Re: Apple ][gs VGA Card

[ntt@cleese.apana.org.au (Jonathan Pratt)]

aar7334@exodus.valpo.edu (AURI MAN) writes:
> 
> Ummm... just for us lamen's, could you tell us what the difference between
> interlaced and non-interlaced is? :)

The video hardware sends a signal to the monitor which is interpreted as
the picture  (simple but true  ;^)

Non-Interlaced = image is sent in its entirety scan line by scan line
until the whole image is repeated and then the image is updated (in its
entirety). This can happen lots of times but typical = 50 or 60 updates
per second which makes for flicker free

Interlaced = the image is sent in two parts (theoretically more but I've
not seen it implemented).  The video signal represents half the screen
each time.  The hardware outputs the signal for alternate scan lines (btw
a scanline = one horizontal row of pixels) all the way down the screen,
and then the next cycle provides the ones in between which were skipped
last time.  This makes the screen update cycle half of the original and
can occasionally show picture abberations like flicker (uncommon) or
aliasing.

cheers
ntt@cleese