Re: A83: Converting TI-83+ Flash ROM upgrade to binary

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Re: A83: Converting TI-83+ Flash ROM upgrade to binary


In accordance with the prophecy, Jeff Tyrrill uttered:


> The new version of Virtual TI supports TI-83+ emulation, so I tried using
> TI's Flash ROM upgrade file (base112.hex), until I realized it was in hex
> and wouldn't work. So I wrote a program to convert it to binary, and filled
> the file with 0's until the length was 256*1024 bytes. Then, VTI would
> recognize it, and display it in the list of ROMs as TI-83 Plus version 1.12,
> but it won't run; VTI just displays a blank TI-83+ screen and appears to
> freeze.

> To convert the hex file to binary, my program read the Base112.hex file and
> processed all the lines of length 75 (it skipped over the rest), then
> skipped the first 9 bytes of each of those lines so there were 66 bytes to
> process, and then converted each dual-byte hex code to a single binary byte
> and placed it in the binary file. Only 236742 bytes were filled that way, so
> I filled with 0's up to 262144. Obviously the encoding method is more
> complex than the above; it appears that the first 9 bytes of each line
> indicate perhaps the location of the hex string in the assembled ROM, but my
> program just assumed all the lines were in order, which they probably
> weren't. However, I did find calculator text inside the binary file I
> created (such as various TI-83 commands), so I know the file isn't
> encrypted.

> So, is there an easy way, or an already available conversion program, to
> convert the TI's 83 hex ROM file to binary format so VTI can use it?


That sounds a bit like the IntelHex format. I think every line begins with
some kind of memory location, and ends with a checksum. You should be able to
find info rather easily, searching for IntelHex somewhere.

Linus

   - Linus Akesson ------------------------- http://linusworld.cjb.net -
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                 I think it would be a good idea.
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