dz(4)
NAME
dz − DZ11/DZ32 communications multiplexer
SYNTAX
device dz0 at uba0 csr 0160100 flags 0x????
vector dzrint dzxint
DESCRIPTION
A DZ11/DZ32 provides 8 communication lines with partial modem control, adequate for dialup use. Each line attached to the DZ11/DZ32 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 2 to be treated in this way.
The dz driver normally uses its input silos and polls for input at each clock tick (10 milliseconds) rather than taking an interrupt on each input character.
DIAGNOSTICS
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.
FILES
/dev/tty??
/dev/ttyd?(modem lines only)