Convergent Technologies Operating System

The Convergent Technologies Operating System, also known under the name of CTOS, BTOS and STARSYS, was a modular, multi- process- based operating system developed by Convergent Technologies.

Convergent Technologies ' first product was the IWS (Integrated Workstation), which sat on the Intel 8086 processor and CTOS implemented as operating system. The successor product NGEN was later taken over by Bosch (Tele Norma) is licensed and marketed.


The CTOS operating system based on a 4- KB - real-time microkernel, this included

  • Multitasking
  • Network connection
  • Several processes and threads
  • Message-Based Inter -process communication

The kernel interpreted the message and forwarded the message to the resource further, which could respond to the message. It did not matter if the response from the local system or a remote system came from. Each CTOS workstation a managed resource table. When receiving a message via the microkernel examined whether this message is a local resource existed, if not, the kernel tried to delegate the message over the network to a server acting as CTOS instance.

Through this system as early as 1986 on the 8086 -based network systems ( RS422/307K baud) could be built, which made it possible, within a " cluster " of up to 16 workstations together on databases (Data Manager) to work Multiplan tables or texts.

It was interesting that this system was initially delivered with the full source code and the user was a complete " Office " package from Data Manager, Multiplan and text processing. Besides Assembler, Basic and Pascal and Fortran and Cobol compilers were available. ISAM and SAM file formats as well as a font designer and 3270, RJE and AT emulators were available as mainframes. The system could communicate over a network module with both TCP / IP networks as well as with SNA networks. It was also the playfulness of users satisfied when needed and have a rat trap game for the text matrix systems and a helicopter simulation game for the graphics systems delivered, as on the other systems still horizontal jumping tennis balls or horizontally flying saucers made ​​by keyboard clicks were.


The hardware of the systems included at the beginning of 8 " - later 5.25" floppy disks and 5 -MB to 20 -MB hard disks ( Bourroughs B20 / 8086 5 MHz 256-640 KB RAM). Later, a modular hardware system ( NS ) has been developed and its hardware components were to assemble with simple lever - clamp connections in a row. With a bus system connected to each other could the desired workstation system from processor (Intel 8088, 80286/80386 ... 5 MHz 128 KB to 512 KB RAM), mono- graphic unit (15 " × 9 × 11Pix/28 80Zeilen ) or color graphics systems with mouse, hard disk (5-100 MB), tape unit, floppy, ISDN box and even a hardware PC emulator ( 80286 ) can be built, the individual components were each exchange and combined. This system design was ahead of its time, but could not prevail against the reduction of the prices and technically simpler competition from Apple, Commodore, Amiga and PC. The operating system was to use, depending on the distributor as a UNIX system, at Bull systems, the operation was extremely simple and pure operated via top-level commands. Furthermore, Bull various office communications programs on offer, word processing, spreadsheet, and advanced connectivity to mainframe Bull and IBM were both X.25 and TCP / IP possible.


Companies which licensed CTOS, were Burroughs ( BTOS ) and Bull Computers ( STARSYS ). The largest licensee was Unisys. In Germany, the hardware of Burroughs ( B20/B21/B22 ) of TELENORMA / Bosch ( NS / TNOS ), MDS Hero ( Mohawk Data Sciences ) and Bull Computers ( Questar 400 series / Q400 / Q410 / Q420 / Q460 ) offered. Convergent Technologies and Unisys merged 1988. 1996 CTOS has been set.

  • Operating system
  • Abbreviation
  • Historic software