The Unixsystem call which establishes a mapping between a range of addresses in a USer process' s address space and a portion of some "memory object" (typically a file, one of the special "devices" /dev/mem or /dev/kmem or some memory-mapped peripheral). This allows the process to access a file at random byte offsets without USing the seek system call or to access physical addresses or kernel' s virtual address space. It can also be USed as an alternative to writing a device driver since it is USually simpler to code and faster to USe. (1995-02-14)