No Subject

[jfox@xxxxxxxxxx (Jeff Fox)]

Dear Misc Readers,

>> VIDEO+SERIAL will vector system output to both video and serial.  This
>> will require that bit 0 of output is tied to the rs232 input on the
>> other device.  Also ground the rs232 connection.
>> So you need three wires to a db25 or db9 to a serial port.
>
>Does this mean, that no 12V-5V converters are required? Can I just 
>connect IN0 to TD, OUT0 to RD, and Gnd to SG? 
>
>--
>Penio Penev <Penev@venezia.Rockefeller.edu> 1-212-327-7423

Yes. I have done it directly on several computers.  I tried it
with and without current limiting resistors it doesn't seem to matter.
I figured the -12V might blow the i/o chips on the kit but I have
seen no problems.  I figured the P21 would be ok because I have 
connected the power up backwards before and put 6V in the wrong way,
and I have run it up to 8V (in the right direction) momentarily 
without destroying it.   The +/-12V is going to the i/o latch chips
on the kit anyway not P21.  You can always use some current limiting
resistors, or get a MAXIM xx232 chip to convert from 5V to +/-12 if
you have a system that will not accept 0V and 5V (ok closer to 6)
on an rs232 interface.  I am sure you cannot use very long cables
with some systems, and I would expect some others to really demand
+/- 12V.  But it appears PCs (8088-486) machines that I use have
no problem with 0-6V on a serial line.

Jeff Fox