How to change an app's name

[mr. sir]

How do you change an app's name? I have songs I want to simultaneously have on my calculator and I use RealSound to get them on there, but the app is always named "RealSnd.8xk" no matter what I change the name to. I tried opening the file with notepad and changing "Realsnd" to some other 7 letter name, but now the app won't send even if I change it back to RealSnd. Is there some checkdigit-type thing going on?

[FloppusMaximus]

You probably corrupted the header somehow by trying to edit it with Notepad; for doing things like that, you should use a hex editor. In any case, the name in the TIFL header doesn't make any difference to the calculator. It's the name stored in the app itself that matters, and to change that you need to recompute the app signature.

I wrote this program a while ago when somebody else asked the same question. It's based on an older version of RabbitSign (1.2, I think) but as far as I know it should still work just fine.

This program won't resize any of the header fields, so it won't let you replace a short name with a longer one. Doing that (or anything else requiring header fields to be resized) may be possible in many cases, but not in general, and should probably be done by hand.

[brandonw]

To answer the question "What about renaming it oncalc?", before it comes up:

It's possible to back up the sector containing the base page of the application you want to rename, erase it, and then write it back with a new name (provided there's enough space reserved in the app header to make that happen, and since TI recommends that you pad the application out to 4080h (at least) and also that the app name stays 8 bytes and padded with spaces, that's probably not going to be an issue with most applications).

The problem, however, is signing it oncalc so it's valid when transferring it to other calculators. I wrote a program which re-signs the OS and fixes its checksum at http://brandonw.net/calcstuff/resign.zip , and the same thing (or something very similar) could be done to a Flash application to re-sign it oncalc. However, it takes THIRTEEN MINUTES to run. But if that's a sacrifice you want to make to rename the application oncalc, have at it.

[FloppusMaximus]

Neat. I don't think I've seen that program before. Looks like you're using the boot code multiplication routine - it would probably be a bit faster if you wrote your own. :)

Also, signing an app requires only two ~256-bit exponentiations, rather than the one 512-bit exponentiation required for signing an OS. Even without improving the algorithm, that should make it almost four times as fast. So it's not completely unreasonable to think of signing apps on-calc if you really wanted to.

[brandonw]