If you are installing SQL Server 2012 on Windows 7 or on Windows Server 2008 R2, you will need Service Pack 1 (SP1) before you can proceed with the installation.
In addition, .NET 3.5 SP1 is required if you wish to install Database Engine, Reporting Services, Replication, Master Data Services, Data Quality Services, or SQL Server Management Studio. .NET 3.5 SP1 should be installed prior to running the setup and the installation process will install .NET 4.0 during the setup process.
Windows PowerShell 2.0 is also required before you can start installing SQL Server 2012.