Does F23 or F24 support interrupt nesting?

yes, but by default is disabled. To allow nested interrupts please enable it inside each interrupt function where needed.

Hello,

Yes, multiple interrupt servicing (interrupt nesting) is supported.

Multiple interrupt servicing occurs when another interrupt request is acknowledged during execution of an interrupt. Multiple interrupt servicing does not occur unless the interrupt request acknowledgment enabled state is selected (IE = 1). When an interrupt request is acknowledged, interrupt request acknowledgment becomes disabled (IE = 0). Therefore, to enable multiple interrupt servicing, it is necessary to set (1) the IE flag with the EI instruction during interrupt servicing to enable interrupt acknowledgment.

So you basically need to call the EI instruction to allow nested interrupt execution.

www.renesas.com/.../rl78f23-f24-users-manual-hardware-rev100

Thank you for your kind reply. 

 very helpful.