The module Reset switch is connected to a 10K pull up resistor and ZDI interface, which then goes through an OR gate with the JTAG reset then through a buffer. The output of the buffer connects the TVCC_RESET pin of the JTAG interface with a 1K pull up to the reset pin of the eZ80.
The development kit user manual has the schematics for the development kit:
eZ80F91 Modular Development Kit User manual
This arrangement allows for the reset to be generated by the JTAG, ZDI or switch. Depending on when you want the attached device to respond to a reset would dictate where you would interface into the reset circuit.