[sizeofchar]

Seems like the same as in multithreaded programming, in which you can’t let threads share memory without synchronizing else you get data races and corruption.

[naikrovek]

it's more like two simple computers talking over serial, and the serial connection bitrate can't be faster than the clock of the slowest of the two computers.

[photojosh]

Yep! The microcontroller reference manual is full of warnings to ensure clock rates are compatible by being within a certain range of each other.