DUCS (Display Unit Control System) was a teleprocessing monitor from CFS Inc. It was one of two early local teleprocessing packages for IBM's

DOS/VSE VSEn (''Virtual Storage Extended'') is an operating system for IBM mainframe computers, the latest one in the DOS/360 lineage, which originated in 1965. DOS/VSE was introduced in 1979 as a successor to DOS/VS; in turn, DOS/VSE was succeeded by ...

environment. DUCS provided an

interface Interface or interfacing may refer to: Academic journals * ''Interface'' (journal), by the Electrochemical Society * '' Interface, Journal of Applied Linguistics'', now merged with ''ITL International Journal of Applied Linguistics'' * '' Int ...

and

access method An access method is a function of a mainframe operating system that enables access to data on disk, tape or other external devices. Access methods were present in several mainframe operating systems since the late 1950s, under a variety of name ...

for programmers to 'talk' to monitors. Such access methods later became known as

API An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how ...

s. Initially written for the

IBM 2260 The text-only monochrome IBM 2260 cathode-ray tube (CRT) video display terminal (Display Station) plus keyboard was a 1964 predecessor to the more-powerful IBM 3270 terminal line which eventually was extended to support color text and graphic ...

running under DOS on IBM

mainframe A mainframe computer, informally called a mainframe or big iron, is a computer used primarily by large organizations for critical applications like bulk data processing for tasks such as censuses, industry and consumer statistics, enterpris ...

s, the original product was free for IBM users. With the advent of

DOS/VS Disk Operating System/360, also DOS/360, or simply DOS, is the discontinued first member of a sequence of operating systems for IBM System/360, System/370 and later mainframes. It was announced by IBM on the last day of 1964, and it was first de ...

and the

IBM 3270 The IBM 3270 is a family of block oriented display and printer computer terminals introduced by IBM in 1971 and normally used to communicate with IBM mainframes. The 3270 was the successor to the IBM 2260 display terminal. Due to the text ...

series terminals, the original author commercialized the product, circa 1970. The company added transparent remote access about 1972. The product is believed to be the first non-IBM publicly available commercial

software package Software package may refer to: * Package (package management system), in which individual files or resources are packed together as a software collection that provides certain functionality as part of a larger system * Software suite, which provid ...

to transmit data via

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioiso ...

.CFS brochure, 1976

Application

DUCS differed from competing products such as

Westi Westi (Westinghouse Teleprocessing Interface System) was one of two early local teleprocessing packages for IBM's DOS/VSE environment. Westi stood for Westinghouse Terminal Interactive. Westi provided an interface and access method for programme ...

and IBM's own

CICS IBM CICS (Customer Information Control System) is a family of mixed-language application servers that provide online transaction management and connectivity for applications on IBM mainframe systems under z/OS and z/VSE. CICS family products ...

in that it was subordinate to the

application Application may refer to: Mathematics and computing * Application software, computer software designed to help the user to perform specific tasks ** Application layer, an abstraction layer that specifies protocols and interface methods used in a c ...

's mainline program. Westi, for example, ''was'' the mainline program and users wrote

subroutine In computer programming, a function or subroutine is a sequence of program instructions that performs a specific task, packaged as a unit. This unit can then be used in programs wherever that particular task should be performed. Functions ma ...

s to read and write data to and from terminals and discs. This real time paradigm became known as

transaction processing Transaction processing is information processing in computer science that is divided into individual, indivisible operations called ''transactions''. Each transaction must succeed or fail as a complete unit; it can never be only partially compl ...

. DUCS reversed that model in that it was, in fact, a subroutine package that read from and wrote to monitors, both local and remote. While DUCS was considerably easier to program and use, it also placed the onus of task management upon the programmer. Correctly designed, a DUCS program was faster than any competing package or access method.

Development

2260

Dick Goran wrote the original DOS 2260 package. Its popularity made him realize it had potential as a commercial product, and he left IBM about 1970, and incorporated in

Brookline, Massachusetts Brookline is a town in Norfolk County, Massachusetts, in the United States, and part of the Boston metropolitan area. Brookline borders six of Boston's neighborhoods: Brighton, Allston, Fenway–Kenmore, Mission Hill, Jamaica Plain, and ...

as CFS, Inc.

3270

In 1972, IBM released

with the

IBM/370 The IBM System/370 (S/370) is a model range of IBM mainframe computers announced on June 30, 1970, as the successors to the System/360 family. The series mostly maintains backward compatibility with the S/360, allowing an easy migration path f ...

and the first

terminals, and CFS began a rewrite for the new products. Former

New York City New York, often called New York City or NYC, is the most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the most densely populated major city in the U ...

IBMer, Leigh Lundin, wrote DUCS Remote, a bi-sync module to handle remote teleprocessing. The bi-sync handler was only 4k, in contrast to IBM's BTAM at 28k,

QTAM Queued Telecommunications Access Method (QTAM) is an IBM System/360 communications access method incorporating built-in queuing. QTAM was an alternative to the lower level Basic Telecommunications Access Method (BTAM). History QTAM was announ ...

at 36k, and TCAM at 42k, and

VTAM Virtual Telecommunications Access Method (VTAM) is the IBM subsystem that implements Systems Network Architecture (SNA) for mainframe environments. VTAM provides an application programming interface (API) for communication applications, and c ...

which started at 48k.

Demos

Lundin wrote games in Fortran and

Assembler Assembler may refer to: Arts and media * Nobukazu Takemura, avant-garde electronic musician, stage name Assembler * Assemblers, a fictional race in the ''Star Wars'' universe * Assemblers, an alternative name of the superhero group Champions of A ...

and Goran in

COBOL COBOL (; an acronym for "common business-oriented language") is a compiled English-like computer programming language designed for business use. It is an imperative, procedural and, since 2002, object-oriented language. COBOL is primarily ...

to demonstrate the API for programmers. To model IBM's new

light pen A light pen is a computer input device in the form of a light-sensitive wand used in conjunction with a computer's cathode-ray tube (CRT) display. It allows the user to point to displayed objects or draw on the screen in a similar way to a to ...

, programmers contributed a simple

tic-tac-toe Tic-tac-toe (American English), noughts and crosses (Commonwealth English), or Xs and Os (Canadian or Irish English) is a paper-and-pencil game for two players who take turns marking the spaces in a three-by-three grid with ''X'' or ''O''. ...

(

noughts and crosses Tic-tac-toe (American English), noughts and crosses (Commonwealth English), or Xs and Os (Canadian or Irish English) is a paper-and-pencil game for two players who take turns marking the spaces in a three-by-three grid with ''X'' or ''O''. T ...

), possibly the only practical use of the subsequently discontinued light pen.

Marketing

DUCS was sold in North America by CFS, Inc, Brookline, Ma. For overseas sales, CFS engaged in both mail order and local vendors.

References

{{DEFAULTSORT:Ducs (Software) Transaction processing IBM mainframe software