MEM(4) Kernel Interfaces Manual MEM(4)
mem, kmem - core memory
Mem is a special file that is an image of the core memory of the com‐
puter. 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.
On PDP11's, memory files are accessed one byte at a time, an inapprori‐
ate method for some device registers.