dz(4) [bsd man page]
DZ(4) Kernel Interfaces Manual DZ(4) NAME
dz - DZ-11 communications multiplexer SYNOPSIS
/sys/conf/SYSTEM: NDZ dz_units # DZ11; NDZ is in units of boards (8 each) /etc/dtab: #Name Unit# Addr Vector Br Handler(s) # Comments dz ? 160100 310 5 dzrint dzdma # dz11 terminal mux major device number: raw: 2 minor device encoding: bits 0007 specify line on DZ unit bits 0170 specify DZ unit bit 0200 specifies non-blocking open (``CD always on'') DESCRIPTION
A DZ11 provides 8 communication lines with partial modem control, adequate for UNIX dialup use. Each line attached to the DZ11 communica- tions 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 0200 of the minor device number for DZ lines may be set to say that a line is not properly connected, and that the line should be treated as hard-wired with carrier always present. Thus creating the special character device node "2, 130" via mknod /dev/tty02 c 2 130 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. FILES
/dev/tty[0-9][0-9] /dev/ttyd[0-9a-f] dialups /dev/MAKEDEV script to create special files /dev/MAKEDEV.local script to localize special files SEE ALSO
tty(4), dtab(5), autoconfig(8) 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. It is not serious. 3rd Berkeley Distribution January 28, 1988 DZ(4)
Check Out this Related Man Page
cxa(4) Kernel Interfaces Manual cxa(4) Name cxa - CXA16 communications interface Syntax device dhu0 at uba0 csr 0160440 flags 0xffff vector dhurint dhuxint Description A CXA16 provides 16 data-leads-only communication lines with no modem control. The CXA16 conforms to RS423A. The device behaves and looks just like a DHV11 (with the exception of modem control and number of lines) and is specified in the configuration line the same as a DHV11 device. Each line attached to the CXA16 communications multiplexer behaves as described in and can be set to run at any of 16 speeds; see for the encoding. A flags field of 0xffff must be used to specify that all lines are to operate as hardwired. This is done to prevent the line from being treated as a modem control line. The dhu driver normally interrupts on each input character. The and devices operate under the control of the driver. Diagnostics dhu%d: receive fifo overflow The character input fifo overflowed before it could be serviced. This can happen if a hard error occurs when the CPU is running with ele- vated priority, as the system then prints a message on the console with interrupts disabled. This can cause a few input characters to be lost to users. It is not serious. dhu%d:%d DMA ERROR A DMA transfer error has occurred. The unit number and line number are printed. This means that the channel indicated has failed to transfer DMA data within 10.7 microseconds of the bus request being acknowledged or that there is a memory parity error. This may cause a few output characters to be lost. dhu%d: DIAG. FAILURE This indicates that the internal diagnostics have detected an error. dhu%d: DHU HARDWARE ERROR. TX.DMA.START failed The failed to clear the start bit. Normally, this is cleared to signal that a DMA transfer has completed. Files See Also tty(4), MAKEDEV(8) cxa(4)