-
Period: to
1940s
was a time of vacuum tube
technology and computers the size of classrooms. Each computer was unique in
structure and purpose. There was little need for standard operating system software
because each computer’s use was restricted to a few professionals working on
mathematical, scien- tific, or military applications, all of whom were familiar with the
idiosyncrasies of their hardware. -
Period: to
1950
were developed to meet the needs of
new markets—government and business researchers. The business environment
placed much more importance on the cost effectiveness of the system. Computers
were still very expensive, especially when compared to other office equipment (the
IBM 7094 was priced at $200,000). Therefore, throughput had to be maximized to
make such an investment worthwhile for business use, which meant dramatically
increasing the usage of the system -
1960s
They were designed with
faster CPUs, but their speed still caused problems when they interacted with printers
and other I/O devices that ran at slower speeds. The solution was multiprogramming,
which introduced the concept of loading many programs at one time and sharing
the attention of a single CPU. -
1970s
The first multiprogramming systems allowed each program to be serviced in turn,
one after another. The most common mechanism for implementing
multiprogramming was the introduction of the concept of the interrupt, whereby
the CPU was notified of events needing operating system services. For example,
when a program issued a print command (called an input/output command or an
I/O command), it generated an interrupt requesting the services of the I/O processor -
1980s
Development in the 1980s dramatically improved the cost/performance ratio of
com- puter components. Hardware was more flexible, with logical functions built on
easily replaceable circuit boards. And because it was less costly to create these
circuit boards, more operating system functions were made part of the hardware
itself, giving rise to a new concept—firmwar -
1990s
The overwhelming demand for Internet capability in the mid-1990s sparked the proliferation of networking capability. The World Wide Web, conceived in a paper,
worldwide, not just the researchers who had come to depend on it for global
commu- nications. Web accessibility and e-mail became standard features of
almost every oper- ating system. However, increased networking also sparked
increased demand for tighter security to protect hardware and software. -
2000s
The new century emphasized the need for operating systems to offer improved
flexibility, reliability, and speed. To meet the need for computers that could
accommo- date multiple operating systems running at the same time and sharing
resources, the concept of virtual machines.
Virtualization is the creation of partitions on a single server, with each partition
supporting a different operating system.
