Function            read_mode - find screen width, mode and page

  Syntax              void read_mode(byte *width, byte *mode,
                                     byte *page);

  Prototype in        video.h

  Remarks             detects the screen width (number of columns,) video
                      mode and video page via INT 0x10, Service 0x0F.

  Return value        nothing.

  See also            video.h
                      set_mode()

  Example             #include <video.h>

                      main()
                      {
                           byte width, mode, page;

                           read_mode(&width, &mode, &page);
                           printf("# columns: %d  Mode: %d  Page: %d\n",
                                  width, mode, page);
                      }

  Program output      # columns: 80    Mode: 3   Page: 1