Dropped character question

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Hi,

On Wed, Aug 04, 1999 at 07:57:43AM +0200, Marc SCHAEFER wrote:
> > I set Transmit Data flow control to Hardware flow control (CTS) and recieve
> > data software flow control to off.
> 
> flow control should always be RTS/CTS. If you don't have receive flow
> control (ie RTS), then you risks input overruns much more, even with
> a 16550A.

I tend to disagree on this - as the RTS flow control has to be done by the
kernel drivers, it will only be activated if the kernel RX buffers fill
(and not if the 16550A's buffers are full).  If the kernel buffers fill,
it means your (our) application hasn't been fast enough to read an 38400
bps data stream - meager 4 Kbyte/sec. - from the tty device, and this
hints at *REAL* problems in the system or the application.

So, while I agree that CTS flow control is a very good idea, RTS isn't
that important.

OTOH, on Linux (and most other Unix systems I know thoroughly) you can't 
activate CTS without RTS anyway - it's both or nothing :)

[Notable exception is SCO with the native serial driver, but that's broken
anyway and people should use FAS instead]

gert
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Gert Doering - Munich, Germany                             gert@greenie.muc.de
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