FACOM 230-15 SPIRAL and Basic Software for the FACOM 230-10-Computer Museum

SPIRAL was the general name for the basic software programs for the FACOM 230-15 and was announced together with the FACOM 230-15 in April 1970. As the replacement to Fujitsu’s best seller, the FACOM 230-10, the 230-15 was essentially a small general-purpose computer, although it was used in applications that would later become known as the office-computer category. For that reason, SPIRAL had all the functions of a small general-purpose computer operating system together with extra functions, such as kana-enabled COBOL, suited for office-computer applications that aimed to be user friendly. This article provides an overview of FACOM 230-15 SPIRAL as well as the earlier basic software for the FACOM 230-10, which was announced in March 1965.

1. Overview of FACOM 230-15 SPIRAL

SPIRAL, at its core, consisted of a group of software programs for running monitor functions, a paging function, language processing functions, and a communication function. SPIRAL consolidated these functions in order to address the requirements demanded of a small machine at the time — such as a paging function that could handle larger programs, multi-job functions for more convenient operation, and the ability to handle remote processes easily.

（1）Monitor functions: As a result of pursuing a control program suited to a small general-purpose computer, Fujitsu supplied SPIRAL with two monitor functions: Monitor I for single-job control and Monitor II for multi-job control. Either monitor function was capable of batch processes, inquiry processes, and small online processes. Monitor II, however, possessed two frames — main and sub — and, thereby, could run two processes simultaneously (Figure 1).

Figure 1: Example of using the sub frame

（2）Paging function

The software-implemented paging function made it possible to use the internal magnetic drum unit to extend the core memory (Figure 2). This allowed users to execute programs larger than the core memory’s capacity. The paging function worked as follows.

The program to be paged is temporarily stored on the internal magnetic drum unit.
At this time, the program is broken into units, called pages, which the paging function will manage.
When the program is executed, the paging function loads the page to be run from the magnetic drum memory into core memory, where it is run in sequence.

A dual writing method was used to accelerate reading speed from the magnetic drum unit (Figure 3). Dual writing halved the average drum rotation wait time and cut the read access time by half.

Figure 2: Diagram of SPIRAL’s paging principle

Figure 3: Accelerating reads with magnetic drum dual writing

（3）Language process functions: In terms of programming languages, SPIRAL was supplied with COBOL and FOCUS for business processes and FORTRAN for scientific and engineering calculations. SPIRAL’s COBOL language was compliant with the 1969 version of CODASYL COBOL with additional commands for generating reports (control of form pages, tabulation, etc.). The report generation functions were well received by FACOM 230-15 users. FOCUS was a programming language for creating business calculation programs using six types of control cards (which could also be entered from a paper tape unit). FOCUS’s concept, however, was not so much programming as it was marking symbols on preset forms. SPIRAL also came with SL-15, an assembly language with a compiler-like notational format.
（4）Communication function: SPIRAL had a utility function called Corporate, which simplified the use of communication lines.

【Fujitsu】FACOM 230-15 SPIRAL and Basic Software for the FACOM 230-10