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@(#)dmz.4 6.1 (Berkeley) 04/08/86

C 5 dmz - DMZ-32 terminal multiplexor "device dmz0 at uba? csr 0160540"

"vector dmzrinta dmzxinta dmzrintb dmzxintb dmzrintc dmzxintc"

The dmz device provides 24 lines of asynchronous serial line support. The DMZ-32 is connected to an H3014 distribution panel by a cable that may be up to a mile in length and the two ends communicate using a T1 protocol. Modem control on all ports is available as an option for the H3014 distribution panel.

Each line attached to a DMZ-32 serial line port behaves as described in tty (4). Input and output for each line may independently be set to run at any of 16 speeds; see tty (4) for the encoding.

Bit i of flags may be specified for a dmz to to say that a line is not properly connected, and that the line should be treated as hard-wired with carrier always present. Thus specifying ``flags 0x000004'' in the specification of dmz 0 would cause line ttya2 to be treated in this way.

The dmz driver normally uses input silos and polls for input at each clock tick (10 milliseconds). It uses an adaptive algorithm on output to decide whether to use programmed I/O or DMA based on the amount of data to send.

/dev/tty[abc][0-9a-n] tty(4) "dmz%d: NXM line %d" . No response from the UNIBUS on a DMA transfer within a timeout period. This is often followed by a UNIBUS adapter error. This occurs most frequently when the UNIBUS is heavily loaded and when devices which hog the bus (such as RK07s) are present. It is not serious.

"dmz%d: silo overflow" . The character input silo overflowed before it could be serviced. This can happen if a hard error occurs when the CPU is running with elevated priority, as the system will then print a message on the console with interrupts disabled. It is not serious.