21 Jul
2005
21 Jul
'05
6:50 p.m.
On Wed, 20 Jul 2005 19:26:52 -0400
"Bob Shannon" <bshannon at tiac.net> wrote:
Actually several other pins are active. The token
ring card can tell
when no cable is installed, so there are at least 2 cable detect pins.
Most likely
it determines this by measuring the impedance of the two
coax connections. But I may be wrong here.
At least I know from some DECstation and VAXstation framebuffers that
they report an error at Power On Self Test when no monitor is connected.
As these framebuffers use 3W3 they have no extra pins for cable
detection. They measure somehow DC impedance, AC waveform or the like to
detect an open wire.
--
tsch??,
Jochen
Homepage: http://www.unixag-kl.fh-kl.de/~jkunz/