Copyright (c) 1983 Regents of the University of California.
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@(#)dmf.4 6.1 (Berkeley) 05/15/85

C 5 dmf - DMF-32, terminal multiplexor "device dmf0 at uba? csr 0170000"

"vector dmfsrint dmfsxint dmfdaint dmfdbint dmfrint dmfxint dmflint"

The dmf device provides 8 lines of asynchronous serial line support. The first two of these have full modem control (the DMF-32 provides other services, but these are not supported by the driver).

Each line attached to a DMF-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 dmf 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 0x0004'' in the specification of dmf 0 would cause line ttyh2 to be treated in this way.

The dmf driver normally uses input silos and polls for input at each clock tick (10 milliseconds).

/dev/tty[hi][0-9a-f]

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

tty(4) "dmf%d: NXM line %d" . No response from 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 rk07's) are present. It is not serious.

"dmf%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. If the Berknet is running on a dh 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.

dmfsrint .

dmfsxint .

dmfdaint .

dmfdbint .

dmflint .

One of the unsupported parts of the dmf interrupted; something is amiss, check your interrupt vectors for a conflict with another device.