Hello.

I am working with AT89C5131
I have searched example code to find how to handle external interrupt(INT0)
I have found function like below

--
void keyboard_interrupt() interrupt 7 using 1
{
......
}
--

I have never seen code like above before but this seems to be code I was looking for.
There was no part of code with designate keyboard_interrupt() as interrupt routine
"using 1" seems to mean interrupt number and I have no idea what "interrupt 7" means.
Please help me understand this function definition
This code is compiled well

Thanks.