Page 82 - DMGT505_MANAGEMENT_INFORMATION_SYSTEM

Unit 5: Business Hardware Software and IT Infrastructure

Mainframe computers eventually became powerful enough to support thousands of online Notes
remote terminals connected to a centralized mainframe using proprietary communication
protocols and proprietary data lines. The first airline reservation systems appeared in 1959 and
became the prototypical online, real-time interactive computing system that could scale to the
size of an entire nation.
IBM dominated mainframe computing from 1965 onward and still dominates this $27 billion
global market in 2004. Today IBM mainframe systems can work with a wide variety of different
manufacturers’ computers and multiple operating systems on client/server networks and
networks based on Internet technology standards.

The mainframe era was a period of highly centralized computing under the control of professional
programmers and systems operators (usually in a corporate data center), with most elements of
infrastructure provided by a single vendor, the manufacturer of the hardware and the software.
This pattern began to change with the introduction of minicomputers produced by Digital
Equipment Corporation (DEC) in 1965. DEC minicomputers (PDP-11 and later the VAX machines)
offered powerful machines at far lower prices than IBM mainframes, making possible
decentralized computing, customized to the specific needs of individual departments or business
units rather than time sharing on a single huge mainframe.

5.2.3 Personal Computer Era (1981 to Present)

Although the first truly personal computers (PCs) appeared in the 1970s (the Xerox Alto, MIT’s
Altair, and the Apple I and II, to name a few), these machines had only limited distribution to
computer enthusiasts. The appearance of the IBM PC in 1981 is usually credited as the beginning
of the PC era because this machine was the first to become widely adopted in American businesses.
At first using the DOS operating system, a text-based command language, and later the Microsoft
Windows operating system, the Wintel PC computer (Windows operating system software on
a computer with an Intel microprocessor) became the standard desktop personal computer.
Today, 95 percent of the world’s estimated 1 billion computers use the Wintel standard.
Proliferation of PCs in the 1980s and early 1990s launched a spate of personal desktop productivity
software tools word processors, spreadsheets, electronic presentation software, and small data
management programs that were very valuable to both home and corporate users. These PCs
were standalone systems until PC operating system software in the 1990s made it possible to
link them into networks.

5.2.4 Client/Server Era (1983 to Present)

Here, computer processing work is split between these two types of machines. The client is the
user point of entry, whereas the server provides communication among the clients, processes
and stores shared data, serves up Web pages, or manages network activities. The term server
refers to both the software application and the physical computer on which the network software
runs. The server could be a mainframe, but today server computers typically are more powerful
versions of personal computers, based on inexpensive Intel chips and often using multiple
processors in a single computer box.
The simplest client/server network consists of a client computer networked to a server computer,
with processing split between the two types of machines. This is called a two-tiered client/
server architecture. Whereas simple client/server networks can be found in small businesses,
most corporations have more complex, multitiered (often called N-tier) client/server architectures
in which the work of the entire network is balanced over several different levels of servers,
depending on the kind of service being requested (see Figure 5.2).

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