[net.micro.atari16] Video out on 520 and 1040ST

olson@endor.harvard.edu (Eric Olson) (06/18/86)

Its my understanding, after reading all kinds of electronic and non-electronic
info about the 520 and 1040ST, that:

- Initially, the 520ST had an analog RGB and non-standard hi-res B&W video out
- Future (and current) 520STs have a composite video out and an RF modulated
  video output.
- The 1040ST has only the analog RGB and non-standard B&W video out

I have also read one comment that seems to indicate that the 1040ST has
composite video on some pin, but not brought out to a video jack.

QUESTIONS:

1) What resolution modes can be displayed through the composite video out?
2) What resolution modes can be displayed through the RF Modulated output?
3) Is there really composite video on some pin of some connector on the 1040ST?
4) Since I must have composite out for my application, what is the difference
(besides cosmetic) between a 520ST upgraded to 1 Meg & 2 DS Drives versus a
1040ST with a DS external drive?  Will they both run the hard disk?

Thanks muchly.

-Eric

neil@atari.UUcp (Neil Harris) (06/19/86)

In article <22@harvard.UUCP>, olson@endor.harvard.edu (Eric Olson) writes:
> 
> 1) What resolution modes can be displayed through the composite video out?
> 2) What resolution modes can be displayed through the RF Modulated output?

The answer to both is the same: both low and medium resolution will be
displayed through the composite, Rf, and RGB outputs.  Unless you have a
_wonderful_ TV set, picture quality of Rf in medium resolution is not too
great (TV's don't have enough bandwidth).

> 3) Is there really composite video on some pin of some connector on the 1040
ST?

No.

> 4) Since I must have composite out for my application, what is the 
> difference (besides cosmetic) between a 520ST upgraded to 1 Meg & 2 DS 
> Drives versus a 1040ST with a DS external drive?  Will they both run the 
> hard disk?

They are the same!  Both will run the hard disk.
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jhs@disunix.UUCP (06/24/86)

If you have a 520 with RF modulator output, you should be able to add a
composite output fairly easily, as the baseband input to the RF modulator is
precisely the composite signal.  All you have to do is bring it out, possibly
with an amplifier stage if the level is not right.  More likely just a switch
or a parallel tap off the input to the modulator will work fine.

I haven't seen the schematic, but you may also pick up some resolution on the
composite output by removing a "slowdown" capacitor put in to keep the TV
modulator bandwidth down.  Or, you might be able to leave such a capacitor in
place and pick off your signal before the slowdown circuit has affected it.

Good luck.

-John Sangster
jhs@mitre-bedford.arpa