Re: RGB monitor compatibility

[aw133@lafn.org (James Poore)]

In a previous article, ab616@chebucto.ns.ca (Tony Cianfaglione) says:

>
>   The Commodore 128 RGB is digital and won't work correctly for the GS
>because the GS monitor has an odd (scanning or refresh) rate (15.5??).
>The IIc (via a Video 7 adapter) works well with the 128 monitor.  I have
>an old Magnavox RGB which has digital and analog inputs so it could
>accommodate both if the rate was correct which it isn't.  The picture
>comes out a cruddy pale yellow.
>
>   The Atari ST monitor works like a charm (because it, too, uses the
>odd rate) if you can assemble the correct cable as the ST plug is very
>unusual in its shape.  The GS also uses composite sync and most other
>systems use separate vertical and horizontal sync.  I hooked the vertical
>to the composite and it seemed to work alright.
>
Whoa!  The Commodore monitor wont work with the GS because the GS 
has analog RGB!  The Horiz Scan rate for a GS is 15,750Hz jus 
like the NTSC standard.  Even if it were 15.5, it could be 
tweaked to lock on.             
As far as sync goes, normally monitors that have separate inputs for 
Horiz and Vert Sync can use composite sync applied to the Horiz only, or 
both inputs but never Vert only.

As my memory has it, there is pretty much one digital RGB standard but 
analog RGB has as many variants as different computer platforms.

Now as far as hookups go, The IIe has a Digital RGB with an Apple 80 col 
RGB board.  The IIe can also use a video7 which is Digital and finally,]
AE had piggyback boards for the Ramworks Cards (aux slot memory) that 
supported both analog and digital RGB.

The IIgs is analog RGB, and the IIc is digital.

Jim

-- 
James M (Jim) Poore--Apple II's Forever--Especially IIgs's
Los Angeles Free Net---aw133@lafn.org
Here siggy, siggy...Here Boy
Where is that damn SIG?