--- On Sun, 2/22/09, ChesapeakeTechie <[email protected]> wrote:
> Hi all - I have a IIci and am having some issues trying to
> get it to
> work with a VGA monitor. Picked up a VGA -> DB15 adapter
> (UNIMAC-82D)
> and no matter which dip switch settings I use, I can't
> get an image up.
The IIci uses sync on green and it requires the sense pins to be tied together
correctly to tell it what resolution the monitor is.
There are adapters with DIP or rotary switches to set the sense pins, but the
monitor still must support sync on green.
For monitors that don't supports sync on green, Griffin made a hideously
expensive (around $50 when they were last selling it) that has the switches and
converts sync on green to composite sync or H/V split sync.
Some monitors have the two sync signals combined on one pin. (Composite sync.)
Many PCI and AGP videocards support that, but I don't know of any NuBus cards
that do.
An analog VGA monitor only requires 8 signal pins. 6 for the red, green, blue
signals and grounds and 1 each for horizontal and vertical sync.
Aside from those 8 pins, the rest of the 15 for non-Macintosh uses were unused
until the advent of DDC- Display Data Channel, for Plug n Play.
Some of the earliest VGA and SVGA monitors had a 9 pin connector with a
removable cable to adapt to 9 or 15 pin or Mac 15 pin ports. Some of those also
had TTL modes for use with PC's mono/Hercules/CGA/EGA video. Yet another option
some of those had was the ability to switch amongst the three sync setups. And
still another feature many had were BNC jacks. Unfortunately many of those "do
anything" monitors also had .3 or higher dot pitch screens and no support for
higher horizontal scan rates.
I have one of what must be NEC's earliest MultiSynch monitors. It has no model
designation at all, just "NEC MultiSynch". It has a 9 pin connector, BNC jacks,
does at least 800x600 SVGA and all TTL modes. IIRC it also supports the three
sync methods. It even has a cooling fan. Unfortunately it's rather useless for
modern systems because its maximum horizontal scan rate is lower than the
default minimum of late 20th century to present videocards. Also unfortunate is
the butt-ugly .31 or worse dot pitch. It's like watching a TV through a screen
door. ;P 60hz refresh didn't used to bother me until I got to be around 29~30
years old.
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