The main question: why 8 interrupts ???

I have never seen an application, which need so many damned fast interrupts, since then the 8051 was unable to serve all these simultaneous.

I have only seen many slow signal sources, like keys, contacts, encoders, light sensors and so on.

But these all must never be handled damned fast, so polling as many inputs as you want inside a timer interrupt was always a sufficient solution.


Nevertheless, if you really need damned fast reaction (around 10 cycle fast), the standard 8051 support already 5 interrupt sources, the 8052 support 7 and e.g. the AT89C51RD2 support 12 interrupt sources, which all can be triggered from external signals.

But again, I found never any reason to do so.


Peter