This can't be true...

[bieling@terra.es (Jorge Chamorro)]

Apple IIe: Video Signal "NTSC-Compatible", Not "NTSC-Compliant"


I bought Sharp XA305 video recorders to record the video from my Apple
IIe systems: however, I am able to record only black and white pictures.

I tried the same setup with an older Sears model VCR and it worked
perfectly. I tried a new camcorder and got only black and white pictures
again. Sharp told me that this is because the Apple IIe has a
substandard NTSC signal.

Can you help?



The composite video signal coming from the Apple IIe is not stated to be
an NTSC-compliant signal. The signal coming from the video-out port is
only considered NTSC-compatible video. "Compatible" means that generally
the Apple IIe video will work with an NTSC device, although it may not
work in all situations. Specifically, the Apple IIe video signal should
work with all NTSC display devices.

When the Apple II was first designed, economy was of great importance.
The video circuitry was built with as few parts as possible. In the
design process, it was discovered that certain portions of the NTSC
broadcast specification could be omitted, yet still display a color
image on a standard television set. The one element that affects the
described situation is color burst. The Apple IIe does not contain the
color burst element of the NTSC video signal. By modulating other
portions of the video signal, the Apple IIe simulates this missing
information and allows an image to be produced on a television. To
provide a consistent color video image for video tape, this color burst
needs to be present.

In summary, the Apple IIe composite video signal was designed for
display proposes, not for videotaping purposes. The Apple IIe composite
signal is close to the NTSC specification and allows the video signal to
be displayed on television screens. This, however, does not indicate
that the signal can be recorded. Since the signal is similar to the full
NTSC specification, video sometimes records properly on videotape with
certain VCRs. In other environments, the signal may not record at all.
The capability to record a monochrome image falls between these
extremes.

To have a true NTSC signal designed for videotaping, the Video Overlay
Card is required.


Article ID: 5508