【Fujitsu】 MONITOR V

 MONITOR V was the operating system (hereinafter “OS”) for Fujitsu’s large general-purpose computer FACOM 230-60. Its batch processing function was completed in December 1968 and its TSS (Time Sharing System) function in December 1970. Subsequently, MONITOR VII, which achieved significantly enhanced processing capacity and reliability while maintaining compatibility with MONITOR V, was developed as the OS for the super-large general-purpose computer FACOM 230-75. MONITOR VI, which had almost the same functions as MONITOR VII, was provided for FACOM 230-60.
 The following describes the background to the development of MONITOR V.

1.Background to the development of MONITOR V

 MONITOR IV for FACOM 230-50 which concurrently processed real-time jobs and batch jobs, had been the OS for Fujitsu’s large general-purpose computers. The mechanism of online real-time processing by MONITOR IV was characterized by the resident application programs stored in the memory in advance. So, the data provided from terminal units were able to be processed immediately. The application programs were for telegraph exchanges, data collection/distribution, seat reservation and banking.
 When the company released the plan of MONITOR V, there was growing demand for a TSS capable of performing remote batch processing and demand processing. Demand processing was also called interactive processing because the operator determined a process while interacting with the computer, and new control mechanism was required to realize it.
 To achieve this goal, Fujitsu developed MONITOR V, which controlled batch processing and TSS processing under an integrated concept. It completed a batch function in December 1968 and a TSS function in December 1970. MONITOR V was Fujitsu’s first OS to realize full-scale multi-task control, and led the world in symmetrical multiprocessor using 2 CPUs tightly coupled.

Figure: Schematic of the MONITOR V system

Figure: Schematic of the MONITOR V system

Subsequently Fujitsu developed MONITOR VI for FACOM 230-60. MONITOR VI had almost the same functions as MONITOR VII, which was the OS for the super-large general-purpose computer FACOM 230-75.
2.Features of MONITOR V

 MONITOR V had the following features:

(1) Fujitsu’s first OS to support a TSS (remote batch processing and demand processing) function
 MONITOR V was Fujitsu’s first OS to provide a TSS processing function. It allowed simultaneous and concurrent execution of TSS processing and batch processing, and this dramatically improved the convenience of the computer.
(2) Provision of COP (online COmmon Package) for online processing such as a banking system
 MONITOR V provided MONITOR V COP, a software package that supported the functions commonly used in online systems.
(3) World’s first control of symmetrical tightly coupled multiprocessor
 FACOM 230-60 was the world’s first computer to adopt a symmetrical tightly coupled multiprocessor system that shared the main memory. MONITOR V enabled a 2-CPU system to achieve high processing efficiency, 1.6 to 1.8 times faster than with a 1-CPU system
(4) Fujitsu’s first OS to perform full-scale multi-task control
 Online processing such as TSS processing and banking processing required quick response to a call from a terminal unit, and quick notification of the result of the processing. To meet such requirement, Fujitsu achieved multi-task control in which a program was treated not as a single flow but as several independent flows (called tasks), and each task was given an execution priority according to the degree of its urgency.
(5) Reliability-increasing functions (duplexing of the OS file and patrol diagnosis)
 The OS achieved a function for continuing program loading from an alternative file in the event that a hardware error was detected, by duplexing a magnetic disc that stored the OS file. In addition, the OS was designed to maintain its constant operating state by performing patrol diagnosis every second to ensure that all CPUs were operating normally (to verify that the same result was obtained using different ways of instructions) and that the critical control table had consistency.
3. TSS control function of MONITOR V

 In terms of processing methodology, the TSS of MONITOR V was divided into remote batch processing and demand processing. The following describes the TSS control function of MONITOR V, which performed these types of processing:

(1) Remote batch processing
 Remote batch processing was a mode in which the operator used a terminal to instruct execution of a batch job and extract the output of the execution result using the terminal. All TSS terminals could be used as I/O devices for remote batch processing.
(2) Demand processing
 Demand processing was a processing mode in which the user and the computer were connected online, and mutually exchanged information to execute a job. Demand processing was known also as interactive processing. For such interaction, Fujitsu provided commands for giving instructions to the computer, an interactive language BACCUS (Basic Calculus) for engineering computation, and an interactive language LINED for creating, modifying and editing a file from a terminal.
(3) Terminal control
 As terminals for TSS, communication terminals and I/O devices were available. The communication terminals, at remote locations, connected to the computer via a communication control unit (CCU) The I/O devices were set up around the computer and directly connected to the computer. Fujitsu designed the TSS control program so that the user could operate it without being conscious of the difference in type and connection method of the terminal. To achieve this, transmission control with a communication terminal was performed using CCAS (Communication Control Aid System) of MONITOR V.
(4) Roll-in/roll-out control
 Occasionally, the OS might wait for a response from the user (or another computer) when executing a TSS job of demand processing. The waiting time for receiving a response was much longer than the processing speed of the computer because the user’s thinking speed or the communication line speed was much slower than that of the computer. Additionally, the main memory area occupied by the TSS job remained idle during that time. To avoid such problems, Fujitsu provided the OS with roll-in/roll-out control function. The roll-out was the function in which a program in waiting condition was temporarily transferred from the main memory to a magnetic drum or magnetic disk unit. The roll-in was the function to call back the program to the main memory when it had become executable condition.