what about the 8259 Programmable Interrupt Controller (PIC)?

It seems to be a very handy way to handle multiple interrupt sources. It maps 8 interrupt sources onto one micro-processor/controller interrupt pin. It might be best for 8051 type devices. In fact it is as common a peripheral as the
8255.

Basically what it does is it multiplexes many interrupts onto 1 pin using a sort of 'selector' bus to resolve which source is calling for attention

So if say interrupt #5 occurs, it is 1st picked up by the 8259. The 8259 then enables the 8051 interrupt pin. In the 8051 interrupt handler, you have written a subroutine which then polls the 8259 data bus to check what sort of an interrupt it is. The 8259 outputs the code for "#5" on its data bus, which ur subroutine then resolves internally to vector to the required subroutine-

org 01bh ;interrupt handler vector
mov a,p1 ;8259 data bus on p1

cjne a,#01,chk_int2
sjmp int01 ;if int type 1 goto int01

chk_int2:
cjne a,#02,chk_int3
sjmp int02 ;if int type 1 goto int02

chk_int3:

...and so on

It is YOUR responsibility to program both the 8051 and the 8259 to respond the way u want them to

Alternatively u could implement the whole thing using a basic 8:1 selector/ multiplexer IC (like the 714151), but the 8259 offers many programmatic advantages such as internal priority selection and stuff

kundi