Yes, it is (or was) Hauptschule, Realschule and Gymnasium, but many states didn't have a Hauptschule or abolished it.
Now, you go to something like the Realschule and leave it after 9 years to get a Hauptschulabschluss (lowest leven of highschool "degree")
Also, while it sounds harsh that kids have to decide if they want to study with 18 when they're just 10 years old, it's possible to keep going to school after the 10 years of Realschule.
The "Förderstufe" was two years of education where I was put into courses of different difficults to see in which system (Hauptschule, Realschule or Gynasium) I would do better, allowing me to decide when I was 12 (normally you had to decide when you were 10)
Also, the "Fachoberschule" was two years I did after Realschule to get access to university.
So I never went to a Gymnasium and still got to study computer science in the end.
Now, you go to something like the Realschule and leave it after 9 years to get a Hauptschulabschluss (lowest leven of highschool "degree")
Also, while it sounds harsh that kids have to decide if they want to study with 18 when they're just 10 years old, it's possible to keep going to school after the 10 years of Realschule.
The normal ways could look like this:
Elementary School(1-4) -> Gynmasium(5-13) -> University(14-...)
or like that:
Elementary School(1-4) -> Realschule(5-10) -> Apprenticeship(11-13)
But there are many different variations of that.
I, for example, did it like that:
Elementary School(1-4) -> Förderstufe(5-6) -> Realschule(7-10) -> Fachoberschule(11-12) -> University(13-17)
The "Förderstufe" was two years of education where I was put into courses of different difficults to see in which system (Hauptschule, Realschule or Gynasium) I would do better, allowing me to decide when I was 12 (normally you had to decide when you were 10)
Also, the "Fachoberschule" was two years I did after Realschule to get access to university.
So I never went to a Gymnasium and still got to study computer science in the end.