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@(#)dz.4 6.2 (Berkeley) 05/16/86

C 4 dz - DZ-11 communications multiplexer "device dz0 at uba0 csr 0160100 vector dzrint dzxint" A DZ11 provides 8 communication lines with partial modem control, adequate for UNIX dialup use. Each line attached to the DZ11 communications multiplexer behaves as described in tty (4) and may be set to run at any of 16 speeds; see tty (4) for the encoding.

Bit i of flags may be specified for a dz 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 0x04'' in the specification of dz0 would cause line tty02 to be treated in this way.

The dz driver monitors the rate of input on each board, and switches between the use of character-at-a-time interrupts and input silos. While the silo is enabled during periods of high-speed input, the driver polls for input 30 times per second.

/dev/tty[0-9][0-9]

/dev/ttyd[0-9a-f] dialups

tty(4)

dz%d: silo overflow. The 64 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.