[Mac] 7500 Update

Joseph M Izen (joe@utdallas.edu)
Tue, 10 Oct 1995 17:23:00 -0500

Hi Tim and 7500 owners,
Some progress on the 7500. I have found that the 7500 I am working with
does work with CU-SeeMe and the built-in video board under the following

System 7.5.2
CU-SeeMe 0.83b2
Virtual Memory OFF (you were right about that Tim)

This isn't enough, because Open Transport doesn't keep connections open
longer than a few seconds. I followed the instructions of Mark Hartman
posted to this group on backing out portions of Open Transport. I've
copied them directly from his posting (Thanks Mark!). He was writing with
regard to MacPPP, but they appear to work with ethernet corrections too.

1. Install OpenTransport COMPLETELY.

2. Remove from the Extensions folder the libraries named "Open Tpt Internet
Library" and "OpenTptInternetLib". These are the libraries that have the
code for mishandling dialup connections. Also remove the TCP/IP control

3. Make sure that you have MacPPP 2.1.1SD or later (I use 2.2.0a) and MacTCP
2.0.6 or later. If you don't, they're available in the usual places.

This will permit AppleTalk to operate properly, but will supress OT's handling
of PPP networking.

With this set-up, I can connect up and transmit video, and receive audio/video.

I still have a problem transmitting sound that is stumping me. I am using
the powered mike that came with the 7500. When the sound level exceeds the
transmit threshold, CU-SeeMe transmit only noise, not even slightly
intelligible. Depending on the volume setting on the audio window, it
sounds like fan noise or a jet engine. I can't exclude operator error. I
would be interested in hearing whether other 7500 users can reproduce this
problem, or not. If you think it is operator error, please email
suggestions directly to me at joe@utdallas.edu. I will own up to the
problem publicly if it was my fault once I have a solution, but there's no
point in bugging the PC users with Mac minutiae.

-Joe Izen