> If this is the case, I do not understand why.  The 16550 (>= "A" assumed)
> has _hardware_ flow control!  If the chip's input buffer should fill
> while the CPU is otherwise occupied, it should simply stop the sender
> with the agreed upon hardware hand-shaking and notify the system via
> interrupt to drain the buffer.

As far as I remember, nothing about this was ever mentioned in any of
the 16550* documentation i ever saw, and as far as i know, it is
simply not true.

Hardware handshaking controlled by the driver != hardware handshaking
implemented in hardware.

I've heard of some 16x50 boards that _do_ do something special to do
real hardware handshaking in hardware (by adding extra gates, etc.)
but to the best of my knowledge, no 16550 of any revision has this
built into hardware.


Do you have a reference that explicitly says something different?


cgd