TI-85 Link

TI-85 Link

• To: CALC-TI@LISTS.PPP.TI.COM
• Subject: TI-85 Link
• From: Steve Parkis <parkiss@ANV.NET>
• Date: Tue, 30 Dec 1997 18:36:56 GMT
• Distribution: world
• Followup-To: poster
• Organization: All USENET -- http://www.Supernews.com
• Reply-To: Steve Parkis <parkiss@ANV.NET>
• Xref: paladin.american.edu bit.listserv.calc-ti:19432

Has anyone figured out the physical layer of the TI85 link port?

In fooling around with my o'scope it seems I'm seeing the following
when the calc is initiating transfer:

With respect to base band of plug, middle band (which was at +6V in
idle state) fluctuates +6V to 0V as if serial data signal is being
carried.  I see from the $4 serial link schematic that this band
is connected to DSR--is DSR the 'serial input' path for link85.exe
and such?

Again with respect to base band of plug, tip band seems to stay at
a solid +6V...maybe indicating something like DSR or CTS?

This seems odd...the normal idle condition for RS-232 is
nominally -12V, but the calc seems to be using +6V instead.

Would greatly appreciate any info, especially on how data gets to
the calc (which band, etc.), since I can only see outgoing with the
setup I have.

Thanks,


Steve

Request reply by mail in addition to post...my news server derails a lot...

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