ZCOM Tables and Data Structures
Physical Terminal Tables
setting bit 1 of the input message tag byte. If there are no shared control receivers, this field will contain a zero. When a control message arrives, it will be delivered to each application in the linked list (as well an any primary control receiver).
PTLIST - Pointer to next PTT on the same port
Contains a pointer to the physical terminal table of the next terminal on the same Mux interface card and port number as the current terminal. These pointers form a circular list of terminals on the same port. Field PTPZLK forms the same circular list, but contains the ZLU number.
PTTXLX - Pointer to next PTT on the express list linkage
This linkage (containing the physical terminal table address) is used to link together physical terminals on the Mux which have messages queued on the express transmit queue. This field is NULL if the terminal is not on the list. It is initialized to NULL by TTGEN and is maintained by the LDM and DAM.
PTTXQX - Express transmit buffer queue
This queue contains the express transmit requests waiting to be sent. It also contains the terminal configuration (zcntl) requests. When a message has been transferred to the card, the buffers are moved to the unacknowledged transmit buffer queue. Once the buffer has been acknowledged as sent or flushed by the card it is removed from the unacknowledged queue and returned to the sending program (if requested by the program).
The express transmit queue is designed for passing critical control (protocol dependent) data to the terminal. In general, none of the normal queue limit mechanisms apply to requests on this queue. Normal user data should NEVER be placed on this queue. An example of appropriate requests would be an X.25 Reset request or X.25 Expedited data. Requests on this queue are always processed first, regardless of any transmit limits that may have been reached.
PTTXLA - Pointer to next PTT on the high priority list linkage
This linkage (containing the physical terminal table address) is used to link together physical terminals on the Mux which have messages queued on their high priority transmit queue. This field is NULL if the terminal is not on the list. It is initialized to NULL by TTGEN and is maintained by the LDM and DAM.
PTTXQA - High priority transmit buffer queue
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