Differences/Changes from Previous Loader

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Summary of main changes

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- Routines   withdrawn: LOAD,   FINDENTRY,   GETUNSATREF,   LOADCOMMAND,
  LOADFILE, UNLOAD, EXTENDSESSIONDIRECTORY.

- New    routines/facilities:     LOADPARM,    DATASPACE,    ALIASENTRY,
  RESETLOADER, LOADEDENTRIES, LOADEDFILES, CURRENTREFS, EXECUTE,  USEFOR
  (all   at   user  level).   LOOKLOADED,  SEARCH,  LOADEP,  LOADENTITY,
  CASCADELOAD,  MINLOAD,  LOADFILE2,   UNLOAD2,   CURRENTLL,   LOADDUMP,
  BDIRLIST (at system level).

- Search order for directories altered.  Subsystem base directory is now
  searched  before the searchdir list (but after the active dir) instead
  of being searched last.

- Concept of LOADLEVEL introduced.

- Loader supports dynamic data references.

- Store mapping for FORTRAN/PASCAL etc. supported.

- PRELOADing fully supported.

- Session directory disappears, replaced by set of loader tables.

- Subsystem entries and Director system call list made shareable.

- Enhanced monitoring facilities.

- Run time parms for the loader now controlled and set by LOADPARM.

- LOADPARM(MIN) will only load those files necessary to  run  regardless
  of what compiler parms were set.

- No limit on number of bound files which can be simultaneously loaded.

- Any  reference  which  arises  to an item which is currently loaded is
  satisfied immediately.

- If a command is typed at command level then the loader will first look
  for an entry point of that name.  If none is found then the assumption
  will be made that the command is in fact a  filename  and  an  attempt
  will  be  made  to  connect  it.  If successful then if the file is an
  object file with a main entry point then it will be entered.   If  the
  file is a character file then OBEYJOB will be called with the filename
  as  a  parameter.   No  action  will  be  taken  if  neither  of these
  conditions apply.  Following from the above  then  object  files  with
  main  entry  points  can  be  run  by simply typing the filename which
  contains the main entry, i.e. at command level  RUN(PROGY)  and  PROGY
  will have the same result.


Suggested replacement routines

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    The  following  are  suggested  replacement  routines  for  the most
commonly  used  system  routines  in  the  old  loader.   Software   can
interrogate  the  subsystem  to  discover  which  loader  is  running by
examining the value of UINFI(26) - a value  of  0  means  that  the  old
loader is running.

    All the new loader routines except LOOKLOADED require as a parameter
the  'local  loadlevel'.   A  call  on  the  system  function CURRENTLL,
described in the loader system interface, will give the current value of
this variable.  This is  the  value  which  should  be  supplied  unless
'permanent'  loading  is  required,  in which case the value is 0.  This
topic is discussed at greater length  in  the  'Technical  Aspects'  and
'System Interface' sections.



FINDENTRY     -> If only interested in material already loaded then
                 LOOKLOADED else SEARCH for complete search
LOAD          -> LOADEP
LOADCOMMAND   -> LOADEP
LOADFILE      -> LOADFILE2
MODDIRFILE    -> If used to modify session directory then no replacement
                 since no session directory, otherwise MODDIRFILE.
UNLOAD        -> UNLOAD2