gtps4m1e | System Generation |
The communications lines that are supported by the TPF system may be divided into 3 categories: SNA, non-SNA, and communications console support.
Users can implement TPF's Advanced Communications Function (ACF), which is required for TPF's implementation of SNA and extends the basic support provided for SDLC as well as providing support for ALC terminals connected through ALCI. Considerations for this support are described in TPF ACF/SNA Network Generation and TPF ACF/SNA Data Communications Reference.
These 3 protocols are known as non-SNA communications support. SLC is associated with lines that are connected to a transmission control unit (TCU) such as the 3705. The 3705 itself is run under the control of the 3705 Emulator Program (3705/EP) and can be attached to the host processor executing TPF only on byte multiplexor channel 0. BSC runs on a 3745 loaded with the partitioned emulator program (PEP). 3270 local control units may execute TPF on either a byte multiplexor channel or a block multiplexor, attached to logical channel 0.
Users of the High Performance Option (HPO) feature also have communications considerations that must be addressed. They are introduced later in High Performance Option Feature.
This publication does not address the generation of 3705/EP, 3745/PEP, or ACF/NCP. The reader is directed to the appropriate publications for those programs for this aspect of system generation. Where necessary, reference will be made to certain aspects of this separate generation as it relates to the TPF generation.
Another general consideration that the system designer of the TPF communication support must be aware of is the relationship of the communications support, specifically each of the protocols supported, to the applications that will be written/employed on the TPF system. The TPF message router (see Message Router Support) allows you to define an application as either an old or new application. The connotation here is that non-SNA communications-supported protocols interface with old applications, where the terminal address (for example, the line number, terminal interchange number) is used as an index number (an ordinal number) for a fixed file record (typically an agent assembly area (AAA)); whereas a new application does not employ this concept. A bridge technique is used for 3270/SDLC terminals to communicate with an old application via a pseudo terminal address.
Although TPF can support a system configuration having all of the previous types of lines, it is probable that only a limited number of these types would be used in a particular system. Each type of line can be used only with prescribed types and models of equipment such as terminals, concentrators, transmission control units, processors, and so on.
After your system designer has arrived at a final configuration showing the various types of lines, the number of lines in each type, and equipment such as transmission control units, controllers, concentrators, terminals, and so on that are attached to each line, you are ready to code certain sets of macros that allow for the generation and loading of the communication database.