What is the difference between MMU and MPU?

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MMU == memory management unit

It's a part of a CPU (or an external peripheral) that handles things like memory segmentation and protection, virtual memory paging, etc. Basically it sits between the CPU itself and external memory and translates virtual memory addresses produced by the CPU into physical memory addresses and raises an exception when there isn't a valid mapping for the requested operation and address.

MPU == micro processor unit

The rest is left as an exercise for the reader...

"Neworks" a écrit dans le message de news: snipped-for-privacy@posting.google.com...

hi,

As far as i know, MMU are more complex than MPU. MPU only offer access management over memory areas (depending on running level, some may be set not accessible), whereas MMU enables you to create virtual memory spaces. With MMU the logical mapping differs from physical mapping, and depending on the complexity of the MMU it may be possible to make a fragmented set of memory chunk look like a continuous area, or do some swapping with mass storage device. MMU also checks access stay within defined context limits. The little drawbacks for MMU are quite bigger memory description tables and maybe some increased access delay, power consumption and costs.

hope this will help!

PY

"BiLL" a écrit dans le message de news:ovToc.44888$ snipped-for-privacy@nntpserver.swip.net...

I assumed you were talking about Memory units I went across a MPU concept, as memory protection unit, while working on secured microcontrollers for paycard systems

sorry if the real question was processing unit vs. memory unit.

PY

;-)

Sometime also

MPU == Memory Protection Unit

Handles only memory protection and often is limited to a few regions.

Memory Protection Unit prevents a user application from accessing memory regions own by OS.

Memory Management Unit can do the same thing, but it also provide virtual memory (mapping of logical memory to a physical memory based on memory base offset defined by OS). In this way, a user program don't have to be loaded into a fix location in the main memory. It can be loaded and execute from anyway in the system memory, and the MMU can do the memory translation during program execution.

Joe