TTY_SILOTIME defines the interval at which the DMF32 hardware
    polls the input silo for received characters. The DMF32
    asynchronous terminal controller can delay the generation
    of a single input interrupt until multiple characters have
    accumulated in the input silo. TTY_SILOTIME specifies the number
    of milliseconds that the characters are allowed to accumulate
    prior to the generation of an input interrupt by the hardware.

                                   NOTE

       The remainder of this discussion is of interest to customers
       who use Digi Edgeport hardware.

    TTY_SILOTIME controls latency, trading throughput and system
    overhead for latency. The default value for TTY_SILOTIME is 8.
    This value is multiplied by 100 and is used as a count of the
    number of times to send a query to the device for more data after
    a character transmit or receive is performed.

    If no input (or no subsequent output) is seen after 800 responses
    to the query, the driver stops sending queries to the device and
    waits for an input interrupt. Reducing the TTY_SILOTIME value
    allows the device to buffer more data, with slightly higher
    latency.

    Increasing the value of TTY_SILOTIME makes the device more
    sensitive to latency but decreases buffering and overall
    throughput; it also adds more system and USB overhead. Setting
    TTY_SILOTIME to zero causes the driver to send input queries to
    the device continually. This setting causes the lowest latency,
    the highest system overhead, and the lowest throughput possible.