Re: Laser 128 to CGA is easy

["Joel" <joelbuckley54.nospam.@hotmail.com>]

"Jose Carlos Lord Apple" <aguilar@onixinformatica.com.br> wrote in message
f57a920b.0211070305.5fe2a4dd@posting.google.com">news:f57a920b.0211070305.5fe2a4dd@posting.google.com...
> "Joel" <joelbuckley54.nospam.@hotmail.com> wrote in message
news:<6LSdnflH4-4MDVSgXTWcow@comcast.com>...
> > While the Laser 128 has a 15 pin video port, it is rather different from
the
> > 15 pin video port on a //c.
> > Unlike the //c, it contains all the signals (R,G,B,I,VSync,HSync) you
need
> > to drive a CGA color monitor.
> > Laser sold simple 15 to 9 pin adapters to do just that.
> > I have 2 or 3 in my basement.
> > That and the built-in parallel printer port were real improvements over
> > Apple's design.
>
> I have a Mono CGA monitor (Samsung). It has a DB9 connector only with
> the pins:
> - Ground
> - Intensity (I)
> - VSync
> - HSync
> - Reserved (?)
>
> I did a DB15 to DB9 cable (I have the Laser DB15 pin documentation)
> with this signals. But it doesn't work !!!! I read that the CGA isn't
> an analog RGB, so, it doesn't work. Do you know how can I do this work
> ?
>
> Thanks,
>
> Jose Carlos
> Brazil
>
> I,VSync,HSync

Jose,
see my post on RGB and the Apple ii

I suspect you don't actually have a mono RGB monitor.
While some may think that's a contradiction in terms (black and white color
monitor), they do exist-I have one.
It takes RGBI input and makes it greyscale.
Your don't have the pin #'s listed on your connector.
But an RGB mono needs to have the Red, Green and Blue signals.
If the one you have labeled Reserved is pin 7, then you actually have a
common MDA or monochrome TTL monitor.
This signal is for monochrome digital video input.
Also, this monitor runs at 50hz/18khz not 60 hz/15Khz that CGA does.
It's conceivable that such a monitor might be able to lock onto the CGA sync
signals.
But you have to run something into the video input.
For a test, just run the Green signal (Laser pin 15)
It should enable you to see text.
But trying to display the Apples 15 colors on a digital mono monitor (which
has effectively 3 colors black, white, and bright white)  doesn't work.
Actual mono CGA monitors convert the 16 RGBI combinations into 16 grey
levels.
Joel