MEM(4) BSD/hp300 Kernel Interfaces Manual MEM(4)NAME
mem, kmem — main memory
The file /dev/mem is an interface to the physical memory of the computer.
Byte offsets in this file are interpreted as physical memory addresses.
Reading and writing this file is equivalent to reading and writing memory
itself. An error will be returned if an attempt is made to reference an
offset outside of /dev/mem.
Kernel virtual memory is accessed via the file /dev/kmem in the same man‐
ner as /dev/mem. Only kernel virtual addresses that are currently mapped
to memory are allowed.
On the HP300, the last byte of physical memory is always 0xFFFFFFFF.
Therefore, on an HP300 with 8Mb of memory, physical memory would start at
0xFF800000. On the HP300, kernel virtual memory runs from 0 to about
The files mem and kmem appeared in Version 6 AT&T UNIX.
BSD June 5, 1993 BSD