Queued Telecommunications Access Method (QTAM) is an

IBM System/360 The IBM System/360 (S/360) is a family of mainframe computer systems that was announced by IBM on April 7, 1964, and delivered between 1965 and 1978. It was the first family of computers designed to cover both commercial and scientific applic ...

communications

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 ...

incorporating built-in queuing. QTAM was an alternative to the lower level Basic Telecommunications Access Method (BTAM).

History

QTAM was announced by IBM in 1965 as part of

OS/360 OS/360, officially known as IBM System/360 Operating System, is a discontinued batch processing operating system developed by IBM for their then-new System/360 mainframe computer, announced in 1964; it was influenced by the earlier IBSYS/IBJOB ...

and

DOS/360 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 ...

aimed at inquiry and

data collection Data collection or data gathering is the process of gathering and measuring information on targeted variables in an established system, which then enables one to answer relevant questions and evaluate outcomes. Data collection is a research com ...

. As announced it also supported remote job entry (RJE) applications, called ''job processing'', which was dropped by 1968. Originally QTAM supported the

IBM 1030 The IBM 1030 Data Collection System was a remote terminal system created by IBM in Endicott, New York in 1963, intended to transmit data from remote locations to a central computer system. Description The system consisted of the following compone ...

Data Collection System,

IBM 1050 IBM 1050 Data Communications System is a computer terminal subsystem to send data to and receive data from another 1050 subsystem or IBM computer in the IBM 1400, IBM 7000 or System/360 series. It first became available in 1963 and was used wid ...

Data Communications System, the IBM 1060 Data Communications System, the IBM 2671 Paper Tape Reader, AT&T 83B2 Selective Calling Stations, Western Union Plan 115A Outstations, and AT&T

Teletype Model 33 The Teletype Model 33 is an electromechanical teleprinter designed for light-duty office use. It is less rugged and cost less than earlier Teletype machines. The Teletype Corporation introduced the Model 33 as a commercial product in 1963 aft ...

or 35 Teletypewriters. By 1968 terminal support had expanded to include 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 ...

display complex, and the

IBM 2740 The IBM 2741 is a printing computer terminal that was introduced in 1965. Compared to the teletypewriter machines that were commonly used as printing terminals at the time, the 2741 offers 50% higher speed, much higher quality printing, quieter o ...

communications terminal. QTAM devices were attached to a System/360 multiplexor channel through an IBM 2701 Data Adapter or IBM 2702 Transmission Control. By 1968 support for the IBM 2703 Transmission Control Unit had been added. QTAM was succeeded by TCAM which provided roughly similar facilities, but was not supported under DOS.

Structure

QTAM consists of a Message Control Program (MCP) and zero or more Message Processing Programs (MPP). The MCP handles communications with the terminals, identifies input messages and starts MPPs to process them as required. This is similar in concept to the much later internet service daemon (inetd) in unix and other systems. The MCP is assembled by the user installation from a set of macros supplied by IBM. These macros define the lines and terminals comprising the system, the ''datasets'' required, and the procedures used to process received and transmitted messages. The MPPs, incorporating logic to process the various messages, are supplied by the installation, and use standard OS/360 or DOS/360 data management macros OPEN, CLOSE, GET, and PUT.

PL/I PL/I (Programming Language One, pronounced and sometimes written PL/1) is a procedural, imperative computer programming language developed and published by IBM. It is designed for scientific, engineering, business and system programming. It ...

includes the TRANSIENT file declaration attribute to allow MPPs to be written in a high-level language.

References

Other sources

* * * IBM mainframe operating systems {{compu-network-stub