Sequence of steps performed when opening up a database

After issuing of SHUTDOWN ABORT command, when opening up database following step are performed

1. SPFile / PFile:             Server Parameter file ( SP File ) or the initialization parameter (initSID.ora / PFILE ) file is read
2. Memory :                      SGA is allocated
3. Background Process: Background process are started
4. Control File :                Control file is read
5. Redo Log File:              Redo Log file is read
6. Data File:                       Data files are checked for consistency
7. Instance Recovery:   Instance Recovery is started