Sudoku Puzzle ver. 3,0
----------------------
Pavel Zampach (zampach@volny.cz), 2005, 2008


History
-------
3,0  added functions for solving difficult puzzles
2.1  PocketDos compatible
2.0  used puzzle database (SUDOKU.DAT) instead of simple
     generator, facility of typing new puzzles
1.1  bugfixed release
1.0  first public version


Thank
-----
* Curtis Cameron for his excellent graphic libraries
* Tom Almy for ForthCMP compiler
* Angus Johnson for desktop Simple Sudoku program


Installation
------------
is very simple. Copy file SUDOKU.EXE and SUDOKU.DAT to desired 
directory and place link into AppManager or another launcher. 
Needed space is about 64K. Program has to be launched from actual 
directory.
File SUDOKU.DAT contains about 270 simple puzzles. Files 
SUDOKU1.DAT contains 300 simple, SUDOKU2.DAT 300 more difficult 
and SUDOKU3.DAT 600 very hard puzzles. Note, that before use you 
have to rename this additional files to SUDOKU.DAT


Playing
-------
1-9       	enter number into grid
Arrows		moves cursor
F1		help
F2 or <-   	back
F6		switch to computer assist mode
F10       	exit game

If game is interrupted (F10), you can save game and history 
into file (SUDOKU.HST). On next start of program is this loaded 
and game continues.


Computer assist mode
--------------------
In this mode are displayed "candidates" (only points are 
displayed, because HP200LX display is too small to display regular 
digits). As help, small grid is drawn.

F7+number	exclude candidate

F8+number	sets filter, next F8 resets filter. F8+P is 
special pair filter (only cells with two candidates are filtered) 
usefull for "X-Y wing" technique.

F9		sets next filter (none -> 1 -> 2 -> 3 ... 9 -> 1).
When filter is set, corresponding number or "P" is displayed as F8 
label

F4		exclude filtered candidate

F3 has two functions:
1) if in cell is "naked single" (only one possible candidate), 
appropriate value is entered
2) if filter is set, filtered value is entered

F5		solve all "naked singles"


Typing new puzzle
-----------------
1-9       	enter number into grid
Arrows		moves cursor
space or <-	erase number under cursor
F9		end of typing and saving typed puzzle into
		SUDOKU.DAT
F10		end of typing without saving


Game
----
The point of the game is to fill all the grid with numbers 1 up
to 9. You will notice that the big grid has dimensions 9x9.
This board is separated into 9 smaller boards of 3x3. Wihtin
the 3x3 board ALL numbers from 1 to 9 must be placed. The same
number cannot appear in the same column or in the same row. All
numbers from 1 to 9 must appear within each row and each
column.
