Crystals Primer

Chapter 14: The Data Base

14.1: Index to the disk

14.2: Listing LISTs

14.3: Recovering previous lists

14.4: Purging the disk file

The data base is held in the binary file *.DSC, called 'the disk'. This file MUST NOT BE PRINTED. It will grow with use, and cannot be shortened. Instructions exist for recovering space within the disk. See the section DISK for details.
 

The disk index can be examined with

      !\DISK
      !PRINT
          or
      !PRINT      DISK
      !END

The data in a CRYSTALS LIST can be examined with:

      !\SUMMARY LIST n
      !END
     Which sends a brief summary of LIST n to the terminal
 or
      !\PRINT n
      !END
     Which sends a detailed listing to the .LIS file.

Whenever a LIST is stored in the disk, its serial number is incremented. In general, previous lists are over written, but new parameters lists, LIST 5, are always created. Previous versions can be made current or active by 'resetting' to them. This is done either by giving their absolute serial number, or a relative number.

      !\DISK
      !RESET       5       0      -1
      !RESET       5      42
      !END

The first reset steps back one to the previous parameter list. The second reset (which of course superseds the first), makes LIST 5 serial number 42 the current active version.
 

The disc file slowly grows as lists are accumulated in it. Non-currently active lists can be eliminated with the PURGE instruction. Valuable intermediate versions of lists, such as a good trial structure before an experimental refinement, can retained by setting a flag.

      !\DISK
      !RETAIN 5      17
      !END
      !
      !\PURGE
      !END