
param <iface> [<param> [<value>]]
     Param invokes a device-specific control routine.  A simple 'param
<iface>' will give a list of available parameters and their current
values, for the interface <iface>.  <param>  can be the literal name
of the parameter, or it can be its numeric index (see below).  <value>
is either a boolean value (such as ON or OFF) converted to 1 or 0, or
an integer.

     On a serial interface,  the param command sends control packets
over the serial port.  For example, 'param port1 txdelay  255' will set
the keyup timer (called txdelay) on the KISS TNC configured as port1 to
2.55 seconds (255 x .01 sec).  In most TNC KISS implementations, a 10ms
tick count is used, so that (for example) 30 means 300ms, and a limit
of 255 is imposed on <value>.

     The SCC driver, on the other hand, allows a limit of 65535 for <value>.

Currently supported <params> include:
Name (index)      Definition     

TxDelay (1)       keyup delay before sending data
Persist (2)       the csma persistence (range 0-255) (probability of success
SlotTime (3)      the channel access slottime (how often we throw the dice)
TxTail (4)        time to keep transmitter keyed up after end of packet
FullDup (5)       simultaneous TX and RX enabled when ON
Hardware (6)
TxMute (7)
DTR (8)           Assert DTR when true, de-assert when false.
RTS (9)           Assert RTS when true, de-assert when false.
Speed (10)        async baud, etc.
EndDelay (11)
Group (12)        SCC iface group id and TX-interlock style
Idle (13)
Min (14)
MaxKey (15)       maximum time to allow transmitter to be keyed (0 - 65000)
Wait (16)
Down (129)        De-assert RTS and DTR on serial port
Up (130)          Assert RTS and DTR on serial port
Blind (131)       Ignore CTS and DSR transitions on serial port
RcvMode (253)     set packet driver receive mode
Return2 (254)     TNC partially (!!) exits KISS mode
Return (255)      TNC exits KISS mode

Additional information for selected <params>:

The GROUP param specified an integer whose low-order 8 bits provide a
transmit-group number (0 implies no group membership), and whose remaining
bits provide flags describing that group's behaviour:
1 => only transmit when all receive channels in this group are clear.
2 => don't transmit simultaneously on interfaces in this group.

