TwoStep

TwoStep is an esoteric programming language where each statement consists of two characters: a command character and a single digit (or other character). There are 12 commands, and it uses digits 0-9 and a single byte of memory.

Examples
This program prints out "Hello, World!" Notice the comment at the beginning. H e l l o,  W o r l d ! *0+6*2*6[ *0+5*5*4+1[ +7[ [ +3[ *0+5*9-1[ *0+8*4[ *0+5*5*4+9+2[ +3[ -6[ -8[ *0+8*4+1[.

This program runs an infinite loop that prints out "x". *0+6*4*5[ )0.

This cat program outputs its input. ] [.

It may be possible to create a quine in TwoStep, if you can manage to run the following program using the same byte of memory the program is stored in. However, this program only uses a single character, instead of the required two, for the statement. [