Reference Guide

ZCOM Tables and Data Structures
Physical Terminal Tables
Chapter 3 73
This queue contains the high priority transmit requests waiting to be
sent. It also contains the terminal configuration (zcntl) requests. The
data on this queue is processed only after all express transmit data has
been processed. 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). Note that requests on this queue
are subject to the unacknowledged and port transmit limits.
PTTXLB - Pointer to next PTT on low priority list linkage
As for PTTXLA above, except that the linkage pertains to the low
priority transmit queue.
PTTXQB - Low priority transmit buffer queue
The low priority queue is operated in a similar manner to the high
priority queue. Data on this queue is processed only after all express and
high priority data has been processed. Note that requests on this queue
are subject to the unacknowledged and port transmit limits.
PTTXQC - Unacknowledged transmit buffer queue
This queue contains the buffers from PTTXQA/B after they have been
transferred to the interface card, and until they have been acknowledged
as sent (or aborted) by the Mux interface card.
PENDG_TXREQ - Next request of $DATA in unack’d transmit queue
This field is used internally by the ZCOM subsystem.
PTPZLK - ZLU of next PTT on this port
Contains the ZLU number of the next terminal which is on the same
Mux interface and port as this terminal. These ZLU numbers form a
circular list of terminals on the same port. Field PTLIST forms the same
circular list, but contains the physical terminal table memory address.
PTDRST - Terminal status
The terminal status is maintained by the driver in this field. The status
change requests from application programs are updated in this field
after they are successfully passed to the interface card. The driver uses
this value to reset the terminal status on the Mux interface after a
powerfail or reset.