Система разделения времени Dartmouth: История и развитие

Discontinued operating system

The Dartmouth Time Sharing System (DTSS) is a discontinued operating system first developed at Dartmouth College between 1963 and 1964. It was the first successful large scale time sharing system to be implemented, and was also the system for which the BASIC language was developed. DTSS was developed continually over the next decade, reimplemented on several generations of computers, and finally shut down in 1999. General Electric developed a similar system based on an interim version of DTSS, which they referred to as Mark II. Mark II and the further developed Mark III was widely used on their GE 600 series mainframe computers and formed the basis for their online services. These were the largest such services in the world for a time, eventually emerging as the consumer oriented GEnie online service.

From 1966 to 1968, DTSS was reimplemented on the GE 635, still using the DATANET 30 for terminal control. The GE 635 system was delivered in November 1966. By October 1967, it was providing a service based on Phase I software, jointly developed by Dartmouth and GE, which GE subsequently marketed as the GE Mark II system. The experiences with the 265 system. The published concepts of the Multics system. A realization of the limitations of the capabilities of a part time staff of Dartmouth students and faculty members. This new version was completely different internally from the earlier DTSS, but provided a near identical user interface to enable a smooth transition for users and course materials. The 635 version provided interactive time sharing to up to nearly 300 simultaneous users in the 1970s, a very large number at the time, and operated at eleven commercial and academic sites in the US, Canada and Europe. As it evolved in the 1970s, later versions moved to Honeywell 6000 series mainframes (1973) and Honeywell 716 communication processors (1974). In 1976 the GE 635 system was replaced by a Honeywell 66/40A computer. It remained in operation until the end of 1999. DTSS, version 2, included a novel form of inter process communication called "communication files". They significantly antedated Unix pipes, as design documents put their conceptual origin sometime in 1967, and were described briefly in a 1969 conference:
A communications file allows two jobs to interact directly without the use of secondary storage. A communications file has one end in each of two jobs. It is the software analog of a channel to channel adaptor. This structure allows job to job interactions using the same procedures as for more conventional files. The two ends are labeled master end and slave end. A job at the slave end of a communications file cannot easily distinguish this file from a conventional file. Since a job at the master end of a communications file can control and monitor all data transmitted on that file, a master end job can simulate a data file, thereby providing a useful debugging aid and also providing a convenient mechanism for interfacing running jobs to unexpected data structures. A notable application of communication files was in support of multi user conferences, which behaved somewhat like conference phone calls, and were implemented entirely as user space application programs.

As mentioned above, Hanover High School was connected to DTSS from the system's beginning. Over the next decade, many other high schools and colleges were connected to DTSS via the Kiewit Network, named for Peter Kiewit, donor of funds for the Kiewit Computation Center that housed the DTSS computers and staff. These schools connected to DTSS via one or more teletypes, modems, and dial up telephone lines. Dartmouth students had free, unlimited access to DTSS, but high school students had quotas of 40 to 72 hours of terminal access each week, and college users paid for computer use. Dartmouth ran active programs to engage and train high school teachers in using computation within their courses. By 1967, the following high schools had joined the Kiewit Network: Hanover High School, The Holderness School, Mascoma Valley Regional High School, Kimball Union Academy, Mount Hermon School, Phillips Andover Academy, Phillips Exeter Academy, St. Paul's School, and Vermont Academy. This group expanded in the Dartmouth Secondary School Project, funded by the NSF during 1967–1968, which added the following New England high schools: Cape Elizabeth High School, Concord High School, Hartford High School (Vermont), Keene High School, Lebanon High School, Loomis School, Manchester Central High School, Rutland High School, St. Johnsbury Academy, South Portland High School, and Timberlane High School. From 1968 to 1970, Dartmouth added a number of colleges to the Kiewit Network via its Regional College Consortium. They included: Bates College, Berkshire Community College, Bowdoin College, Colby Junior College, Middlebury College, Mount Holyoke College, New England College, Norwich University, the University of Vermont, and Vermont Technical College. By 1971, the Kiewit Network connected 30 high schools and 20 colleges in New England, New York, and New Jersey. At that time, DTSS was supporting over 30,000 users, of which only 3,000 were at Dartmouth College.

In 2000, a project to recreate the DTSS system on a simulator was undertaken and as a result DTSS is now available for Microsoft Windows systems and for the Apple Macintosh computer.