4.3BSD-UWisc/man/cat4/mem.4

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MEM(4)              UNIX Programmer's Manual               MEM(4)



NAME
     mem, kmem - main memory

DESCRIPTION
     _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).

FILES
     /dev/mem
     /dev/kmem
     /dev/kUmem























Printed 12/27/86          May 16, 1986                          1