and may correct errors. They are also capable of controlling the rate of transmission. A WAN data link layer might implement a sliding window flow control and acknowledgment mechanism to provide reliable delivery of frames; that is the case for Synchronous Data Link Control (SDLC) and HDLC, and derivatives of HDLC such as LAPB and LAPD.
IEEE 802 LAN architecture
Practical, connectionless LANs began with the pre-IEEE Ethernet specification, which is the ancestor of IEEE 802.3. This layer manages the interaction of devices with a shared medium, which is the function of a media access control (MAC) sublayer. Above this MAC sublayer is the media-independent IEEE 802.2 Logical Link Control (LLC) sublayer, which deals with addressing and multiplexing on multi-access media.
While IEEE 802.3 is the dominant wired LAN protocol and IEEE 802.11 the wireless LAN protocol, obsolete MAC layers include Token Ring and FDDI. The MAC sublayer detects but does not correct errors.
Layer 3: network layer
The network layer provides the functional and procedural means of transferring variable length data sequences from a source host on one network to a destination host on a different network (in contrast to the data link layer which connects hosts within the same network), while maintaining the quality of service requested by the transport layer. The network layer performs network routing functions, and might also perform fragmentation and reassembly, and report delivery errors. Routers operate at this layer, sending data throughout the extended network and making the Internet possible. This is a logical addressing scheme – values are chosen by the network engineer. The addressing scheme is not hierarchical.
The network layer may be divided into three sublayers:
Subnetwork access – that considers protocols that deal with the interface to networks, such as X.25;
Subnetwork-dependent convergence – when it is necessary to bring the level of a transit network up to the level of networks on either side
Subnetwork-independent convergence – handles transfer across multiple networks.
An example of this latter case is CLNP, or IPv6 ISO 8473. It manages the connectionless transfer of data one hop at a time, from end system to ingress router, router to router, and from egress router to destination end system. It is not responsible for reliable delivery to a next hop, but only for the detection of erroneous packets so they may be discarded. In this scheme, IPv4 and IPv6 would have to be classed with X.25 as subnet access protocols because they carry interface addresses rather than node addresses.
A number of layer-management protocols, a function defined in the Management Annex, ISO 7498/4, belong to the network layer. These include routing protocols, multicast group management, network-layer information and error, and network-layer address assignment. It is the function of the payload that makes these belong to the network layer, not the protocol that carries them.
Layer 4: transport layer
The transport layer provides transparent transfer of data between end users, providing reliable data transfer services to the upper layers. The transport layer controls the reliability of a given link through flow control, segmentation/desegmentation, and error control. Some protocols are state- and connection-oriented. This means that the transport layer can keep track of the segments and retransmit those that fail. The transport layer also provides the acknowledgement of the successful data transmission and sends the next data if no errors occurred.
OSI defines five classes of connection-mode transport protocols ranging from class 0 (which is also known as TP0 and provides the least features) to class 4 (TP4, designed for less reliable networks, similar to the Internet). Class 0 contains no error recovery, and was designed for use on network layers that provide error-free connections. Class 4 is closest to TCP, although TCP contains functions, such as the graceful close, which OSI assigns to the session layer. Also, all OSI TP connection-mode protocol classes provide expedited data and preservation of record boundaries. An easy way to visualize the transport layer is to compare it with a Post Office, which deals with the dispatch and classification of mail and parcels sent. Do remember, however, that a post office manages the outer envelope of mail. Higher layers may have the equivalent of double envelopes, such as cryptographic presentation services that can be read by the addressee only. Roughly speaking, tunneling protocols operate at the transport layer, such as carrying non-IP protocols such as IBM's SNA or Novell's IPX over an IP network, or end-to-end encryption with IPsec. While Generic Routing Encapsulation (GRE) might seem to be a network-layer protocol, if the encapsulation of the payload takes place only at endpoint, GRE becomes closer to a transport protocol that uses IP headers but contains complete frames or packets to deliver to an endpoint. L2TP carries PPP frames inside transport packet.
Although not developed under the OSI Reference Model and not strictly conforming to the OSI definition of the transport layer, the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) of the Internet Protocol Suite are commonly categorized as layer-4 protocols within OSI.
Layer 5: session layer
The session layer controls the dialogues (connections) between computers. It establishes, manages and terminates the connections between the local and remote application. It provides for full-duplex, half-duplex, or simplex operation, and establishes checkpointing, adjournment, termination, and restart procedures. The OSI model made this layer responsible for graceful close of sessions, which is a property of the Transmission Control Protocol, and also for session checkpointing and recovery, which is not usually used in the Internet Protocol Suite. The session layer is commonly implemented explicitly in application environments that use remote procedure calls.
Layer 6: presentation layer
The presentation layer establishes context between application-layer entities, in which the higher-layer entities may use different syntax and semantics if the presentation service provides a mapping between them. If a mapping is available, presentation service data units are encapsulated into session protocol data units, and passed down the stack.
This layer provides independence from data representation (e.g., encryption) by translating between application and network formats. The presentation layer transforms data into the form that the application accepts. This layer formats and encrypts data to be sent across a network. It is sometimes called the syntax layer.
The original presentation structure used the Basic Encoding Rules of Abstract Syntax Notation One (ASN.1), with capabilities such as converting an EBCDIC-coded text file to an ASCII-coded file, or serialization of objects and other data structures from and to XML.
Layer 7: application layer
The application layer is the OSI layer closest to the end user, which means that both the OSI application layer and the user interact directly with the software application. This layer interacts with software applications that implement a communicating component. Such application programs fall outside the scope of the OSI model. Application-layer functions typically include identifying communication partners, determining resource availability, and synchronizing communication. When identifying communication partners, the application layer determines the identity and availability of communication partners for an application with data to transmit. When determining resource availability, the application layer must decide whether sufficient network or the requested communication exist. In synchronizing communication, all communication between applications requires cooperation that is managed by the application layer. Some examples of application-layer implementations also include:
On OSI stack:
FTAM File Transfer and Access Management Protocol
Common Management Information Protocol (CMIP)
On TCP/IP stack:
Hypertext Transfer Protocol (HTTP),
File Transfer Protocol (FTP),
Simple Mail Transfer Protocol (SMTP)
Simple Network Management Protocol (SNMP).
Management information system used to process, store, and transmit information that supports Antitrust Division operations for management and support, and historic mission-specific purposes. Securing this information and assuring its proper use is critical to the success of these operations. Management information system applications are secured via access authorization, authentication rules, and audit controls. These technical controls are supplemented by procedural controls such as Account Management Reviews, Rules of Behavior, Confidentiality Agreements, and Security Awareness and Training to mitigate risks regarding unauthorized access and subsequent potential privacy violations. Basic computer concepts have been explained. The advantages and disadvantages of centralized versus decentralized systems have been examined. The need for organizing databases and their integration and the need for programmes for decision analysis to evolve a decision support system have been explained. The Open Systems Interconnect (OSI) model has seven layers. This article describes and explains them, beginning with the 'lowest' in the hierarchy (the physical) and proceeding to the 'highest' (the application).
Management Information System Author: Sarngadharan, M. Minimol, M.C.
Publisher: Himalaya Publishing House Original Publication Date: 2010
Subjects: Management information system
Moodle as a Curriculum and Information Management System. Author: Hollowell, Jason .Publisher: Packt Publishing Ltd Original Publication Date: 01/2011
Subjects: Instructional systems -- Design. Computer-assisted instruction -- Computer programs.
Pathways to Institutional Improvement with Information Technology in Educational Management . Author: Nolan, C. J. Patrick Fung, Alex C. W. Brown, Margaret A.
Publisher: Kluwer Academic Publishers Original Publication Date: 09/2001
Subjects: School management and organization -- Data processing -Congresses. Information technology -- Congresses.
Software Design Methodology : From Principles to Architectural Styles ebrary Reader
Author: Zhu, Hong . Available through: Olympia College eLibrary website
Management Information System ebrary Reader Author: Sarngadharan, M. Minimol, M.C. Available through: Olympia College eLibrary website
How to Set Up and Run Information Systems : A Non-Specialist's Guide ebrary Reader Author: Bell, Simon Wood-Harper, A. T. Available through: Olympia College eLibrary website
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Management information system. Available at:
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