Basic telecommunications access method
Encyclopedia
Basic Telecommunications Access Method (BTAM) was a low-level programming interface specified by IBM
for use on the IBM System/360 for sending and receiving data through telecommunication lines. Later, IBM specified higher-level interfaces (QTAM
, VTAM
) and entire architectures (TSO
, SNA).
BTAM requires the application program (or transaction processing system
) to handle almost every detail of the protocol. This is harder than using a higher-layer protocol, but it permits interfacing to non-standard devices in non-standard ways. At the time BTAM was introduced, there was little standardization anyway. Like most of the System/360 programming interfaces, BTAM continued to be supported in later iterations of the system architecture. IBM finally withdrew support for BTAM in 2000.
terminals and dealt with specific responses from those terminals, according to the success or failure of the communication channel.
systems such as MTCS
, CICS
and IMS
and underpinned the rise of online
transaction processing for many large commercial Bank
s and Insurance
companies. It was not unusual for BTAM and later developed access methods (such as VTAM) to co-exist, supporting different devices simultaneously under the same transaction processing system.
IBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
for use on the IBM System/360 for sending and receiving data through telecommunication lines. Later, IBM specified higher-level interfaces (QTAM
QTAM
Queued Telecommunications Access Method is an alternative to the simpler Basic Telecommunications Access Method communications access method, introducing built-in queuing. It was developed by IBM as part of DOS/360 and OS/360 and used mainly to transmit batches of data...
, VTAM
VTAM
Virtual Telecommunications Access Method is IBM's software package that provides communications via telecommunication devices for mainframe environments. It is the implementation of Systems Network Architecture for mainframes...
) and entire architectures (TSO
Time Sharing Option
In computing, Time Sharing Option is an interactive time-sharing environment for IBM mainframe operating systems, including OS/360 MVT, OS/VS2 , MVS, OS/390, and z/OS.- Overview :TSO fulfills a similar purpose to Unix login sessions...
, SNA).
BTAM requires the application program (or transaction processing system
Transaction Processing System
A transaction processing system is a type of information system. TPSs collect, store, modify, and retrieve the transactions of an organization. A transaction is an event that generates or modifies data that is eventually stored in an information system. To be considered a transaction processing...
) to handle almost every detail of the protocol. This is harder than using a higher-layer protocol, but it permits interfacing to non-standard devices in non-standard ways. At the time BTAM was introduced, there was little standardization anyway. Like most of the System/360 programming interfaces, BTAM continued to be supported in later iterations of the system architecture. IBM finally withdrew support for BTAM in 2000.
An access method for terminals
BTAM was an access method for interactively communicating with local or remote terminals - usually connected on Channel 0 (System/360) or Channel(s) 0 and/or 4 (System/370 and later). BTAM dynamically built CCW's for reading, writing and "polling"Polling (computer science)
Polling, or polled operation, in computer science, refers to actively sampling the status of an external device by a client program as a synchronous activity. Polling is most often used in terms of input/output , and is also referred to as polled or software driven .Polling is sometimes used...
terminals and dealt with specific responses from those terminals, according to the success or failure of the communication channel.
Key role in Transaction processing systems
BTAM was a key component in IBM's early transaction processingTransaction 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 cannot remain in an intermediate state...
systems such as MTCS
MTCS
MTCS was a transaction processor that ran on IBM mainframe systems under OS/VS1.MTCS was available from IBM and designed for rapid, low to medium volume online processing...
, CICS
CICS
Customer Information Control System is a transaction server that runs primarily on IBM mainframe systems under z/OS and z/VSE.CICS is a transaction manager designed for rapid, high-volume online processing. This processing is mostly interactive , but background transactions are possible...
and IMS
Information Management System
IBM Information Management System is a joint hierarchical database and information management system with extensive transaction processing capabilities.- History :...
and underpinned the rise of online
ONLINE
ONLINE is a magazine for information systems first published in 1977. The publisher Online, Inc. was founded the year before. In May 2002, Information Today, Inc. acquired the assets of Online Inc....
transaction processing for many large commercial Bank
Bank
A bank is a financial institution that serves as a financial intermediary. The term "bank" may refer to one of several related types of entities:...
s and Insurance
Insurance
In law and economics, insurance is a form of risk management primarily used to hedge against the risk of a contingent, uncertain loss. Insurance is defined as the equitable transfer of the risk of a loss, from one entity to another, in exchange for payment. An insurer is a company selling the...
companies. It was not unusual for BTAM and later developed access methods (such as VTAM) to co-exist, supporting different devices simultaneously under the same transaction processing system.
Supported devices
Amongst many other devices supported, BTAM handled:- IBM 1050IBM 1050IBM 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 widely during the 1960s.-General:IBM 1050 Data...
terminals - IBM 2740 terminals
- IBM 2741IBM 2741The IBM 2741 was a printing computer terminal introduced in 1965.It combined a ruggedized Selectric typewriter mechanism with IBM SLT electronics and an RS-232-C serial interface. It operated at about 14.1 characters per second with a data rate of 134.5 bits/second...
terminals - Teletype terminals
- IBM 2260IBM 2260The text-only 960-character monochrome IBM 2260 cathode ray tube video display terminal plus computer keyboard was a 1964 predecessor to the more-powerful color text-and-graphics IBM 3270. The 2260 screen image was normally configured with 12 lines of 80 characters each, which corresponded to IBM...
visual display unit terminals - IBM 3270IBM 3270The IBM 3270 is a class of block oriented terminals made by IBM since 1972 normally used to communicate with IBM mainframes. As such, it was the successor to the IBM 2260 display terminal. Due to the text colour on the original models, these terminals are informally known as green screen terminals...
visual display unit terminals - IBM 2780 terminals used for remote job entryRemote Job EntryRemote job entry is the term used to describe the process of sending jobs to Mainframe computers from remote workstations, and by extension the process of receiving output from mainframe jobs at a remote workstation....