v7 man page for mem

MEM(4)							     Kernel Interfaces Manual							    MEM(4)

NAME
       mem, kmem  -  core memory

DESCRIPTION
       Mem  is a special file that is an image of the core memory of the computer.  It may be used, for example, to examine, and even to patch the
       system.	Kmem is the same as mem except that kernel virtual memory rather than physical memory is accessed.

       Byte addresses are interpreted as memory addresses.  References to non-existent locations return errors.

       Examining and patching device registers is likely to lead to unexpected results when read-only or write-only bits are present.

       On PDP11's, the I/O page begins at location 0160000 of kmem and per-process data for the current process begins at 0140000.

FILES
       /dev/mem, /dev/kmem

BUGS
       On PDP11's, memory files are accessed one byte at a time, an inapproriate method for some device registers.

																	    MEM(4)