[c-nsp] Cisco 7200 AUX port pseudo-break problem

[Miquel van Smoorenburg]

On Thu, 2005-08-25 at 09:29 -0400, Ed Ravin wrote:
> On Wed, Aug 24, 2005 at 11:13:36PM -0700, Ted Mittelstaedt wrote:
> > 
> >   The problem is that a Break signal isn't actually a real character.
> > The
> > following explains it more throughly with some suggested fixes:
> > 
> > http://www.cisco.com/warp/public/770/fn-tsbreak.html
> 
> I like this suggestion:
> 
>   * The "Soldering Iron" solution 
>   If you tie a 4.7K resistor (1/4 Watt) between pins 3 and 25 of the ttya
>   port, you electrically prevent a BREAK signal either from the key or from
>   disconnecting or powering down the terminal. This prevents intentional
>   halts except by removing the resistor, but does allow recabling.
> 
> This is almost what I want.  I would rather it was remotely switchable,
> so I can still send a BREAK when I need to fix problems on the NetBSD
> box.  Perhaps a circuit that recognizes two BREAK signals in a row,
> like the Hayes modem +++ escape?

Why a circuit ? Patch the BSD kernel so that it only enters the monitor
if you send 2 breaks, or a break and space, or whatever. Remember, you
have the source.

Mike.