[rescue] Rescued Sun servers, now what?!
mouse at Rodents-Montreal.ORG
Sun Feb 19 17:41:00 CST 2012
>> You might hook up a serial console, [...]
> That's exactly what I'm trying to do,
Heh. And we come full circle.
> and what my original question was about, since I have an Ampex 220
> terminal but I don't have the cable to connect it to the U10.
If you have the connectors and a few tools, it's not all that hard to
build the cable yourself. A voltmeter and a couple of resistors is
usually enough to figure out which data pin is which, and then
soldering wires to connectors is all that's left.
Since both the Sun and the terminal appear to use DB25s, they probably
follow the standard at least as much as most serial devices do - which
isn't as far as we might wish, but it's probably enough for this. I
would start by shorting pins 2 and 3 together on the terminal's main
port - with a small bit of wire if it's a female connector, with a
small screwdriver or some such if male - and see if it then echoes what
you type. If not, it's going to need more advice than I can give here
- it could be temrinal configuration, it could be a need for DSR or
some such, it could be a nonstandard pinout, it could be something
There is some slight chance that this might fry something. If the
connector is indeed a serial port, this should not happen; even if the
pinout is nonstandard, the spec says that any pins or combinations of
pins may be shorted together indefinitely without damage. But it might
not be an ordinary serial port, or it might be misdesigned. If you're
paranoid you might use a resistor of 100 ohms or so rather than a dead
short for this - and/or maybe try measuring voltages first; if any
voltage is more than about 25 volts either way relative to the
connector shell, either it's broken or it's not an ordinary serial
Once you have that, then I'd measure voltage on pins 2 and 3 relative
to pin 7. If one is hovering around zero and one is higher than about
five volts, then the former is the input data and the other is output
data. If both seem to have high (> 5V or so) voltage on them, then
measure again with a resistor of maybe 100 ohms or in parallel with the
voltmeter. If that still doesn't show one of them driven and one of
them not, it is, again, beyond the scope of this email.
Then repeat the same thing on the Sun (except skip the bit about
shorting pins 2 and 3 to test, since you don't have any way to tell
whether that's looping stuff back), and wire up the connectors so pin 7
is connected to pin 7, and each device's output pin is connected to the
other's input pin. That may be enough to get you going; three-wire
cables carrying pins 7/2/3 are enough a lot of the time.
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