Software Requirements Technical Implementation

Content Description of the main functions of an operating system including: interpreting user commands file management memory management input/output management resource allocation Description and comparisons of proprietary v open source software licenses. Understand the benefits of portability for computer programs and information systems. Description and exemplification of current trends in operating system design. Description and exemplification of the appropriate type of software required for a specific information system including: type of application operating system

Operating systems Make a list of the operating systems you know of -

Operating system An operating system is a program that provides common services for computer programs to allow them to run correctly. Without the operating system, all other programs would not be able to run, nor would any of the hardware we use with a computer.

Types of operating systems ROM-based operating systems Used by some mobile phones and tablet computers The entire operating system is held on a ROM chip and is available immediately on startup. Disk based operating system Used by some servers, desktops and laptops Examples - Windows , MacOs & Linux The operating systems must be loaded into main memory by a small program called the bootstrap loader when the device is switched on.

Main Functions of an operating System

Operating System functions – interpreting user commands When a user presses a keyboard key, touches a touchscreen or uses a mouse, this function will make sure that the system responds as the user expects.

Operating System functions – file management The OS ensures that there is sufficient space in main memory to load a file from hard disk into main memory and deals with requests to save to backing storage. File management systems will also retain information on file permissions, so as to either allow or block access to files in line with the access rights set by a user.

Operating System functions – memory management If a number of applications are open, the OS manages the sharing of internal memory among those applications. Allocating and de-allocating addresses in RAM is an important aspect of memory management and will happen thousands of times per second.

Operating System functions – input/output management Handles input to and output from attached hardware devices – keyboard, mouse, monitor, hard disks, and printers. Ensuring that device drivers are present and up to date. A device driver is a piece of software that allows the processor and device to communicate with each other.

Operating System functions – resource allocation Resource allocation is the term used to describe the combination of managing processes and memory management to ensure that applications have enough processor time and can be allocated sufficient space in RAM as necessary.

Operating systems – Licensing A licence means that you have permission to have a copy of the operating system and you are using it with the manufacturer's permission. It is against the law to use software without a licence . Write the law below. A licence may ask you to agree to certain terms before you are allowed to use the software. There are many different kinds of licence available. Single licence. Multiple licences, meaning that the program can be installed on several computers. Site licence means that all the computers within that organisation can have permission to use the software.

Proprietary vs Open Source software Proprietary software is also known as closed source. This means that the software is licenced to only be used under certain conditions and is not able to be shared, copied, redistributed, modified or reverse engineered. The source code for proprietary software would not normally be made available. Commercial software is software that is sold for a profit and can be proprietary. Proprietary software is software that is written by a closed development team who will maintain it. The key is that the author(s) retain full copyright of proprietary software and keep the source code private. The use of proprietary software is often limited by the owner in an attempt to prevent it being passed around. The owner of proprietary software may use technical measures, such as activation keys or product keys to restrict use.

Proprietary vs Open Source software Open source software is software that has its source code available. The licence allows the user to look at the code, make changes to the code and to distribute the code as they choose. Often open source software is developed in the public domain and is developed collaboratively, by a group of users.

Freeware and Shareware Freeware - It is a common misconception that freeware programs are not proprietary. However, if the source code to these applications is not able to be modified, then they are proprietary. Shareware is actually proprietary software that is made available to users at no cost under strict conditions. For example, shareware may have limited functionality relative to the commercial version of the same software, or the license for the software may expire after a certain trial period. The rationale behind shareware is to give potential users the chance to evaluate the software before investing in a license fee. Trial versions of commercial software also fall under the shareware category.

Make a list of Proprietary software

Make a list of Open source software

Proprietary vs Open Source Advantages of proprietary software You will be able to take advantage of the software company's customer service department for troubleshooting and setup purposes. Software is often very high quality as it has been developed by professional teams. Disadvantages of proprietary software You will usually have to pay for the software as the company that produced it will be trying to make a profit. The software will not be adaptable, you cannot change it to meet your individual needs.

Proprietary vs Open Source Advantages of open source software Is free to use, distribute, and change. It has lower costs, and in most cases this is only a fraction of the cost of their proprietary counterparts. It is more secure as the code is accessible to everyone. Anyone can fix bugs as they are found, and users do not have to wait for the next release. It not dependent on the company or author that originally created it. Even if the company fails, the code continues to exist and be developed by its users. New, different versions can be separately developed ('forked') alongside the original code to meet different needs. It uses open standards accessible to everyone; it does not have the problem of incompatible formats that exist in proprietary software. Companies using open-source software do not have to think about complex licencing models and do not need anti-piracy measures like product activation.

Operating systems – Proprietary vs Open Source Disadvantages of open source software It may not always be straightforward to use. Open source operating systems like Linux cannot be learned in a day. They require effort and possibly training from your side before you are able to master them. There is a shortage of applications that run both on open source and proprietary Operating Systems; therefore, switching to an open source platform involves a compatibility analysis of all the other software used that run on proprietary platforms. (For example, much of Adobe's design software is not available on Linux).

Operating systems – Portability A program is said to be portable if it can run on a computer, other than the one it was designed for, with little or no change. For example, can a program be taken from a mac desktop computer and run on a windows laptop? Developers and manufacturers will be able to sell more products if their software is able to be transferred from one type of computer platform to another. Truly cross-platform software is rare. Often, manufacturers will make changes to cope with different platforms or operating systems.

Current Trends in operating Systems Moving from operating systems that are controlled by a keyboard and mouse to touchscreen interfaces. Use of Open source operating systems such as Linux. Desktop and mobile operating systems are increasingly becoming more integrated with distributed system frameworks that control resources in the cloud, eg Office 365, Andriod OS is based around Linux. The idea of establishing browser-only operating systems has been actively picked up recently. Google’s Chrome OS is the most obvious example.