> This brings up another question. Most of the past year I've spent at
> a client location with my 2400 connected to an external monitor and
> keyboard. The monitor they gave me was a 17 gateway thing. Perfectly
> ok. BUT when it was plugged into my 2400 and you hit the monitor
> control strip, the first line correctly displayed the model and
> number of the monitor!
>
> I understand that the reason Apples monitor connectors are larger
> than standard VGA connectors is because they contain "sense pins"
> that allow the Mac to know what resolutions the monitor supports. But
> in this case there is only a standard VGA connector with none of that
> voodoo, and Gateway sure doesn't support apple sense technology.
>
> How in heck does my 2400 know the model number of the monitor it was
> connected to?
Even though the Apple connector is bigger (a standard DB-15), it contains
the same number of pins as the standard VGA connector (a high density
DB-15). Apple had the foresight, with the introduction of the MacII in 1987,
to make their display adapters "smart", and they were able to determine the
resolution of the connected monitor by looking at various configurations
(open, tied to ground, tied together) of a number of sense pins on the
monitor cable.
All this was fine and dandy until the proliferation of the so-called
"MultiSync" monitors that did not necessarily have fixed resolutions. All of
a sudden the amount of information that needed to be told to the computer
about the supported resolutions and sync frequencies was much greater than
could be conveyed with the tri-state configuration of just a few pins. Just
about this time (only 5 years later or so), the PC world was beginning to
see the light and started pushing the "Plug-and-Play" standard which took
one step beyond what the Mac standard allowed. For monitors, this meant that
information about the monitor, its manufacturer and model number for
instance, would be transmitted digitally to the computer. The computer would
then look up the monitor's specifications in its database and only allow the
user to select supported modes.
Nowadays the Mac also utilizes the same information, which is how it knows
if it's connected to an AppleVision monitor, an AppleVision AV monitor, a
video projector, a Gateway Monitor, or what have you.
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