gene@uicsl.csl.uiuc.edu (07/26/88)
My solution for sending a "break" (although it is only for the technically
inclined) was as follows: I had built my own RS-232 interface for use with
a stand-alone modem.....User-port pin "M" drives this and is "hi" at quies-
cence and goes "low" for data: I simply intercepted this connection and
inserted two diodes to "OR" either the Commodore, or an added "one-shot
monostable" into the interface circuit. The mono used 2/3 of a CD4007
CMOS which is "hi" quiescently" and with a tap of a "BREAK-button", goes
"low" for approx. 280 ms.....which is probably quite arbitrary, but I copied
it from one of our commercial terminals. (The diodes have their anodes "common"
and go to the RS-232 interface. The cathodes go, one each to the Commodore
pin "M", and the output of the "mono". (All the power for interface and
mono are taken from the Commodore).
For those who are willing to tamper with their custom-type Commodore
modems, I suspect you could easily intercept the "M" pin and insert the same
diodes mentioned above. Commodore pin 2 is the +5 volts source, and pins
N,12,A,1 are all ground. You could probably find room to improvise the
mono- circuit and push-botton within the existing modem case.