but we aren't allowed to write our program in such a language and then compile it aftwards to assembler (which I think is really stupid). So the program needs to be written in assembler.
That is not "stupid" at all. There are enough Cidiots trying unsuccsefully to master the '51 (and other small micros) while totally refusing to acquire any knowledge about the device. The uC world is totally different from the PC world where you just say "if it does not fit, get more resources". Also, in the PC world you access "drivers" not the hardware, with the uC, if you do not know the hardware, you can not access it (efficiently and reliavbly).

There is absolutely nothing wrong with using C for programming a small miocro, I do it 90% of the time, but if you have no understanding of the unit you work with (a lot of which can be acquired by writing some assembler) you will never be able to use the uC efficiently.

Erik