Hey all,

I'm making a multiplayer game with 2 calculators, in which I want to share both scores. To do that, I'd like to swap both DE-registers. I figured this couldn't be that difficult, but I do not even know how to communicate with the USB port yet. And since this port wasn't there on the TI-83+ calculator, it's not explained in the ASMin28Days tutorial.
I'd appreciate if someone could help me out with this. Thanks in advance.

Greetings, Arriopolis.

Use CALCnet so that you can have two-or-more player games!

High-level details and video: http://www.cemetech.net/projects/item.php?id=33
Brief programming details: http://dcs.cemetech.net/index.php?title=Interfacing_CALCnet2

Although I appreciate the fact that CALCnet2.2 offers simple communication between calculators, I'd really like to just do it on my own... you know, getting some more coding experience.
My intuition says that it cannot be that hard... something like:
Sending calc:

Code:

Recieving calc:

Code:

Arriopolis, sorry for the slow response. I'm afraid that that is far, far too simplistic. Even ignoring the USB port (which has the more complex semantics between the USB and I/O ports) and using the I/O port instead: there are four things you can do:

1) Pull the tip high
2) Pull the tip low
3) Pull the ring high
4) Pull the ring low

You have no other communication channels, certainly not a full byte, and you have no shared clock. Therefore, you must either use one of the lines as a shared clock, or coming up with a timing-agnostic protocol. To make your life slightly more complex (or slightly easier, depending on your perspective), if either calculator pulls either line low, then that line is low for both calculators until both calculators release it. Pseudocode:


Code: