Curious about Extender History

ti83programmer · Post by **ti83programmer** » Wed Apr 20, 2005 3:59 pm

The more I sit and think about extenders, the more it just amazes me, so I want to ask you guys...how did you find out all these ROM calls like LightOn and LightOff that these remotes use? Did you write a special protocol that blinks out the memory contents and you picked it apart or what? I guess maybe you took protocols from device upgrades and disassembled them and looked for patterns, I don't know, but it's really something.

Nils_Ekberg · Post by **Nils_Ekberg** » Thu Apr 21, 2005 1:26 pm

The toughest part is probably the interface and figuring out how the pins worked on the chip and how to communicate with it from the PC.

One you get to the chip it is really just like any other chip which effectively it is just an operating system that communicates with the remote which is written in assembler language. You dump it and disassemble it. Then it is just a matter of figuring out what each section of code does to the remote. Mostly trial and error and a lot of patience.

I know this over simplifies it but thats basically it.

ti83programmer · Post by **ti83programmer** » Thu Apr 21, 2005 1:54 pm

It's the dumping part that intrigues me...if all you can do is get a dump of the EEPROM, how do you use the interface to get to its operating system?