USB. There's not much information because we don't have much information. When you enter the world of USB, regular asm is gone forever. You now enter the world of randomness without reason. There is no debugging, there is no 100% information, you start to involve hardware failures, and stuff can just not work for no reason at all.

Now that that's out of the way, if you're going to do anything serious with USB, you honestly have to start disassembling the OS to see how they do it. To do this, you're going to want to get IDA somehow and then start looking at page 6F as well as page 75. The OS is useful because they actually knew what they were doing, we can only hope to copy them.

For code, the OS is by far the best resource you have. After that, you can start looking at USB8X as well as my Blue2 program I'm going to attach. There's no reason to show you routines here because they are massive and many.

Finally, for the ports, wikiTI was recently updated by Floppus and myself, there's brandonW's notes on USB ports, and finally there's my large text document which I will also attach.

USB isn't impossible, but it is definitely not easy. You will want some kind of on-screen feedback system to report what happens as it happens. I honestly don't care if you copy my console system from Blue2 because it works marvelously. I'll also attach my program that deletes the Certificate of another calculator via usb>silverlink>I/O port. It has some good routines on data sending.

Lastly, yes, you really need to disassemble the OS. Floppus Maximus, Dan E, BrandonW, and I are some of the few people I know of that have done serious USB port work, and we all have OS disassemblies. (If I missed any, tell me)

Those addresses are just stuff the OS uses. You can completely disregard them.

You can certainly use someone else's disassembly, and that's not a bad idea.

USB. There's not much information because we don't have much information. When you enter the world of USB, regular asm is gone forever. You now enter the world of randomness without reason. There is no debugging, there is no 100% information, you start to involve hardware failures, and stuff can just not work for no reason at all.

+1 for dramatic and completely justified statement.

Also, I think DrDnar spent some time with USB, but I could be wrong.