Re: TI-H: $4 serial link
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Re: TI-H: $4 serial link
> I have built the $4 serial link and have not had any success in linking.
> I tried it using all of the link software on ticalc. The calc cursor
> stops when I plug the link port into the calc. The led lights. I double
> checked my connections and can't find anything wrong with them.
> Has anyone ever had success in building a homemade link?
Yep.. I've sold about 150 of them. The freezing cursor is caused by the
link cable putting out a logic high signal (0v on the tip/ring with
reference to the collar, because the TI uses inverted logic) which causes
the calc to think a transmission is about to start. So it halts the cursor
and polls the link port, looking for some information. Nothing comes and
the calc doesn't know to give up, so it just sits there.
Oh.. and the 0v signal (rather than the 4.7v or 5.1v that it should be) is
generated before the serial port gets initialized for use by the link
software.
> If so which link and what software did you use?
The serial kind. Parallel didn't work on my last system board and I
haven't tried it yet on my new one. I use link85x with my TI-85. Has
anybody figured out what it is that makes the parallel link work on some
systems but not on others?
> Also, does anyone have any suggestions as to how I can get this link
> working?
If you're using a cable other than the one that comes with the calc (ie
the mouser cable) you'll probably need to take some of the plastic off
around the collar of the plug. This is because the diameter of the plug is
greater than the diameter of recessed port, and the plug isn't getting a
good connection.
> I was forced to use 5.1v zeners instead of 4.7v zeners, would this make
> a difference?
Technically, yes. But it doesn't matter. I've built links with both types
and either works fine. I guess the 4.7v model might be better because it
is closer to the operating voltage of the calc, but the 5.1v works too. I
usually use the 4.7v model for that reason and also because they're less
expensive (I think the difference was about $8 on my last order of 200).
If you're using the serial link on the same port as your mouse and you're
in Windows, either use a different port or exit Windows. If you're using a
port which uses the same IRQ as your modem while your modem is dialed,
close the modem connection.
As for testing, pick a port and plug it in. Get the link85x program and
set it for COM1. Wait six seconds or so to see if the cursor begins
blinking again. If it doesn't, set link85x for COM2 and try again. Keep
going for COM3 and COM4 until you find a match. This will at least let you
see which port the link is really on.
As for software.. umm, link85x is the only program I use. I have an 85 and
this program has never given me a bit of trouble.
BTW, link85x is on my ftp site at
ftp.xmission.com/pub/users/g/gregh/link85x.exe. Login as anonymous and
use your e-mail address as the password.
--
Greg Hill
greg-hill@bigfoot.com
www.comports.com/link
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