8 Sep
2007
8 Sep
'07
1:29 a.m.
On 08/09/2007 00:46, Mr Ian Primus wrote:
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
computer expecting to get from these three lines if
everything is OK?
They're TTL open-collector signals, same as the rest of the QBus.
The LTC is a square wave at line frequency used for a real-time clock.
DCOK is an active-high signal indicating that the DC power is available
to run the processor. It's derived from the regulator output and when
the power isn't OK, it's pulled low. POK is derived from the AC input
and is also high when everything is fine. It's pulled low when the AC
power disappears and is used to initiate a power-fail trap on the
processor, shortly before the DC power is lost.
--
Pete Peter Turnbull
Network Manager
University of York