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

IBM International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...

's DOS/VSE 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'' * '' Inter ...

and

access method An access method is a function of a mainframe computer, 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 ...

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

API An application programming interface (API) is a connection between computers or between computer programs. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how to build ...

s. Initially written for the

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

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 del ...

and the

IBM 3270 The IBM 3270 is a family of Block-oriented terminal, 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 ter ...

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 to transmit data via

satellite A satellite or an artificial satellite is an object, typically a spacecraft, placed into orbit around a celestial body. They have a variety of uses, including communication relay, weather forecasting, navigation ( GPS), broadcasting, scient ...

.CFS brochure, 1976

Application

DUCS differed from competing products such as Westi and IBM's own

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

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 ...

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

subroutine In computer programming, a function (also procedure, method, subroutine, routine, or subprogram) is a callable unit of software logic that has a well-defined interface and behavior and can be invoked multiple times. Callable units provide a ...

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

transaction processing In computer science, transaction processing is information processing 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 c ...

. 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 an affluent town in Norfolk County, Massachusetts, United States, and part of the Greater Boston, Boston metropolitan area. An exclave of Norfolk County, Brookline borders six of Boston's neighborhoods: Brighton, Boston, Brighton ...

as CFS, Inc.

3270

In 1972, IBM released

with the

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

and the first

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

New York City New York, often called New York City (NYC), is the most populous city in the United States, located at the southern tip of New York State on one of the world's largest natural harbors. The city comprises five boroughs, each coextensive w ...

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 Basic Telecommunications Access Method (BTAM) is a low-level programming interface specified by IBM for use on the IBM System/360 for start-stop and binary synchronous telecommunications terminals. Later, IBM specified higher-level interfaces QTA ...

at 28k,

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

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 contro ...

which started at 48k.

Demos

Lundin wrote games in Fortran and Assembler 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 (English in the Commonwealth of Nations, Commonwealth English), or Xs and Os (Canadian English, Canadian or Hiberno-English, Irish English) is a paper-and-pencil game for two players who ta ...

(

noughts and crosses Tic-tac-toe (American English), noughts and crosses (English in the Commonwealth of Nations, Commonwealth English), or Xs and Os (Canadian English, Canadian or Hiberno-English, Irish English) is a paper-and-pencil game for two players who ta ...

), 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