The first-generation programming instructions were entered through the front panel switches of the computer system.
This makes the language suitable for the understanding of the machine but far more difficult to interpret and learn by the human programmer.
The main advantage of programming in 1GL is that the code can run very fast and very efficiently, precisely because the instructions are executed directly by the central processing unit (CPU).
One of the main disadvantages of programming in a low level language is that when an error occurs, the code is not as easy to fix.
Modern tools such as native-code compilers are used to produce machine level from a higher-level language.