5. Basic telecommunications access
method
• A low-level programming interface specified
by IBM for use on the IBM System/360
• For start-stop and binary
synchronous telecommunications terminals.
7. Basic telecommunications access
method
• BTAM requires the application program
or transaction processing system to handle
almost every detail of the protocol.
• Transaction processing is a style of computing
that divides work into individual, indivisible
operations, called transactions
8. Basic telecommunications access
method
• This is harder than using a higher-layer
protocol, but it permits interfacing to non-
standard devices in non-standard ways
9. Basic telecommunications access
method
• BTAM was an access method for interactively
communicating with remote terminals
• BTAM dynamically built CCW's for reading,
writing and "polling" terminals
• Dealt with specific responses from those
terminals, according to the success or failure
of the communication channel.
10. Basic telecommunications access
method
• A channel command word (CCW) is
an instruction to a specialized I/O channel
processor which is, in fact, a finite state
machine
• Polling refers to actively sampling the status of
an external device by a client program as a
synchronous activity
11. Basic telecommunications access
method
• 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.
14. Queued Telecommunications Access Method
• Queued Telecommunications Access
Method (QTAM) is an IBM
System/360 communications access
method incorporating built-in queuing.
16. Queued Telecommunications Access Method
• Queuing is referring to message queues
• These are software-
engineering components used for interprocess
communication (a set of methods for the
exchange of data among multiple threads)
17. Queued Telecommunications Access Method
• Threads being the smallest sequence of
programmed instructions that can be
managed independently
18. Queued Telecommunications Access Method
• QTAM consisted of a Message Control
Program (MCP) and zero or more Message
Processing Programs (MPP)
• The MCP handled communications with the
terminals, identified input messages and
started MPPs to process them as required
20. Queued Telecommunications Access Method
• These macros defined:
• The lines and terminals comprising the
system,
• The datasets required,
• And the procedures used to process received
and transmitted messages.
21. Queued Telecommunications Access Method
• The MPPs, incorporating logic to process the
various messages, were supplied by the
installation, and used standard OS/360 data
management macros.
23. Telecommunications Access Method
• Telecommunications Access Method (TCAM) is
an access method that provides access to
terminals units within a teleprocessing
network.
24. Telecommunications Access Method
• Teleprocessing is a term coined by IBM and is
used to describe a computer with the
capability of connecting to another computer
or network device.
25. Telecommunications Access Method
• Though TCAM provided similar functionality
to QTAM, which it replaced, It had its
advantages over QTAM
26. Telecommunications Access Method
• It was said to have:
– Improved buffering, with more buffering options.
– Improved organization of message queuing on
disk including multiple volume support.
– Back-up copies of messages maintained on disk.
27. Telecommunications Access Method
• It was said to have:
– Improved testing and debugging (including off-line
testing, improved debugging, online terminal
testing, and logging.)
– Improved line handling for inquiry applications.
28. Telecommunications Access Method
• It was said to have:
– "Significantly increases speed and efficiency over
QTAM."
– Improved operator monitoring and control.
– Binary Synchronous Support.
– Checkpointing.
29. Telecommunications Access Method
• Binary Synchronous Communication, aka
BSC or Bisync,
• Is an IBM character-oriented, half-duplex link
protocol, announced in 1967
30. Telecommunications Access Method
• Checkpointing is a technique for inserting fault
tolerance into computing systems.
• It basically consists of storing a snapshot of
the current application state
• It may use it later on for restarting the
execution in case of failure.
32. Virtual Telecommunications Access Method
• VTAM provides an application programming
interface (API) for communication
applications,
• IT controls communication equipment such as
adapters and controllers.
34. Virtual Telecommunications Access Method
• After a series of delay, VTAM was introduced
in 1974 as a major component of SNA
(Systems Network Architecture)
35. Virtual Telecommunications Access Method
• VTAM is an access method software that
allows application programs to read and write
data to and from external devices.
• It is called 'virtual' because it was introduced
at the time when IBM was introducing virtual
storage
36. Virtual Telecommunications Access Method
• VTAM is an access method software that
allows application programs to read and write
data to and from external devices.
• It is called 'virtual' because it was introduced
at the time when IBM was introducing virtual
storage
37. Virtual Telecommunications Access Method
• Some Features Of VTAM Is That:
• Supports several network protocol
• Supports 'cross-domain' services