Using 8051 interrupt service routines along with the USB interrupts

Question: How to create separate 8051 Interrupt Service Routines along with the USB interrupts?

 

Answer:

All the standard 8051 Interrupt Service Routines (such as INT0#, Timer0 interrupt, Timer1 interrupt, with their corresponding interrupt #) can be placed in a different source file and without having the #pragma noiv at the top of the file. In this case the 8051 interrupts will work without interfering with the USB interrupts (INT2) in the periph.c file.

This is the proper way to create separate 8051 interrupt service routines (i.e. put them in their own source file).