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a brief hisory of COMAL and Regnecentralen


COMAL (Common Algorithmic Language) is a programming language designed by Benedict Løfstedt and Børge R. Christensen in 1973. The COMAL language was designed for educational purposes and was based on BASIC, but extended this with constructions for structured programming.

Børge Christensen was a math teacher at Tønder Seminarium, a teacher's college. In 1972, the college got a Data Generel Nova 1200 mini computer, but the only programming language for the computer was a BASIC interpreter. Børge Christensen found BASIC to be inadequate for teaching because of the lack of structure in the programs.

Børge Christensen met Benedict Løfstedt at the Computer Science Department at University of Aarhus (DAIMI) og started discussing how to improve BASIC. Inspired by Pascal, Børge Christensen and Benedict Løfstedt, stated to add loop constructions and subroutines to the language to get rid of the notorious GOTO statements in BASIC (see Edsger Dijkstra's letter "Go To Statement Considered Harmful" in CACM, March 1968). The new programming language was called COMAL.




The first version, COMAL 75, was implemented on a Data Generel Nova 1200 mini computer under the operating system SOS by Per Christiansen and Knud Christensen at Tønder Statsseminarium, using X.BASIC fra Data General as the starting point. In October 1975, it was ported to DG RDOS by A/S REGNECENTRALEN in Copenhagen, and in July 1976, the port to RC3600 MUS operating system began. RC COMAL for the RC700 was released in May 1977.




ID-COMAL was a version of COMAL developed at Instituttet for Datateknik (ID), Danmarks Tekniske Højskole (DTH) under supervision of Tom Østerby in the late 70s.

RC700 COMAL was made by Regnecentralen based on ID-COMAL. In 1980, Knud Henningsen and Erik Jeppesen from Regnecentralen adapted ID-COMAL for the RC700 micro computer and changed it to be more compatible with the RC BASIC/COMAL for the RC7000 mini computer (RCSL 42-i1578). RC700 COMAL was a standalone system running on top of a proprietary system monitor.


RC700 comal rev. 01.11
Download: RCCOMAL111.IMD

RC700 comal rev. 01.12

RC700 comal rev. 01.12.
Download: RCCOMAL112.IMD
Documentation: RC700 COMAL Brugermanual

RC700 comal rev. 01.13

RC700 comal rev. 01.13.
Download: RCCOMAL113.IMD
Documentation: Supplement til RC700 COMAL Brugermanual


RC700 COMAL-80


At the end of the 1970s, a number of different incompatible versions of COMAL had emerged, so a COMAL standard was needed to ensure consistency between the different implementations. In 1980, a working group published a report »COMAL 80 PROGRAMMING LANGUAGE, proposal« with a proposal for the the nucleus of the COMAL 80 language. The members of the working group (March 1980) included:

RC700 COMAL-80 was an implementation compatible with the COMAL-80 language specification. RC COMAL-80 vers. 1.06 with a screen-oriented editor was released in November 1982, and the CP/M version was released in June 1983.


RC700 COMAL80 1.8 Distribution Disk

RC700 COMAL80 Distribution Disk, release 1.8, (c) RC COMPUTER. This disk can be used for making new COMAL80 system and data disks.
Download: COMAL18.IMD

RcComal80 rev 1.0

RcComal80 rev 1.0 (CP/M version).
Download: RCCOMAL80-100.IMD

RC700 comal80 rev. 1.06

RC700 comal80 rev. 1.06 standalone system.
Download: RCCOMAL80-106.IMD

RC700 comal80 rev. 1.07

RC700 comal80 rev. 1.07 standalone system.
Download: RCCOMAL80-107.IMD

RC700 comal80 rev. 1.08

RC700 comal80 rev. 1.08 standalone system.
Download: RCCOMAL80-108.IMD
Documentation: COMAL80 Brugervejledning

For more information about the history of COMAL, see the COMAL section at DDHF.