【NTT】 DIPS-103-10OS - Operating System for Time-Sharing Systems

The scientific and engineering computing system DEMOS (Dendenkosha Multi-access Online System) started public service in March 1971, using commercially obtainable computer hardware. Subsequently, a series of similar time-sharing system (TSS) services were initiated by some vendors. To maintain the superiority of the TSS service offered by Nippon Telegraph and Telephone Public Corporation (now called Nippon Telegraph and Telephone Corporation) over the competition, the company placed high priority on constant improvement of the system while making the TSS service easier to use for customers. Accordingly, a development project started to renew the system for the TSS service.

The DEMOS-E service (commencing November 1972) was started by using the originally designed DIPS-1 hardware and substantially expanding the contents of the scientific and engineering computing system DEMOS and improving its functions; the core of the system was the DIPS-103-10 Operating System. Based on the 103 operating system, a multipurpose OS on DIPS-1, this OS was designed to support specific functions of the DEMOS-E service.

The basic concepts of the 103-10OS itself are the same as those of the 103OS. This OS has the following functions.

(1) Duplex system operation functions
(2)Interactive processing (TSS processing) and batch processing (remote batch and local batch processing) functions support
(3) File-sharing functions in job processing

With this OS, two methods were realized for disk space management: for the TSS service as well as for the system volume, a general-use volume file management method with paged blocks; and for real-time processing, private volume disk management using Volume Table of Contents (VTOC). Interactive processing dedicated for TSS was achieved as the basic functions of 103-10OS, which were later separated and packaged. The 103-10OS was then reorganized to contain only the functions that were essential for the operating system.