V4/usr/man/man4/mem.4

Find at most related files.
including files from this version of Unix. 
.th MEM IV 8/24/73
.sh NAME
mem  \*-  core memory
.sh DESCRIPTION
.it 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 using the debugger.
.s3
A memory address is
an 18-bit quantity which
is used directly as a UNIBUS address.
References to non-existent locations cause errors to be returned.
.s3
Examining and patching device registers is likely
to lead to unexpected results when read-only or write-only
bits are present.
.sh FILES
/dev/mem
.sh BUGS
There should be another
.it mem
file that looks at core using the system's address map.