MEM(IV)                      8/24/73                      MEM(IV)


     mem  -  core memory


     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





     There should be another mem file that looks  at  core  using

     the system's address map.