BA123 power supply signal question

[Tony Duell]

> 
> On a BA123 power supply, each regulator has three
> non-power pins - LTC, POK and DCOK. Am I correct to
> assume these are TTL level outputs? What is the

I'm pretty sure they're open-collector outputs. They can be pulled low by 
the PSU, but are pulled high by a resistor on the bus terminator (maybe 
the CPU in Q-bus systems?)

> computer expecting to get from these three lines if
> everything is OK?

POK = Power OK, and is pulled low by the PSU if the AC input to the 
regulator fails

DCOK is pulled low if the DC output of the regulator is too low. 

In normal operation, both these signals are high

LTC = Line Time Clock, and is a regular square wave. What I can't 
remember is if the frequency is the same as mains (50/60Hz) or twice it 
(100/120Hz).

-tony