LZ: Link Protocol


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LZ: Link Protocol



I have some information I'd like to share with this group.  The topic of the
info is the gray link cable made made by TI.  I know it's hardware, but
please bare with me for a moment.  You may find it very interesting.

I bought the link cable from Staples last week.  So,  the hacker that I am,
I ran a terminal program (Procom), connected my calc, through the link
cable, to com 1.  I then tried to send something from the calc to the
terminal.  I managed to display the packet from the calc on the screen.  

The packet was in raw ASCII format. When converted to hex, it was the same
as in the Protocol Docs for the TI.  I had the terminal set to monitor mode,
9600,N,8,1.  All hardware handshaking is off.  So then, I connected a
protocol analyzer between my compter running TI's link program amd my calc.
I sent a group file of everything to computer.  The protocol analyzer was
set to auto setup.  I was able to see every packet sent between the two.   

The protocol analyzer returned the following setup:  
Protocol:  Charater
Code:  ASCII 8
9600 bps
Party: none
Async: 1
LSB first

I opened every pin connection in the link except for the following pin numbers:

1: shield ground (may not need this)
2: TX
3: RX
7: Signal ground
20: DTR

The link cable is being power from the TX line.  I traced it through a
diode, caps, then to a small voltage regulator and then to the VCC pin on
the microcontroller.

Well, some of you may have known this info already or not.  Anyway,  you
folks are the ones who can use this info towards writing com programs for
the 85 or 92.   Only two things are needed to make the  gray link cable the
interface to a modem or any other RS 232 type link,  power and software.  

I'm planning to try one of the chat programs next, with my terminal program
and the 85.  It will be interesting to see what happens.  I'll let you know
what I see.

So...what do you think?


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