When you already have a defined program (and machine in this case) in front of you for review, then you can determine whether or not it will halt
except when you cant
For any computer program with a finite number of states (finite memory) you can determine whether it halts by running it long enough that it must be looping.
For a computer with 16384 states (An 8 state turing machine with an 8 position binary tape. 8 states * 8 positions * 2^8 values that can be on the tape) you can tell if any arbitrary program terminates by running it for 16385 steps. Any program that doesn't terminate in 16385 steps will run forever.