I'm very new to all this graphing calc stuff so this is probably a noobish question...

Some games give me an error "ERR:SYNTAX" when I attempt to run them. This happens with quite a lot of games so I think I'm trying to run them in an incorrect way or something like that. Do I need to do something else than selecting the program, pressing Enter, and then Enter again? From what I've read, I need a shell for some games, but some of the games that have the "ERR:SYNTAX" error were described as games that did not require a shell...

Help, please?