Re: Help! QuickCam on printer port

Frederick Chu (f.chu@ucl.ac.uk)
Mon, 16 Jan 1995 05:51:30 -0500


Hi all,

Thank you very much to all those who replied. I have now received a message
from Connetrix which I copy below:

----------------------------
>Date: Fri, 13 Jan 1995 16:57:18 -0800
>To: f.chu@ucl.ac.uk
>From: Tech Support <Tech_Support@connectix.com>
>Subject: RE>QuickCam to printer port

> Reply to: RE>QuickCam to printer port
>Fredrick -

>I don't think you're going to like my answer. Basically, your set-up requires
>3 serial ports, and you only have 2.

>Your modem uses the modem port, so QuickCam can't go there.

>AppleTalk (for ARA) keeps the _logical_ printer port active (even though the
>_physical port is empty), so QuickCam can't go there, either.

>We're working on a software change to address the printer port problem, but we
>have to be very careful about it - we can't just blast over the printer port,
>in case it actually is in use by AppleTalk.

>However, even if this were available today, I don't think you'd be happy with
>the overall performance. Your connection to the 610 is limited by your modem's
>speed - for the sake of this explanation, I'll assume it's a 9600 baud modem of
>some sort (even if it were a 14.4 or 28.8 modem, this explanation would be
>pertinent). 9600 baud is 9600 bits per second. One frame of video (160x120
>pixels at 4 bits/pixel) is 9600 _bytes_ of information. Therefore, a 9600
>baud connection would allow you to exchange at most one frame of video every 8
>seconds. Even with a much faster (28.8) modem, this rate would still only be
>one frame every 3 seconds, which isn't enough for videoconferencing.

>With an Ethernet connection between the machines, videoconferencing is quite
>viable - on our Ethernet LAN here at work, we've gotten frame rates over 10
>frames/sec using CU-SeeMe.

>Rob Westergaard
>Tech Services
---------------------------

Thanks again

Fred

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Frederick W Chu, Email: f.chu@ucl.ac.uk
Division of Molecular Endocrinology, Tel: +44 0171-636-8333 ext 3225
UCL Medical School, Mortimer Street, Fax: +44 0171-580-2737
London W1N 8AA, UK.

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