MEM(4) 1986 MEM(4) NNAAMMEE mem, kmem - main memory DDEESSCCRRIIPPTTIIOONN _M_e_m is a special file that is an image of the main memory of the computer. It may be used, for example, to examine (and even to patch) the system. Byte addresses in _m_e_m are interpreted as physical memory addresses. References to non-existent locations cause errors to be returned. The file _k_m_e_m is the same as _m_e_m except that kernel virtual memory rather than physical memory is accessed. Only kernel virtual addresses that are mapped to memory are allowed. The file _k_U_m_e_m also refers to kernel virtual memory, but may be used to access areas mapped to UNIBUS address space and other I/O areas. It forces all accesses to use word (short integer) accesses. Examining and patching device registers is likely to lead to unexpected results when read-only or write-only bits are present. On VAX 11/780 the I/O space begins at physical address 20000000(16); on an 11/750 I/O space addresses are of the form fxxxxx(16). On all VAX'en per-process data for the current process is UPAGES long, and ends at virtual address 80000000(16). FFIILLEESS /dev/mem /dev/kmem /dev/kUmem Printed 7/27/90 May 1