BBC Turtle Clone?

I was thinking using switch:case would run faster, without have 5 or 6 sets of if:then statements to go thru.
I don't know how to define cases based on two array elements tho.
Somehow make a variable
command = iC[0] + ic[1];
then use that for the cases.
Probably simple, I've just never done that:

switch(command){
case 'PD':
// 
break;
case 'PU':
// 
break;
//etc.
}