Time-sharing

One big computer can work for many people. It gives each person a tiny bit of time. It switches so fast it feels like it is just for you.

Long ago, computers were very big and slow. They were also very expensive. One machine might cost two million dollars!

In the past, one person used one machine. It could take days to get work done. This was because the machines were not shared.

Time-sharing changed everything. It lets many users talk to one computer at once. This makes using computers much cheaper.

Today, we still use this idea. Many people share big groups of computers on the internet.

A computer can do many things at once. This is called time-sharing. In this way, one big computer serves many people. The computer gives each person a tiny slice of time. It switches between users very quickly. This makes it feel like the computer is only for you.

In the early days, computers were very different. They were slow and cost millions of dollars. One machine might cost $2 million! Most people could not own one. Instead, they used batch processing. This meant they gave a list of tasks to a team. The team ran the tasks later. A person might wait days to see their results.

Time-sharing changed this. It let people talk to the computer right away. This made computing much cheaper for schools and companies. In the 1960s, new systems like CTSS were made. CTSS stands for Compatible Time-Sharing System. It was a tool for writing software. Later, personal computers became cheap. This meant one person could have their own machine. Today, we use this idea on the Internet. Many people share big groups of computers at once.

Computers can do many things at the same time. This is called time-sharing. It is a way to share one big computer resource among many tasks or people. The computer gives each person a very small slice of processing time. It switches between these tasks so quickly that it creates an illusion. It feels like the computer is working for everyone at once.

This method allows one person to do many tasks. It also lets many different people use the same machine. This makes using computers much more efficient for everyone.

In the past, computers worked in a different way called batch processing. These early machines were very slow and very expensive. An operator had to enter programs one by one using switches. You might have to wait many days to see your results. To fix this, new software like IBSYS was made in 1960. This software helped by queuing up programs to run. This reduced the "dead periods" when the computer was doing nothing. Programmers would write their work on paper tape or cards first. Then, an operations team would schedule the work to run later.

Many smart people helped develop the idea of time-sharing. Robert Dodds described a similar idea in a letter in 1949. Later, John Backus spoke about it at MIT in 1954. In 1957, Bob Bemer suggested a computer utility. He thought computers could work like electricity companies. He said power could be sent to many users.

Christopher Strachey filed a patent for time-sharing in 1959. He also gave a famous paper about it in Paris. This paper was later called the first paper on time-shared computers. These early ideas changed how we think about machines.

One of the first big systems was the Compatible Time-Sharing System. This was called CTSS for short. John McCarthy started the idea at MIT in 1959. Fernando J. Corbató led the team that built it. They tested a prototype by November 1961. IBM even loaned special machines like the IBM 704 to MIT. These machines helped people develop new software. Other systems like the BBN Time-Sharing System started in 1962. The Dartmouth Time-Sharing System began its service in March 1964. These systems proved that sharing a computer could really work.

Time-sharing connects to how we use the Internet today. In the 1980s, personal computers became cheap enough for one person to own. This meant people did not always have to share. However, the main idea of time-sharing is still very popular.

Today, huge server farms host thousands of customers at once. These big computers share their resources among many users. Web sites work in bursts of activity. This allows many people to use the same service without waiting. The old idea of sharing time is still part of our digital world.

Time-sharing is a method in computing where a single resource is shared among many tasks or users. It works by giving each task or user a very small slice of processing time. The computer switches between these tasks so rapidly that it creates an illusion. To the user, it feels as if the computer is executing all tasks simultaneously. This technology enables multitasking for one person or allows many people to use one machine at once.

By allowing concurrent interaction, time-sharing dramatically lowered the cost of computing. It meant people and organizations could use powerful computers without needing to own one.

Before time-sharing, computers used a method called batch processing. Early computers were extremely expensive and very slow. Operators had to manually enter programs using control panels and switches. These programs often took hours to run. Later, batch operating systems like IBSYS, released in 1960, helped by queuing programs to reduce "dead periods." Even then, the process was slow. Programmers wrote code "offline" on paper tape or cards. They then gave these to an operations team to schedule. A programmer might wait days to receive their printed output. This made interactive development very difficult and expensive for most people.

The concept of sharing computing power evolved through several key ideas. In 1949, Robert Dodds described a form of multiprogramming in a letter. In 1954, John Backus discussed the concept at MIT. By 1957, Bob Bemer suggested that computers could act like a utility. He imagined providing computing power to many users just like electricity companies provide power.

In 1958, W. F. Bauer described "parallel systems" that allowed large components to be shared. Christopher Strachey then filed a patent for time-sharing in the United Kingdom in 1959. His paper in Paris was later credited as the first paper on time-shared computers.

After 1960, the meaning of time-sharing shifted toward interactive use. The Compatible Time-Sharing System, or CTSS, was a major milestone. John McCarthy initiated the idea at MIT in 1959. Fernando J. Corbató led the development of the system. A prototype was tested by November 1961. IBM supported this work by loaning mainframes like the IBM 704 and 709 series to MIT. There were specific rules for this loan. MIT could not charge for CTSS use. They could only use the machines for eight hours a day. Another eight hours were reserved for other colleges. IBM used the machines for the remaining eight hours.

Other important systems emerged during this era of discovery. The BBN Time-Sharing System began operation and was demonstrated in 1962. JOSS started its service in January 1964. The Dartmouth Time-Sharing System, or DTSS, began in March 1964. DTSS was quite efficient at handling many people. It supported more than 100 simultaneous users. While some jobs took ten seconds or more, 78% of jobs needed one second or less. About 75% of its 3,197 users used their terminals for 30 minutes or less. These numbers show how effectively the system managed its resources.

In the 1960s and 1970s, many companies became service bureaus. They provided time-sharing as a professional business. Users connected via modems that moved characters at speeds between 10 and 120 per second. They were charged for terminal rent, connection time, CPU time, and disk storage.

Common systems included the PDP-10 and the IBM 360. By 1968, thirty-two service bureaus served the U.S. National Institutes of Health alone. By 1975, Prime Computer's president noted that time-sharing was the biggest end-user market. This era saw many companies like Tymshare and National CSS thrive.

The rise of the personal computer changed the industry. In the early 1980s, microprocessors became cheap enough for individuals to own. A single person could have all the CPU time for themselves. This caused the traditional time-sharing business to decline. However, the core concept has returned through the Internet. Today, expensive server farms host thousands of customers. These servers share common resources among many users at once. Web sites operate in bursts of activity, much like the old systems. This allows modern computing to remain efficient and highly accessible.