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Operating Systems Essay, Research Paper
Operating Systems
An operating system is the program that manages all the application programs in a computer
system. This also includes managing the input and output devices, and assigning system
resources.
Operating systems evolved as the solution to the problems that were evident in early computer
systems, and coincide with the changing computer systems. Three cycles are clear in the
evolution of computers, the mainframe computers, minicomputers and microcomputers, and each
of these stages influenced the development of operating systems.
Now, advances in software and hardware technologies have resulted in an increased demand for
more sophisticated and powerful operating systems, with each new generation able to handle and
perform more complex tasks. The following report examines the development of operating
systems, and how the changing technology shaped the evolution of operating systems.
First Generation Computers (1945-1955).
In the 1940’s enormous machines capable of performing numerical calculations were created.
The machine consisted of vacuum tubes and plugboards, and programming was done purely in
machine code. Programming languages were unheard of during the early part of the period, and
each machine was specifically assembled to carry out a particular calculation.
These early computers had no need for an operating system and were operated directly from the
operator’s console by a computer programmer, who had immediate knowledge of the computers
design.
By the early 1950’s punched cards were introduced, allowing programs to be written and read
directly from the card, instead of using plugboards.
Second Generation Computers (1955-1965).
In the 1950’s, the transistor was introduced, creating a more reliable computer. Computers were
used primarily for scientific and engineering calculations and were programmed mainly in
FORTRAN and assembly language.
As computers became more reliable they also became more business orientated, although they
were still very large and expensive. Because of the expenditure, the productiveness of the system
had to be magnified as to ensure cost effectiveness. Job scheduling and the hiring of computer
operators, ensured that the computer was used effectively and crucial time were not wasted.
Loading the compilers was a time consuming process as each compiler was kept on a magnetic
tape, which had to be manually mounted? This became a problem particularly when there were
multiple jobs to execute written in different languages (mainly in Assembly or Fortran). Each
card and tape had to be individually installed executed then removed for each program. To
combat this problem, the Batch System was developed. This meant that all the jobs were grouped
into batches and read by one computer (usually an IBM 1401) then executed one after the other
on the mainframe computer (usually an IBM 7094), eliminating the need to swap tapes or cards
between programs.
General Motors designed the first operating system called IBM 701. It was called input/output
System, and consisted of a small set of code that provided a common set of procedures to be
used to access the input and output devices. It also allowed each program to access the code
when finished and accepted and loaded the next program. However, there was a need to improve
the sharing of programs, which led to the development of the SOS (Share operating system), in
1959. The SOS provided buffer management and supervision for I/O devices as well as support
for programming in assembly language. Around the same time as SOS was being developed, the
first operating system to support programming in a high-level language was achieved. FMS
(Fortran Monitoring System) incorporated a translator for IBM’s FORTRAN language, which
was widely used as most programs where written in this language.
Third Generation Computers (1965-1980).
In the late 1960’s IBM created the System/360 which was a series of software compatible
computers ranging in different power of performance and price. The machines had the same
architecture and instruction set, which allowed programs written for one machine to be executed
on another. The operating system required to run on this family of computers has to be able to
work on all models, be backward compatible and be able to run on both small and large systems.
The software written to handle these different requirements was OS/360, which consisted of
millions of lines of assembly language written by thousands of different programmers. It also
contained thousands of bugs, but despite this the operating system satisfactory fulfilled the
requirements of most users. A major feature of the new operating system was the ability to
implement multiprogramming. By partitioning the memory into several pieces, programmers
where able to use the CPU more effectively then ever before, as a job could be processed whilst
another was waiting for I/O to finish.
Spooling was another important feature implemented in third generation operating systems.
Spooling (Simultaneous Peripheral Operation On-Line) was is ability to load a new program into
an empty partition of memory when a pervious job had finished. This technique meant that the
IBM 1401 computer was no longer required to read the program from the magnetic tape. Mission
of a job and returning of results had increased. This led designers to the concept of time-sharing,
which involved each user communicating with the computer through their own on-line terminal.
The SPU could only be allocated to 3 terminals, each job held in a partition of memory. Many
time-sharing operating systems were introduced in the 1960’s, including the MULTICS
(Multiplexed Information and Computing Service). Developed by Bell Labs, MULTICS was
written almost completely in high-level language, and is known as the first major operating
system to have done so. MULTICS examined many new concepts including segmented memory,
device independence, hierarchical file system, I/O redirection, a powerful user interface and
protection rings.
The 1960’s also gave rise to the minicomputer, starting with the DEC PDP-1. Minicomputers
presented the market with an affordable alternative to the large batch systems of that time, but
had only a small amount of memory. The early operating system of the minicomputers were
input/output selectors, and provided an interactive user interface for a single user, and ran only
one program at a time.
By the 1970’s, DEC introduced a new family of minicomputers. The PDP-11 series had 3
operating systems available to use on the systems, a simple single user system (RT-11), a time
sharing system (RSTS) and a real-time system (RSX-11).
RSX-11 was the most advanced operating system for the PDP-11 series. It supported a powerful
command language and file system, memory management and multiprogramming a number of
tasks.
Around the same time as DEC were implementing their minicomputers, two researchers, ken
Thomspson and Dennis Richie were developing a new operating system for the DEC PDP-7.
Their aim was to create a new single-user operating, and the first version was officially released
in 1971. This operating system, called UNIX became very popular and is still used widely today.
Fourth Generation Computers (1980-1990)
by the 1980’s, technology had advanced a great deal from the days of the mainframe computers
and vacuum tubes. With the introduction of large-scale Integration circuits (LSI) and silicon
chips consisting of thousands of transistors, computers reached a new level.
Microcomputers, which were physically much like the minicomputers of the third generation,
however they were much cheaper enabling individuals to now use them, not just large
company’s and universities. These personal computers and required an operating system that was
user friendly so that people with little computer knowledge was able to use it. In 1981, IBM was
releasing a 16-bit personal computer, and required a more powerful operating system then the
ones available at the time, so they turned to Microsoft to deliver it. The software, called Micro
Soft Disk Operating System (MS-DOS) became the standard operating system for most personal
computers of that era.
In the mid-1980’s, networks of personal computers had increased a great deal, requiring a new
type of operating system. The OS had to be able to manage remote and local hardware and
software, file sharing and protection, among other things. Two types of systems were introduced,
the network operating system in which users can copy from one station to another, and the
distributed operating system, in which the computer appears to be a uni-processor system, even
though it is actually running programs and storing files in a remote location. One of the best
known network operating system for a distributed network is the Network File System (NFS),
which was originally designed by Sun Microsystems, for use on UNIX based machines. An
important feature of the NFS is its ability to support different type of computers. This allowed a
machine running NFS to communicate with an IBM compatible machine running MS-DOS,
which was an important addition to networking computing.
In 1983, Microsoft Corporation introduced the MSX-DOS, an operating system for MSX
microcomputers that can run 8-bit Microsoft software including the languages BASIC, COBOL80, and FORTRAN-80, and Multiplan.
1984 saw the release of the Apple Macintosh, a low-cost workstation, which evolved from early
Alto computer designs. The Macintosh provided advanced graphics and high performance for its
size and cost. As the Macintosh was not compatible with other systems, it required its own
operating system, which is how the Apple operating system was established. MIMIX, based on
the UNIX design was also a popular choice for the Macintosh.
As computer processors got faster, operating systems also had to improve in order to take
advantage of this progression. Microsoft released version 2 of MS-DOS, which adopted the
many features that made UNIX so popular, although MS-DOS was designed to be smaller then,
but was not as large as the UNIX operating system making it ideal for personal computers.
Modern Operating Systems
The past 9 years have seen many advances in computers and their operating systems. Processors
continue to increase in speed, each requiring an operating system to handle the new
developments. Microsoft Corporation has dominated the IBM compatible world, Windows being
the standard operating system for majority of personal computers.
Now as computing and information technology becomes more towards the Internet and virtual
computing, so too must the operating systems.
In 1992, Microsoft for Workgroups 3.1 was introduced, extending on from the previous versions.
It allowed the sending of electronic mail, and provided advanced networking capabilities to be
used as a client on an existing local area network. This was only the one stage in the vast
evolution of the worlds most popular operating system, with the most recent being Windows NT
and Windows 98, the latter being a fully Internet integrated operating system. Windows,
however is not the only operating system in use today? Other’s such as UNIX, Apple Operating
System and OS/Warp have also had an impact, each new version more advanced, and more user
friendly then the la