🚀 go-pugleaf

In article <57j0bj$8go@godzilla.zeta.org.au>,
Craig Dewick <craig@zeta.org.au> wrote:
>In <57ikal$dj4@psilocin.gnu.ai.mit.edu> mikc@gnu.ai.mit.edu (Mike Coughlin) writes:
>
>>    From me --  Here is a research project that needs to be carried 
>>out. How many Sun computers will the 4.7K resistor work on? The idea is
>>that when the terminal is shut off, the resistor will keep the voltage
>>on pin 3 from going away. The terminal will turn the voltage on and off 
>>like it is supposed to when it is working since the resistor has too
>>high a value to stop it. Without the resistor, turning off the terminal
>>will cause the voltage on pin 3 to go to zero for a long time, which is 
>>what a break signal is.
>
>Just do what I do, and put a null modem adaptor on the serial port, and
>use a straight-through cable to connect from that to the terminal
>(assuming your terminals are wired DTE, not DCE). That way the handshake
>lines all loop back, and it seems to get around the effects of phantom
>BREAK's. 

This is interesting. If the Sun port would have a pullup to +12 volts
it should be impossible to boot a sun without a console terminal?

So why does the 4.7k resistor fix the problem ? is the port just oversensitive
to the upgoing edge when the pin goes from -12V to floating.

And if the loopback handshakes also fix the problem it makes things even
more difficult.. they should not have anything to do with break detect
sensitivity.

VesA