ISa Bus Programming

I an doing a project on ISA Bus and interfacing it with Borland C++ on data capture and using an national cemiconductor’s ADC0816C chip,Help me out o this
How do i write an interrupt service routine with a this language using the IRQ pin availableonthe Same Bus to be activated when the data is ready from the ADC (or the data conversio is complete) so as to be read by the program to the file?