Mainframe computing

Mainframe computing was developed at a time when computational power was an expensive and scarce resource. In order to use the expensive computer technologies efficiently, organizations had to share their resources. Many of computerized such as invoicing, purchasing, payroll, accounting and so on, involved the organization 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

• for security: the protection of data from outside or unauthorized access
• for integrity: the guarantee that the data is not corrupted and that repeatability is achievable using the same applications and data
• for system availability: centralized facilities can be operated by teams in shifts 24 hours a day, maximizing the investment in IT equipment and allowing large data processing activities to be carried out efficiently
• for data sharing: data input or created in one part of the organization becomes available to other parts
• for applications: many modern applications, such as personnel management systems, require access to a shared pool of resources.

Nowadays, 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 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. Nowadays, 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.

The mainframe is the data and application repository for most organizations. It is also the hub for most online business activities. It is believed that mainframes still house 90 per cent of the data major organizations 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. The level of mainframe sophistication has grown over the more than thirty years of its evolution; organizations still recognize its advantages in terms of performance, reliability and security.