how are appvar files formatted? - Cemetech | Forum

randomguy · 26 Jun 2021 05:47:07 pm

I know how to edit appvars on my ti 84 pce with C programs using fileioc, but how are the actual binary files formatted, because when I open a .8xp file on a computer hex editor, there seems to be a large amount of additional bytes besides the name and data stored in the appvar.

commandblockguy · 26 Jun 2021 05:50:28 pm

Check out http://merthsoft.com/linkguide/ti83+/fformat.html. You can also use convbin to pack and unpack appvars.

randomguy · 26 Jun 2021 05:53:38 pm

are the ti 84 plus ce appvars formatted exactly the same as the ti 83 appvars, or are there some differences?

Lionel Debroux · 26 Jun 2021 05:55:50 pm

For the file format on the calculator side, which seems relevant to you as you mention "C programs using fileioc", I'll let the TI-eZ80 experts reply.

For the file format on the computer side, https://debrouxl.github.io/tilp-linkguide/ti83+/fformat.html is served straight from the source repositories, but for the most part, Merthsoft's mirror should be identical.

randomguy · 26 Jun 2021 06:02:48 pm

oh, is that why cesium shows the filesize to be larger than the data stored in it, because it includes the comment's and the signatures' bytes?

Lionel Debroux · 27 Jun 2021 01:11:52 am

For regular files, the magic number, comment and other pieces of the header, as well as the trailing checksum, are not transferred to the calculator.

JamesV · 27 Jun 2021 04:45:12 pm

On calc the file size is the actual data size, plus 2 size bytes, plus the VAT entry (which from memory is 7 bytes plus the number of characters in the file name).

eg. if you have a file named "abc" with 100 bytes of data, the file size would be 100 + 2 + 7 + 3 = 112 bytes.

I could be out by 1 or 2 bytes if my VAT numbers are wrong, but it's something like that Smile