Hi !

So, here it is, the DSSI-Powerplug:

I just checked out this cabling, all drives use this wire in parallel. My
multimeter sais: There is logic HIGH level on this. Connecting a LED between
+5V and this pin results in the following:
After powering up the machine, the LED lights up a short time, then goes off.
This means, there is a little LOW-pulse, which then gets HIGH and stays HIGH
all the time. INIT or UNJAM doesn't repeat this phase. Looking a bit deeper
into the hardware revealed this wire being connected to a purple wire from
the power supply. So i just would say: It's a POWER_GOOD signal. This would
fit most for the purpose of this connector, and if it would be RESET, i think,
DEC would have it triggered with INIT or UNJAM also.

If you can't get any kind of POWER_GOOD in your box, you simply can connect a
capacitor and a resistor in the following way:

+5V  -----*------------------
          |
          |
          -
         | |
         | |
         | |
          -
          |
          |
          *------------------ POWER_GOOD
          |
          | +
        -----
        -----
          |
          |
GND  -----*-------------------

Values should be tested, i think 4,7uF and 1KOhms would be nice. This keeps the
signal low some time, only difference to the original is the slow increment of
voltage, someone may want to put a schmitt-trigger between this.

As an alternative, you could hunt for a RESET line, and use this for it. Not
that clean, i think, because this could be triggered several times when powered
up. The drive could then think, what do you want from me?

And finally, here is the pinout of this connector, viewed into the drive's
side, the bar left is the locking tab.

    D - POWER_GOOD
   |# - +5V
   |# - GND
   |D - GND
    D - +12V

Hope, someone has fun with this :-)

[Usual disclaimer, i don't take any responsibility for drives turning at
20.000 RPM after this and so :-)]

...Michael

-- 
 Michael@camaronet.de, Rottweil/Germany, http://www.camaronet.de
 Visit the german VAXpage: http://www.vaxpower.de