Common instruction sets of microprocessors include reduced instruction set, complex instruction set, display parallel instruction set, etc. The following statement about instruction set is correct.

The three types of operating systems divided by application areas are () server operating systems and (), where server operating systems generally refer to operating systems installed on mainframe computers, such as Web servers, application servers, and database servers.

The frequency of CPU has main frequency, external frequency, bus frequency and frequency multiplication, the following statement about frequency multiplication is wrong.