NAME

mem, kmem, null  −  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 using the debugger.  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. Examining and patching device registers is likely to lead to unexpected results when read-only or write-only bits are present. The file kmem is the same as mem except that kernel virtual memory rather than physical memory is accessed.  In particular, the I/O area of kmem is located beginning at 160000 (octal) rather than at 760000.  The 1K region beginning at 140000 (octal) is the system’s data for the current process.  The file null returns end-of-file on read and ignores write. 

FILES

/dev/mem, /dev/kmem, /dev/null