Brief History of IBM Mainframe Computers and Computing

When I began my working career in the IT (Information Technology) business in 1968, I first worked in IBM with the computer series S/360 (System 360). IBM named the series as 360 (a complete revolution) as, apart from being in the '60s, they regarded those as their first ever all-rounder general purpose computers. Entered the '70s, I then worked with the successor series S/370 (System 370). Came the '80s. IBM stopped short of producing System 380 series. Instead, they produced the 308x series (3081, 3083 etc) and 3090 series, and I continued to work with those. Further came the '90s, I then worked with the Enterprise System ES/9000. At the turn of the millennium into 2000, IBM came back again to the series S/390 (System 390).
All these were mainframe computers which were huge processor complex running all or most applications in a corporation. The processor complex were huge in the sense of their processing power and also they were big refrigerator-type boxes which needed to stay in large air-conditioned, humidity-controlled computer rooms with raised flooring (to hide the numerous computer cables underneath). Data were stored in numerous fast-spinning disks coupling together in a big disk farm which gave another reason why a large computer room was needed. Usually the computer rooms were behind floor-to-ceiling glass walls as companies wanted to show off to their customers the usage of high technology. The computer rooms were dubbed as 'glass houses' at that time. Processing power of the mainframe computers were measured by MIPS (million instruction per second that the processor could compute). As an indication, a S/360 model 20 in 1965 was at 0.002 MIPS and a S/390 model G6 in 1999 was at 1644 MIPS.
In the '60/70s, computing were essentially done by mainframe computers. Processing power of mainframe computers grew exponentially year after year. However, in the '80/90s, with the advent of high-speed telecommunications and personal computers, computing began to shift from centralizing all processing in one single huge mainframe to a distributed processing environment. Individual applications (e.g. accounting or email etc) would be offloaded to individual mid-range computers with medium-sized processing power like Sun Microsystem or HP (Hewlett Packard). Personal applications (e.g. word processing etc) would be offloaded to personal computers with numerous brands and models. Mainframe computers would no longer grew in power as fast as before. Instead, the mainframe computer, mid-range computers and personal computers were interconnected via advanced telecommunications links to form a computer network to collaboratively perform all necessary processing for a corporation. Computing began to be done under multi-tiered architecture environments. A typical 3-tiered architecture might have a large mainframe computer for corporate computing (running the critical applications like reservations in an airline for the entire corporation), several mid-range computers for departmental computing (running individual applications like Accounting for the Accounts department, Flight Scheduling for the Flight Control Department etc), and numerous personal computers for personal computing (running as individual staff workstations and to access the mainframe or mid-range computers depending on individual staff needs).
In addition to computing internally within a corporation, the '90s saw the evolution of business into the e-business era where corporations connected externally to other companies to perform electronic business-to-business transactions (e.g. to banks or credit card companies or to other enterprises etc). Corporations also had increasing demand for global information access and sharing via the internet (which is a global system of interconnected computer networks using a commonly accepted standard called internet protocol), and increasing demand for internal information access and sharing via the intranet (which is a corporate computer network using the internet protocol technologies for internal usage within the corporation).

Moving into the new millennium 2000, computing continues to evolve in different diversities. We are seeing continuing advancements in computing speed, functionality and accessibility at all levels enabling users to obtain information and knowledge of any sort from anywhere at any time as they desire.