This lesson examines three computer environments: mainframe computing, networks (such as Intranets), and the Internet.
It introduces key concepts related to how mainframes, networks and the Internet work.
Please remember, this lesson is not intended to provide a comprehensive explanation of the technical details of mainframe computing, networks and the Internet. Information is provided in order to introduce you to key concepts and provide an overview of these computing environments.
MAINFRAME COMPUTING
Mainframe computing developed at a time when computational power was an expensive and scarce resource. In order to use the expensive computer technologies efficiently, organisations had to share their resources. Many of computerised applications, such as invoicing, purchasing, payroll, accounting and so on, involved the organisation as a whole.
If the original reasons for the mainframe computing model were cost and scarcity of resources, the current reasons for sharing computer power are
• security: the protection of data from outside or unauthorised access
• integrity: the guarantee that the data is not corrupted and that repeatability is achievable using the same applications and data
• system availability: centralised facilities can be operated by teams in shifts 24 hours a day, maximising the investment in IT equipment and allowing large data processing activities to be carried out efficiently
• data sharing: data input or created in one part of the organisation becomes available to other parts
• applications: many modern applications, such as personnel management systems, require access to a shared pool of resources.
Today, mainframe computing is no longer an expensive resource; sharing is still a cost-effective means of providing computational power. Recent studies have shown that on a per-user basis, mainframe computing provides the least expensive form of computing.
A mainframe environment involves not just the hardware. The security, integrity and availability of the mainframe system can only be achieved if the computer centre is staffed by people with the necessary skills, operated according to a set of practices and managed with the discipline (that is, the processes and procedures) that ensures the appropriate levels of security, integrity and availability.
This is the ‘mainframe environment’.
In a mainframe environment, many people share access to a mainframe computer.
A large central processor is kept in a purpose-built computer centre staffed by personnel responsible for maintaining it. Individuals in the organisation access the mainframe computer through terminals on their desktops in order to share common organisational resources, such as software programs or electronic data. As we use the term today, a mainframe is actually identified more by the ‘environment’ in which the mainframe is operated. In other words, the physical environment: the controlled temperature and humidity and the physical security of having the mainframe behind locked doors.
Mainframe computers are used as tools to support a given ‘business’ application such as
• processing applications for licences
• processing government payroll information
• processing financial accounts
• processing environmental resource information.
In all of these applications, the common denominator is the work process and the rules for undertaking the process. Everyone is undertaking a part of the whole work process and everyone must complete his or her work in accordance with the procedures required to make sure the job is done satisfactorily and the data are complete and consistent.
For example, if ten people are responsible for managing government payroll, each will have a separate responsibility. They will all have access to the same database through the mainframe computer, and each person must complete his or her task adequately before the ‘job’ can be considered complete.
The automation of a given work process, such as processing government payroll information, is often viewed as an information system.
Information system: The combination of information, technology, processes and people brought together to support a given business objective
The mainframe is the data and application repository for most organisations. It is also the hub for most online business activities. It is believed that mainframes still house 90 per cent of the data major organisations rely on to conduct their business. Despite claims that mainframe technology is dying out, sales of mainframe hardware and software remain steady.
The term ‘mainframe’ has always had the image of being something large in size. Yet, however big the early ‘room-filling’ mainframes were, today’s modern versions are no bigger than the size of a household refrigerator.
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