Re: [stella] combat scanlines?

Subject: Re: [stella] combat scanlines?
From: "Roger Williams" <mer02@xxxxxxxxxxxxx>
Date: Sun, 4 Nov 2001 09:06:28 -0800
> So if I understand it, the following is is true...  If the a2600 was
> plugged into a television that could display 500 scanlines, a programmer
> could actually display stuff on the entire screen using the standard
> hardware.   And therefore, from an emulation view, we should not make
> assumptions about the start/finish scanline, but use the cartridge coded
> start/end VBLANK and VSYNC to set the beam position?

A TV that could display 500 scanlines would probably choke on
Stella's fixed horizontal frequency.  All TV's make assumptions
about the horizontal to vertical ratio, since they must psychically
figure out at the start of a video frame how fast to pan downward
so that the beam will be at the bottom of the screen when it ends.

While it has gotten cheaper to make TV's that are more forgiving
and can render off-spec sources and do multiple video formats,
most of them still use the horizontal sync to drive the flyback to
generate the high voltage and messing with this timing can burn
out the drive transistor.  From an emulation standpoint I think
it's a really really bad idea to encourage off-spec video timing.

> if thats true, then whoa - is there another machine with this capability??

Fortunately, no.

--Roger Williams

Archives (includes files) at
Unsub & more at

Current Thread