Re: [stella] tutorial progress

Subject: Re: [stella] tutorial progress
From: Erik Mooney <erik@xxxxxxxxxx>
Date: Fri, 28 Jun 2002 15:36:16 -0400
6/28/2002 3:17:14 PM, Chris Wilkson <ecwilkso@xxxxxxx> wrote:
>> Has anyone had problems with stuff during the horizontal blank
>> becoming visible?  Or does the TIA make it so the beam is turned
>> surprssed during that time?
>When BLANK is active, the TIA sets all the LUMA lines low, so that the
>"drawn" picture is black.  And depending how things are wired on your
>motherboard, it's actually "blacker than black".  Either way, it isn't

Actually, IIRC from Video Demystified, it's VSYNC that's "blacker than
black", a signal at much lower voltage than regular black.  VBLANK
shows up on a TV the same as writing 0 to COLUBK and urning off
any objects/playfield.  (Try it in the middle of a frame.)

>> it might be hard to represent the time when the electron beam zips
>> back, unless it was much much less than a cycle.
>Don't worry about it.  If you do, you have to give each scanline a
>downward tilt as well.  Like this (exaggerated): \
>Then it just gets too complicated and confusing to be useful.

For the purposes of the Atari, the whole thing really does behave as if
the TV picture is on the right side of the Universal Rectangle.  I
always thought of it that way and never got confused.

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