NAME

dz − DZ-11 communications multiplexer

SYNOPSIS

DZ0 at address 0x3fe008/17760010 vector 0xc0/0300

DESCRIPTION

A dz-11 provides 8 communication lines with partial modem control, adequate for UNIX dialup use.  Each line attached to the DZ-11 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.  In the specification of dz0, indicating “flags 0x04” causes line tty02 to be treated in this way. 

FILES

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

SEE ALSO

tty(4)

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.  If the Berknet is running on a dz line at high speed (e.g. 9600 baud), there is only 1/15th of a second of buffering capacity in the silo, and overrun is possible.  This may cause a few input characters to be lost to users and a network packet is likely to be corrupted, but the network will recover.  It is not serious. 

4th Berkeley Distribution  —  1 August 1985