dfa(4) — VAX
Name
dfa − DFA01 communications interface
Syntax
device dz0 at uba0 csr 0160100 flags 0x0 vector dzrint dzxint
Description
The DFA01 contains two DF224-compatible modems with a DZQ11-compatible interface. Each line attached to the DFA01 behaves as described in tty(.). See tty() for the encoding. Lines may operate at 300, 1200, or 2400 baud.
Caution
The DZQ11 interface is capable of baud rates up to 9600 baud, but, because the modem is restricted to speeds of 300, 1200, and 2400 baud, all other baud rates are considered illegal and pass meaningless data.
A flags field of 0x0 must be specified to indicate that the lines are to be treated as modems.
An acucap() entry of dfa01 should be used to describe the 2400 baud autodial attributes used by such programs as tip(,), cu and uucp(.). For pulse tone dialing at 2400 baud, an acucap() entry of dfa01-p should be used. To dial at 1200 baud, the dfa01-1200 or dfa01-1200p (pulse dial) should be used. To use the DFA01 autodialer, the terminal line must be set to no parity.
Any entry in the remote() file that specifies an ACU type of dfa01 must specify no parity. The following example shows how a correct entry in the remote() file may look:
dial2400|2400 Baud attributes:\
:dv=/dev/ttyd0:br#2400:at=dfa01:du:pa=none:
The dfa 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.
MAKEDEV() will produce four terminal lines for the DZQ11 interface. The second and fourth lines are the actual modem lines. The first and third lines pass status information when the modem is on line.
Diagnostics
dz%d: receive fifo overflow.
The character input fifo overflowed before it could be serviced. This can happen if other devices heavily utilize the bus and CPU, preventing interrupts from the DFA01 from being serviced. This may cause a few input characters to be lost to users. It is not serious.
Files
/dev/tty??
/dev/ttyd? Dialups