                                  Screen #1

- Every question fits on one line. Answer only with keys listed in red on
  the screen bottom line :
  - by a letter, either uppercase or lowercase,
  - by a numeric value,
  - by left or right arrows.

- The programme warns you if you enter a number of samples N too large for
  your PC memory.
  At second line, option "Files" allows to use a N value two times higher,
  but displaying graphics capacity is reduced (see on line Notice).

- The third line controls the visualisation mode of filters by module
  "Graphics", option  "LAST"  : last upstream filter,
              option   "ALL"  : cascade of all upstream filters.

- If you have a virtual disk, give its name to stock temporary informations:
  the programme will save them more quickly.

- Quitting programme is done normally by hitting "q" at the last screen line.
  Then, screen #1 parameters are saved to be reused in the next session.
  During computation, you may end the programme without any saving process by
  hitting Ctrl c, Caps Lock key being OFF and Num Lock key being ON.

- The programme returns to screen #1 after every canal computation. The value
  of module parameters (screens #2 and 3) are unchanged; then you can make
  a new computation with a different value of N, insert a pause between
  modules, etc.

- PGUP key allows to access higher order screens, PGDN key comes back to
  screen #1.

