Memory mapping: Difference between revisions

Revision as of 19:55, 14 January 2006

Revision as of 02:42, 19 January 2006

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'''Memory mapping''' describesis a process whereby some item of digital hardware is connected to a [[central processing unit|processor]]'s address bus and data bus in such a way that it can be accessed (for reading and/or writing) exactly as if it were a memory cell.

This is used as an alternative to connecting it to an I/O port, especially in [[embedded system]]s.

For example, an [[analogue analog-to -digital converter]] could be memory mapped to a certain address. When that address is written to, the conversion is started; when the address is read from, the data is transferred to the processor.

Sometimes only partial address decoding is used, meaning that the device effectively occupies a much larger block of memory space than is strictly necessary. This can be a problem if the memory space is small (e.g. with a 16-bit address bus which can only address 65,536 different locations).