Operating System Case Study no. 3

Security Problems in Multiprogramming and Time-Sharing Environment

Multiprogramming is one of the more basic types of parallel processing that can be employed in many different environments. Essentially, multiprogramming makes it possible for several programs to be active at the same time, while still running through a single processor. The functionality of multiprogramming in this environment involves a continual process of sequentially accomplishing tasks associated with the function of one program, then moving on to run a task associated with the next program.

In multiprogramming, concurrent running (sharing of the processor) is achieved when the operating system identifies opportunities to interrupt the handling of one program between tasks (e.g., when it is waiting for input/output) and to transfer process control to another program (application, job or user). To a great extent, the ability of a system to share its resources equitably—or according to certain priorities—is dependent upon the design of the programs being handled and how frequently they may be interrupted.

On the other hand, time-sharing is the sharing of a computing resource among many users by means of multiprogramming and multi-tasking. Its introduction in the 1960s, and emergence as the prominent model of computing in the 1970s, represents a major technological shift in the history of computing.

By allowing a large number of users to interact concurrently with a single computer, time-sharing dramatically lowered the cost of providing computing capability, made it possible for individuals and organizations to use a computer without owning one, and promoted the interactive use of computers and the development of new interactive applications.

In addition to that, several users share the system simultaneously. And this situation can result in various security problems. Two of these problems are (1) taking possession or copying another user’s data and (2) using system resources without proper accounting.

               People could not avoid copying another user’s data but the problem in that situation is that there are times that the shared files is gained, often by devious means, by those who should not have access to them. Another thing is that, one user may use the resources or the copied data but charge expenses to other users. 

 The other dilemma concerning the security problems in multiprogramming and time sharing environment includes the usage of system resources without proper accounting. System resources are the parts within a computer that are available to be used by the operating system and other applications. Examples of these are CPU, amount of memory in use, printer, etc. Improper accounting would cause troubles such as; the printer could mix output by sending data while some other users file is printing.

On the other case, I don’t think that people can ensure the same degree of security in a time-share machine as we have in a dedicated machine. As we all know, a time sharing system or a server provides several people the opportunity to use the system. Technically, even a standard PC is a time-sharing system due to the fact that people can run numerous programs on it at the same time. Meanwhile, dedicated machine is a computer that services one primary function or task.

Since a time-share machine allows multiple users to use the system, there is a high risk on various security problems. However, there would be a possibility that the people can really ensure a security on dedicated machines since it only assist one task. Thus, the users could not manipulate several data.

Operating System Case Study no. 2

A Theory about How a Newspaper Reporter and a Manager in a Supermarket might use a Hand-held Computer in their Work

Hand held computer is a portable computer that is small enough to be held in one’s hand. Although extremely convenient to carry, hand held computers have not replaced notebook computers of their small keyboards and screens. The most popular hand-held computers are those that are specifically designed to provide PIM (personal information manager) functions, such as calendar and address book. And due to the fact that hand-held computers are handy, it would be favorable to those people who are in need of this kind of device.

Newspaper Reporter

A reporter is a type of journalist who researches and presents information in certain types of mass media. Reporters gather their information in a variety of ways, including tips, press releases, sources (those with newsworthy information) and witnessing events. They perform research through interviews, public records, and other sources. However, reporters generally split their time between working in a newsroom and going out to witness events or interview people.

For the reason that reporters are busy in terms of their work, they would need a scheduler for them to cope up with their activities. And now that hand held computers are invented, it would be suitable for them since most PIMs enable people to enter various kinds of textual notes such as reminders, lists, and dates. Furthermore, it is also capable to link these bits of information together in useful ways. Another thing is that, hand held devices have become ruggedized for use in mobile field management situations to record information in the field.

With the uses of the device, it would lessen the burden of the reporters since their activities and events would be organized plus it could support them to be more productive.

Manager in a Supermarket

Aside from having textual notes and can record information, hand held devices are also use to achieve a variety of tasks for increasing efficiency that include digitizing notes, sending and receiving invoices, asset management, recording signatures, managing parts and scanning barcodes. These capabilities are profitable for a manager in a supermarket since the manager can keep automatic track of all inventory that the supermarket has.

Through this, managers in supermarket can analyze sales data and can create better marketing plans. Furthermore, managers can also use the efficiency of hand held computers to organize schedules. Besides, many PIMs also include calendar, and calculator programs.

The adequacy of hand held devices are nevertheless functional, not only for the managers in supermarkets and newspaper reporters, but also to all people who needs help to handle their daily lives appropriately.

Operating System Case Study no. 1

Batch System

GM-NAA I/O

• GM-NAA I/O

 The GM-NAA I/O input/output system of General Motors and North American Aviation was the first operating system for the IBM 704 computer.  It was created in 1956 by Robert L. Patrick of General Motors Research and Owen Mock of North American Aviation. It was based on a system monitor created in 1955 by programmers of General Motors for its IBM 701. The main function of GM-NAA I/O was to automatically execute a new program once the one that was being executed had finished (batch processing). It was formed of shared routines to the programs that provided common access to the input/output devices. Some version of the system was used in about forty 704 installations.

Interactive System

• Unix 

Unix is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs. Unix operating systems are widely used in servers, workstations, and mobile devices. The Unix environment and the client–server program model were essential elements in the development of the Internet and the reshaping of computing as centred in networks rather than in individual computers.

Unix was designed to be portable, multi-tasking and multi-user in a time-sharing configuration. Unix systems are characterized by various concepts: the use of plain text for storing data; a hierarchical file system; treating devices and certain types of inter-process communication(IPC) as files; and the use of a large number of software tools, small programs that can be strung together through a command line interpreterusing pipes, as opposed to using a single monolithic program that includes all of the same functionality. These concepts are collectively known as the Unix philosophy.

Real-time Systems

Unison Operating System

• Unison Operating System

 The Unison Operating System is a real-time operating system (RTOS) optimized for system-on-a-chip (SoC), multi-core and digital signal processor (DSP) systems. It is open source. It offers Linux compatibility while being much smaller than Linux. The current version of Unison is completely POSIX compliant, offering application portability and very low cost hardware implementation options primary for embedded microcontrollers, but also for distributed multi-core and multiprocessor systems like autonomous robots and vehicles. It is so tiny that it takes a minimum of 1K byte to run 2 threads.

Unison was developed as a runtime for powerful real-time embedded heterogeneous multiprocessors which were used for military signal processing. The entire goal of Unison was to provide a software infrastructure that would support the construction of inexpensive, lower power, mobile and portable super computers. Unison successfully met this goal and has been deployed in thousands of systems in the field.

Hybrid Systems

• Linux on ITRON

 The hybrid operating system approach which is to combine a general-purpose operating system with a real-time operating system is a promising approach to satisfy the real-time property, which is usually required or embedded systems. The paper describes a hybrid operating system architecture called "Linux on ITRON," which is a combination of Linux and a real-time kernel based on the μITRON Specification. A problem raised in the design of "Linux on ITRON" and its solutions are also discussed.

Embedded Systems

iOS

• iOS 

 iOS (iPhone OS until June 2010) is Apple's mobile operating system. Developed originally for the iPhone, it has since been shipped on the iPod Touch, iPad and Apple TV as well. Apple does not permit the OS to run on third-party hardware. As of October 20, 2010, Apple's App Store contains more than 300,000 iOS applications, which have collectively been downloaded more than 7.5 billion times. As of May 2010, it had a 15.4% share of the smartphone operating system market in terms of units sold, third behind Symbian and RIM's Blackberry, but accounted for 59% of mobile web consumption (not including the iPad) in North America.

The user interface of iOS is based on the concept of direct manipulation, using multi-touchgestures. Interface control elements consist of sliders, switches, and buttons. The response to user input is immediate and provides a fluid interface. Interaction with the OS includes gestures such as swiping, tapping, pinching, and reverse pinching. Internal accelerometers are used by some applications to respond to shaking the device (one common result is the undo command) or rotating it in three dimensions (one common result is switching from portrait to landscape mode).

iOS is derived from Mac OS X, with which it shares the Darwin foundation, and is therefore aUnix-like operating system by nature.

My first..

I usually thought that having a blog is a tiresome thing to do.
But then, we need to have one for the subject Operating System.
And now, that I really have one, I  find it fun so might as well enjoy it. HAHAHA. >.<