Re: AST Visionplus

[Wayne Stewart <waynes@intergate.bc.ca>]

"Michael J. Mahon" wrote:

> I was looking over my AST VisionPlus board last night, and I'm becoming
> very curious about how it works and how it should be calibrated.
>
> First, how it works:  I don't see any RAM on the board, so the actual
> storage of video samples must be in the Apple's RAM.  But if it is a
> frame capture board, that means that the whole frame must get sampled
> in real time.  Assuming 256x200 pixels (or so) that adds up to over
> 1MB/s, the bandwidth of the Apple expansion bus--even at only one byte
> per pixel, which I think is low for the 12-bit color it is capable of.
>
> So what gives?  Does it actually require multiple frame times to
> capture a frame?  (If this is the case, then a still image should be
> sampled much better than a moving one, although I hear that it does
> a good job on live video.)
>
> Second issue:  calibration.  The card has two jumpers, a variable
> capacitor and a variable inductor, and five trimpots.  What do these
> adjustments control, and what is the procedure for calibrating the
> card?  (I have an oscilloscope and can find a signal generator, but
> I need to know the procedure.)
>
> Does anyone have the documentation for this card, and possibly even
> the service information?  I'd be happy to pay for copying.

I've got the owners manual but it's the AST manual which was only
included for installation purposes. Since they changed the firmware
and software, I'm not too sure how much of the specs are still relevant.
While they talked about putting out an Allison manual, I never heard
of anyone actually receiving one
I took a look through the manual I have but didn't see any mention of
the jumpers or trim pots. It mostly deals with installing the card and
using the software.

    Wayne