simulation of l476 in Keil IDE? What do I need to write on Debug tab?
You can read more about this device here:
https://www.keil.com/dd2/stmicroelectronics/stm32l476vgtx/
honestly it is almost not worth the effort to use the Keil Simulator with this device. The simulator is an instruction set simulator, so does not handle any of the hardware. You will have to fight through the startup code as it tries to setup the PLL but gets no response, etc.
If you want to simulate a Cortex-M4 code, you might try the Cortex-M4 fast model
http://www.keil.com/support/man/docs/fstmdls/
http://www.keil.com/appnotes/docs/apnt_302.asp
that being said, to do what you asked, go to Project -> Options For Target -> Debug, and click the "use simulator" radio button.
You could make a initialization file .ini to script the step overs, you would have to do to get through the simulator. Look at someone using a .ini file in this application note
www.keil.com/.../apnt240.pdf