Adding support for interrupts in your programs

When I got back into CPC programming in 2008, I wondered at the time how could I achieve to create a slow graphical effect (taking several VBLs) without caring about the music needing to be replayed 50 times per second. The solution of course was to use interrupts, and this is what this new article is aimed at ! (also added in Articles section).
As usual, I absolutely don't consider myself as an expert, so please if you find mistakes or have suggestions I would be glad to complete the article with your input !