ZCOM Tables and Data Structures

Logical Terminal Tables

LTZSHRCVRS - Pointer to a linked list of indirect shared receivers

This field contains a pointer to a linked list of shared receivers that wish to receive data messages from an inbound multiplexed terminal. Each entry in the linked list represents one program. If the ZCOM_LTFLAG_IMX bit in ltflag is set, the system sets up this field on a zset_rcvr (mode 0) call. All incoming messages will be received by the inbound multiplexing program, which will then route the data to each of the receivers specified in this linked list.

LTHLDQ - Sub-packet holding queue

This queue is a holding queue for partial messages to an inbound multiplexed terminal.

LTDHQN - Data holding queues

For use by an application program to store temporary data for each terminal. Only the queue header is stored in these fields, as the data itself is stored in the ZCOM subsystem buffers.

LTUSER - User-maintainable area

The fields in the user-maintainable area may be modified by the zltup call. The area consists of the following fields (up to the end of the terminal table):

LTADDR - Logical terminal address

Holds the logical terminal addressing information needed to recognize the correct logical terminal in a group of multiplexed terminals. This is a 10-byte field, however the multiplexing program may use these bytes according to the specific requirements of the protocol.

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Chapter 3