It depends. I think downgrading can (it did when I downgraded my 83+SE from OS 1.18 to 1.13). It might depend, though.

On Cemetech, BrandonW says it doesn't.

But I suppose downgrading might be different?

Still, though, as long as you can send the OS (and ArchUtil, for that matter), you should be able to use TI Connect or TiLP to make a backup... so I'm still not sure why it would be a problem.

There is apparently a C compiler for the Z80 that supports Z80 calculators, z88dk (I found it when I was reading through the newsletter archives on ticalc.org- it was in the second-to-last one). Here is a link to their forums... I presume some people already know about this, but others might not. I didn't.

Apparently it's not too efficient or easy to use- and most of the posts in the "TI Calculators forum" are bug reports- and they don't have anyone working on the project at the moment who actually owns the calculators. But it appears to still be in active development- last release was in 2009.

Since everyone's listed a lot of ones for the 83+/84+ already, some of these are for other calculators.

67. The first two versions wouldn't have any way of linking to other computers or devices.
68. One of the latest versions makes practically every program written for an older version incompatible.
69. Deleting an application would damage your flash memory.
70. Newer versions would have more memory, but would be cluttered with some useless applications (see 69).
71. The headphone jack, used for communication between computers, is only weakly soldered and can easily break.
72. The latest version didn't support any programming when TI first released it.
73. In order to communicate with it from another computer, you need special linking software that doesn't work half of the time.

Another thing I did a few times: I decided to switch to lowercase letters in some of my BASIC RPGs. BAD idea. I did not realize about lowercase letters being two byte tokens. I eventually ran out of RAM

That reminds me of something I did when I started programming my 89 Titanium- I used spaces to indent lines of Basic code, like in this sample program, and then I'd add additional spaces to anything under a loop or if statement.

hello()
Prgm
 ClrIO()
 Disp "Hello world"
Prgm
Since on the 89 the interpreter ignores all whitespace before code, it didn't cause any problems. Except, each character- including a space- adds a byte to the program size... so the Basic programs I wrote ended up much larger than necessary.

Not that that's so much a problem on the Titanium, since it has so much memory, and it does make the code more readable- but when you realize that for every line under a loop, I would be adding two bytes, and then under an if statement, three bytes, and so on... it could easily get way out of hand.

Well, after trying it (it didn't work), I realized that you can't get the voltage from that when the calculator is open, because there's no power- all the batteries are out, including the backup- so the only power would be from the multimeter itself. (I could only test the resistance of the solder to the port using the power from the multimeter.)

Any other ideas?

Is it possible it's not the link port or the solder, but some bit of wiring in the calculator that provides power to the link port?

Quote from: TC01 on July 03, 2010, 11:34:55 am

The worst GroupTool has done to my calc is reset my lower case flag.

Do you mean that the calc cursor got locked down to lowercase ALPHA, not letting you turning it off? I remember back in the days it happened to some people at school and I always wondered how to fix it without forcing a RAM clear

No, I mean the system flag that defines whether lower case is on or off was reset, disabling lower case on the calculator. It can easily be reset using CalcSys or an assembly program that changes the flag- it was just annoying to have to do each time I used GroupTool.

Well, I've opened up my calculator and taken a look at the link port. But I'm not really sure what to do- from what I can tell, it doesn't look like there are any flaws in the solder around the link port, but I'm not sure if that's the right place to look. Because here is what KermMartian posted on Cemetech:

The times this has happened to me, it's been the relatively simple issue of TI's weak soldering job on the link port failing. The link port is a tiny plastic piece soldered onto the motherboard of the calculator at three points, each corresponding to one of the gold rings on the plug you put in the link port. If you can archive all of your programs to ROM, your best bet would be to do what I did with my very first TI-83, which eventually developed this problem. Open it up (you'll need a Torx-6 screwdriver and also a phillips for the backup battery) and locate the black plastic link port at the bottom of the motherboard. It's not even necessary to unscrew the motherboard for this fix: look closely at the link port and you should notice flaws in the solder on at least one of the pins. Once you find the pin or pins, heat a soldering iron, get some solder, then CAREFULLY melt the solder on the pin and dab a bit more on. Remove the iron after the solder to ensure a good connection. You might want to repeat one at a time for the other two just to be sure. Be very careful not to accidentally hit one of the tiny surface mount components around the port with the iron, as they come desoldered very easily and are nearly impossible to resolder with normal commercial tools. Then seal the whole thing back up and cross your fingers.

Is the flawed solder actually inside the link port- the black plastic piece- or is it around the edge of the link port where the port is connected to the motherboard? I had assumed the latter when I first read this, but now that I've actually opened up the calculator I'm not so sure, as the solder seems to be fine around the edge of the link port.

Has anyone here successfully done this procedure, who could give some more information?

Would it help if I took a picture of the link port and attached it?

Damn thats no good.  Hopefully you have a way to fix it Is there any info on how the port is to be constructed?

I can't seem to find any- the only information I've got to go on is what KermMartian posted on Cemetech in the help thread there.

Although, I did find a tutorial about the TI-83's port, although that mainly talks about assembly programming. And I also found a detailed guide (that does talked about the hardware- it had a circuit diagram) for the TI-85/TI-86's link port here, but I don't know if the hardware of Z80 calculators changed between the 86 and the 83+.

Most of the link port documentation is about how you can do stuff with it using an assembly program, not how the port itself is constructed, it seems.