How does microsprocessor work in printer?

Answer 1

Gee, that's an awfully generic question, so you're going to get an awfully generic answer.

In general, a microprocessor, in conjunction with a bit of memory, is used to interpret the data sent to the printer and interpret the language and data contained within in order to compose the page in the page buffer memory. Different printers have different languages. Old Epsons have ECL, HP's have PCL, plenty of other proprietary ones, and of course there's PostScript, the granddaddy of all printer languages (and the most expensive).