GCOS - SpeedyLook encyclopedia

GCOS /jee ' kohs/( G eneral C omprehensive O perating S ystem) is a family of Operating system directed Mainframe S.
La first version was developed by General Electric starting from 1962; named historically GECOS (the G eneral E lectric C omprehensive O perating S upervisor).

There remains still nowadays used on large systems. The programs on this operating system are generally written in COBOL, FORTRAN (even ALGOL), and now Java.

Structure system and concepts

GCOS uses the concept of process to describe sequences of instructions which act on a whole of data and which are carried out on a processor. It also has the concept of Multitâche. Moreover, there exists a concept of group of process , entity containing several processes charged and scheduled simultaneously. GCOS also provides semaphores to synchronize processes between them or with the material.

Each process has its own space of addressing, on which the rights of access are a combination of elementary rights ( reading , writing , execution ). The space of addressing is segmented, which allows the division of data between process . The management of the privileges is based on the rings : each process is associated with a ring , plus the level of the ring is low, plus the process has privileges.

The operating system can manage the computers multiprocessors (SMP). It is based on a Micro-noyau established on the Firmware of the machine. It can also function in modes of emulation with very weak lose speeds.

History

The operating system GECOS-II was developed by General Electric for the GE-635, a machine 36 bits, of 1962 with 1964. Contrary to the rumor, GECOS is not a copy of System/360 (rumor unfortunately taken again by the " Jargon file"), indeed the architecture of the GE-635 was very different from that of the IBM 360, and GECOS was much more ambitious than DOS/360. One of the outstanding characteristics of the second generation of this Operating system was the support of the Temps divided (Time-sharing, " TSS") as well as Batch processing (" batch").

After the repurchase of the division of the Computer S of General Electric by Honeywell, GECOS-III was renamed GCOS-3, and the famous line of machines H-6000. Later, the marketing of Honeywell created a " Series 60" , and famous H-6000 in Level-66. Honeywell, with its European associate CII-Honeywell Bull, also decided to launch a new line of products " Level 64" , which became then the DPS-7. The name " GCOS" then extended to all the lines of products marketed by Honeywell and to GCOS-64, a completely different operating system 32 bits, largely inspired by Multics develops in parallel by Honeywell and Honeywell-Bull in France and with Boston. GCOS-62, another system 32 bits bottom-of-the-range was conceived in Italy. GCOS 61 was a new version of a small system carried out in France, and new line DPS-6 of minicomputers 16 bits from Massachusetts took name GCOS-6.

Another name change in the lines of products took place in 1979, the Level-6 becoming the DPS-6 famous Level-61 DPS-4, the Level-64 renamed in DPS-7, and the Level-66 from now on called DPS-8. The Operating systems kept trade name GCOS, with the introduction of GCOS 6, GCOS 4, GCOS 7 and GCOS 8. All these changes caused a certain confusion among customers, because line GCOS of origin, which was called GCOS-III (or GCOS-3) had suddenly become GCOS 8. GCOS-3 was supported and maintained for several years after these advertisements.

GCOS-3 (and then GCOS-7 and GCOS-8) had a good basic Management system of data network (CODASYL) called IDS (Integrated Data Blind). IDS was the model for IDMS, which was more success. Version IDS/2 is still used to date.

Several compromise Moniteurs was conceived for GCOS-3 and GCOS-8. A first version of monitor for GCOS-3 supposed, as in Unix, new a process is launched for each transaction of the Database. The customers of IBM wanted a model more effective where light processes (threads) multiplexed await messages and share resources. These characteristics were carried out in the form of subsystems.

GCOS-3 soon had a true compromise monitor named TDS (Transaction Driven System), which was primarily a development of Honeywell. TDS then evolved/moved in DMIV-TP then in TP8 on GCOS-8. TDS and its successors were the business successes and taken market shares on CICS (of IBM) whose architecture was similar. A similar product, also called TDS, was developed for GCOS-7.

GCOS-6 and GCOS-4 (ex GCOS-62) were exceeded by minicomputers containing Motorola 68000 and of PowerPC under Unix, and the lines of products were stopped. However GCOS-6 turned in a emulator functioning on AIX. Range DPS-7, with GCOS 7, continued to evolve/move with the DPS-7000.

At the end of the Years 1980, Honeywell sold its computing activity with a joint venture to which NEC and Bull belongbelonged, and to which Honeywell took share during a time. In a few years, Bull took the head of this company. NEC provided several generations of material " large-système" in the high-end, which turned at the same time with GCOS 8 and their own system ACOS -4. Bull used denomination DPS-9000 for its whole line of great systems GCOS-8, with models designed by Bull and NEC.

At the end of the Years 1990 and at the beginning of the Years 2000, Bull wanted to center its development on only one type of material containing Integrated circuits standard Intel, but with " bonus" Bull. On this platform Novascale (based on the processors Itanium 2) turn Windows and Linux in native mode. Who more is, of the emulators (Instruction Set Simulator) of DPS-7000 and DPS-9000 allow to make turn GCOS7 and GCOS8 on this platform. Bull continuous to invest in the development and the support of GCOS7 and GCOS8, and still has customers in many countries in the world.

Anecdote

Some of the first Unix systems of the Bell Labs used machines under GCOS like Spool S of impression and various services. The element added to the file /etc/passwd to store the information of identity GCOS was baptized “field GECOS” ( GECOS field ) and always exists in API Unix, named pw_gecos, containing the complete name of the user and other information of primarily human use.

See too

External bonds

Of GECOS with GCOS8 - history of the GCOS.
http://www.bull.com/servers/gcos8/ - products GCOS8 of the Bull group.

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