If this is your first ever code on mbed, you should rather go to this code /teams/mbed/code/mbed_blinky/

Here is why: This helloworld source code (which by the way is identical to mbed_blinky) is associated with an older version of the mbed library. Consequently, if you have hardware not yet in the associated mbed library, your program may not compile.

Note: The current library version of this code is https://developer.mbed.org/users/mbed_official/code/mbed/builds/9296ab0bfc11 (The current mbed library is was built on 11/9/2015)

You can see this for yourself by inspecting the contents of the mbed.bld file, which points to the associated mbed library. https://developer.mbed.org/users/cputalk/code/HelloWorld/file/1e30337600e4/mbed.bld

/teams/mbed/code/mbed_blinky/ is the exact same code (except for less comments) but mbed_blinky seems to be managed to always associate with the latest available mbed library version.

If you are the sentimental type who insists on first compiling "helloworld" and your compile fails, use the "update library" feature in the online compiler to update to the latest mbed library version.

I will also attempt to update this fork every now and then. (Latest update 11/11/2015)

If this was helpful to you in any way, please notify me by posting a comment below, because so far I could not convince anyone that this is even an issue.

In a perfect world, I would let Simon Ford (where this code was forked from) update his version of mbed.bld every time the mbed library updates!