V7/usr/man/man4/mem.4

.TH MEM 4 
.SH NAME
mem, kmem  \-  core memory
.SH DESCRIPTION
.I 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.
.I Kmem
is the same as 
.I mem
except that kernel virtual memory
rather than physical memory is accessed.
.PP
Byte addresses
are interpreted as memory addresses.
References to non-existent locations return errors.
.PP
Examining and patching device registers is likely
to lead to unexpected results when read-only or write-only
bits are present.
.PP
On PDP11's, the I/O page
begins at location 0160000 of
.I kmem
and per-process data for the current process
begins at 0140000.
.SH FILES
/dev/mem,
/dev/kmem
.SH BUGS
On PDP11's, memory files are accessed one byte
at a time, an inapproriate method for some
device registers.