【Fujitsu】 OSII

 OSII was the operating system (hereinafter “OS”) for Fujitsu’s large-scale general-purpose computers FACOM 230-45S and FACOM 230-55, and was announced in August 1968. By adopting a virtual memory management using the paging address mechanism of the hardware, OSII realized multi-program control without dynamic relocation.
 In August 1973, Fujitsu announced OSII/VS, which substantially strengthened OSII as the OS for FACOM 230-38/48/58 and was Fujitsu’s first OS to realize multiple virtual memory control (mentioned below).
 The following describes the brief history of the large general-purpose OSs for the FACOM 230-5 and 8 series, and the features of the OSs.

1. Brief history of large general-purpose OSs for the FACOM 230-5 and 8 series

  OSII was announced as the FACOM 230-45 operating system together with the announcement of FACOM 230-25/35/45 in August 1968. At that time the OS was not given a definite name, so instead the OS was called OS 45 or 45OS as abbreviated name. When the large general-purpose computer FACOM 230-55 was announced in November 1972, the renaming of the FACOM 230-45 operating system as OSII was also announced together with its functional enhancement.

Figure: Configuration of OS-45 (later renamed OSII)

Figure: Configuration of OS-45 (later renamed OSII)

OSII was aimed at realizing a superb price/performance ratio in addition to providing a function for responding to all forms and scales of processing in order to meet the demands of the online computing era. To achieve this goal, Fujitsu developed OSII based on its experience with the earlier-developed OSs MONITOR III, IV and V for FACOM 230-50 and 60, while covering the functions of the OSs BOS and ROS for the company’s medium general-purpose computers FACOM 230-25 and 35. OSII was completed in June 1971.

 OSII/VS, which was announced in August 1973 as the operating system for FACOM 230-38/48/58 with substantially enhanced functions over OSII, such as a virtual memory control function and an online database, was completed in November 1974. OSII/VS enabled its use from the minimum-capacity メmemory of 96K bytes by further modularizing the structure. So FACOM 230-38 was able to provide performance and functions equivalent to those of a large computer with the price of a medium-size computer.
2. Features of OSII

 OSII had the following features:

(1) Supported all forms of processing such as batches, remote batches, database (RAPID)(*)/data communication (SOM/COP)(*) processing
 OSII adopted a further modularized structure that enabled configuration according to the required function and the scale, achieving a remarkably excellent price/performance ratio.
*:RAPID;Retrieval And Production for Integrated Data
SOM;Standard Online Module
COP;online COmmon Package
(2) Adopted a virtual memory management using the page address mechanism of the hardware to achieve multi-program control without dynamic relocation
 FACOM 230-45, 45S and 55 had a page address mechanism that allowed mapping a logical address to a physical address in a 2-KB page unit. The mechanism removed the restriction which was that the physical address of the program and the data had to be continuous area in the memory. Under this mechanism when loading a new program, the only requirement was to prepare total required capacity of the memory even if they were scattered pages. Because the mechanism arranged the scattered physical addresses into a continuous logical address by rewriting the page table for converting the logical address to a physical address. In other words, the OS did not require dynamic relocation, which was formerly practiced as multiprogramming control.
(3) Provided the console functions to increase the operation efficiency of multi-job processing and simplify operation, through various status display functions and a multi-console function based on use of a character display unit
 At that time, multiprogramming function of OS was common, and it had become the important issue to increase its operation efficiency, usability and operability. OSII provided the above console functions, which used simple and powerful operating commands and increased the operability of the OS.
(4) Realized efficient multiprocessor control
 The multiprocessor system of FACOM 230-55 provided a multiprocessor control that increased overall processing capacity in a balanced manner so that jobs were not concentrated on a particular CPU while allowing the two CPUs to operate simultaneously.
(5) Provided SOM (Standard Online Module), which allowed the user to easily realize online processing
 As online support for OSII, Fujitsu provided COP (online COmmon Package), which was intended for large online systems, and SOM, the aim of which was to easily achieve online processing using a standard terminal. SOM had GET/PUT (RECEIVE/SEND) access macros, a tool to call jobs from a terminal (terminal command) and a roll-in/roll-out control function. It was capable of writing a program in COBOL language, and applicable to a broad range of business applications such as inquiry operations, data collection/distribution operations and message exchange operations.
3. Features of OSII/VS

 OSII/VS had the following features:

(1) Achieved 96K bytes as the memory capacity needed for a minimum scale system by further modularizing the structure while maintaining the compatibility with OSII (128K bytes memory was necessary for the minimum scale system)
(2) Fujitsu’s first OS to realize multiple virtual memory control through highly efficient virtual memory control
 OSII, which was the predecessor to OSII/VS, had achieved primary virtualization of the memory resource. However, with OSII, the logical page needed to correspond to the physical page one-to-one. With OSII/VS, Fujitsu eliminated this restriction by using the APA (Advanced Page Address) mechanism of the hardware, and allowed the logical page to dynamically correspond to the physical page, thereby achieving perfect virtualization. This enabled up to 127 virtual memory spaces allocation of each 4 M bytes.
 The OS adopted LRU (Least Recently Used) as the page replacement rule. And there was additional rule, that is, in the event of thrashing, in which page-in/out occurred extremely frequently, the LRU method was switched to a RANDOM method.
(3) Enhanced online support (provision of online database packages INIS and RICS)
 OSII provided online software SOM and COP, and the database management system RAPID, separately. OSII/VS provided INIS and RICS as online database packages. INIS was designed to establish a database centric by integrating SOM and RAPID. RICS aimed at operating a full-scale online database system by integrating COP and RAPID.
INIS:Integrated Information System,RICS:Real time Information Control System
(4) Provided two types of BOS emulators for migration from BOS to OSII/VS (or to OSII)
 ”The integrated emulator BOSEM22 + BOS monitor + a BOS job” was executed on OSII/VS as one job of OSII/VS, and could be processed simultaneously with another job on OSII/VS.
 “The stand-alone emulator BOSEMX + BOS monitor + a BOS job” was executed as a single operation unit. BOSEMX required fewer hardware resources than the integrated type, but it needed to separate the emulation service time zone and the native OS (OSII/VS) service time zone.