Re: Second Sight Card

[supertimer@aol.com (Supertimer)]

spec@vax2.concordia.ca (Mitchell Spector) wrote:

>In article ab3189@wayne.edu (Charles A. Plater) writes...
>
>>2) How do the finder and other non-secondSight aware applications look when
>>displayed via the Second Sight?  Are things stretched out so that they don't
>>look right?
>
>    Well it reads the SHR video data and then shadows it to the Oak
>chip, redrawing the graphics from scratch on either a 640x400 or a
>640x480 screen. For one things graphics will draw _slowly_ as the
>card is not able to keep up (I recall people saying they could see
>the screens being drawn in the Finder, even with an accelerator!).

Not even with an accelerator, only with an accelerator.  On a stock
GS, the Second Sight is fast enough to redraw the Finder correctly.
On a stock GS, only games cause it to go choppy.  On an Apple
IIGS that has an accelerator, the Finder screen is drawn to fast for
the Second Sight to keep up.  That's why you see a choppy display
when you pull down menus.

If there was more support for the Second Sight's extra modes, the
choppiness is a small price to pay, but if you are going to use the
card for simple VGA display of existing modes, a simple scan doubler
would be have been a better solution.  Instead of shadowing the screen,
a scan doubler would grab each scan line and display it twice.  The
Amiga has them, the Atari ST has them, the GS should have them
too.