Breakpoints

In TIS-100, setting a breakpoint requires the player to place an exclamation mark (!) at the beginning of a line. When a breakpoint is set, the program will be paused before that line is executed, allowing you to easily debug code that would be too tedious to step through one instruction at a time.
MOV LEFT, ACC !ADD ACC
MOV ACC, DOW
The program will be paused before this instruction is executed.