[net.micro.atari] 520ST video outputs

bryan@ihnet.UUCP (b. k. delaney) (01/15/86)

There seems to be some confusion as to the video outputs of the
520st.  ALL of them have the following:

70hz  Monochrome 
Analog RGB 
Provision for tv modulator.

If you have ever opened up your ST and seen the area where something
is missing, it is the video modulator that is missing.  All Atari is
doing is putting in the modulator back into the ST. 

You will still be able to use the 70hz monochrome monitor and the 
Analog RGB monitors with the mass market ST.


				ihnet!bryan
				Bryan DeLaney
				

knudsen@ihwpt.UUCP (mike knudsen) (01/16/86)

> There seems to be some confusion as to the video outputs of the
> 520st.  ALL of them have the following:
> 
> 70hz  Monochrome 
> Analog RGB 
> Provision for tv modulator.

What about 60Hz (standard) monochrome?
Baseband NTSC composite (what is fed to the modulator)?

> If you have ever opened up your ST and seen the area where something
> is missing, it is the video modulator that is missing.  All Atari is
> doing is putting in the modulator back into the ST. 

Good, I successfully predicted the use for that blank space in an
earlier posting, tho some folks probably wish it were the power supply.

> You will still be able to use the 70hz monochrome monitor and the 
> Analog RGB monitors with the mass market ST.
> 
> 				ihnet!bryan
> 				Bryan DeLaney

Good, but we need 60Hz monochrome (WITHOUT the 3.58 MC color
subcarrier).

Will all these options be on the Preferences screen?  Hope so.
	mike k
	

info-atari@ucbvax.UUCP (01/16/86)

Presumably the "analog RGB" output is synced at 60 Hz, else very few RGB
monitors would work right on it.  Or is there a way to select (there must be)
a 60-Hz output?  If so, then it wouldn't be too hard to whip up a composite
video signal from the RGB, or even a 60-Hz monochrome one.  On the other hand,
a 60-Hz composite signal must exist at the video modulator input, so it could
also be sneaked off from there.  Then at most a low-pass filter would be
needed to feed a 60-Hz monochrome monitor, and in fact the composite signal
could probably be used, as it was designed to be more or less compatible.

Does anybody know whether the whole thing shifts gears to 60 Hz when you plug
into the RF modulator jack?  Or can you simultaneously run RF at 60 Hz and
monochrome at 70 Hz?  This may be the key to why you can't run both monochrome
and color monitors at the same time -- if in fact you can't.

						-John Sangster
						jhs at mitre-bedford.arpa