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Backgammon
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Document created by rstuart@ukonline.co.uk on 22nd Nov 99 for
World of Spectrum: http://www.void.demon.nl/spectrum.html

Taken from the CDS compilation 'The Complete Home Entertainment Centre'.

BACKGAMMON gives you the opportunity to test your tactics against a mean
computer opponent across four levels of intelligence. A combination of
cautious defence and risky aggression is necessary to win!

Loading Instructions
--------------------
All the programs will load in 48K Basic mode using LOAD"".

The Game
--------
Backgammon is played by one player against the computer. The player uses the
fifteen yellow counters and the computer the fifteen white counters. The
winner is the first player to get all his counters off the board.

The Board
---------
The board is divided into two identical sides, one for each player,
consisting of twelve elongated triangles, called points, divided by a centre
strip - the bar. The two sets of six points are divided by the bar are called
the inner table and the outer table. The points of the inner table are
numbered 1 - 6, but the numbers are not marked on the board and must be
memorised.

                    BCDEFG A HIJKLM          >>>>      <<<<
                    |||||| | ||||||             |         |
   B-G = 1-6        VVVVVV | VVVVVV             |         |
              INNER                 OUTER    DIRECTION OF PLAY
   Y-T = 1-6        AAAAAA | AAAAAA             |         |
                    |||||| | ||||||             |         |
                    YXWVUT Z SRQPON          <<<<      >>>>
                           |
                          BAR                WHITE    YELLOW

Movement
--------
Your counters must move from your opponent's inner table, through his outer
table, through your own outer table and to your inner table, and then off the
board. The first player to get all his counters off the board wins.
  The first move is decided by the throw of a dice, the highest throw winning
first move. Then two dice are thrown to determine the count for the opening
move, and subsequently for alternate moves. Two counters can be moved at a
time, in which case one counter moves the number of points on one dice, and
the second counter moves the number of points on the other dice. Or you can
move one counter the total number of points on both dice.
  A counter may be moved forwards onto a point not occupied by two or more
of your opponent's counters; if it is occupied the move is blocked and you
must then try to move another counter or counters, but you must move the full
number of points thrown by the dice. If you cannot, you forfeit your turn.

Hitting
-------
A single counter on a point is known as a blot, and if you land on your
opponent's blot, which is called a hit, his counter is taken off the board
and barred, ie. placed on the bar. Your opponent must then return that
counter into play before moving any other counters. To do this he must
obtain a throw from, one or both of the die, that corresponds with a point
from one to six on your inner table, and that point must not be blocked -
occupied by your counters. If, however, he moves onto a blot, then your
blot is placed on the bar.

Bearing Off
-----------
Removing the counters from the board is called bearing off, and you cannot
start to bear off until all fifteen of your counters are in your inner table.
You may then bear off counters from points corresponding to the number thrown
on the dice, or you can move counters within the table.
  You must, if possible, use the full number. For example, if you have a
counter on the six-point and you throw six, you can bear off the counter, but
if the six-point is not occupied you must take a counter from the next
highest point. If a point indicated by the dice is vacant you may only move
counters from a higher point.
  If, while bearing off, one of your counters is hit, and therefore barred,
you must re-enter it as described. You cannot continue to bear off until
your barred counter is back in your inner table.

Controls: General
-----------------
When the program has loaded the board is displayed and set up ready for play.
The dice are rolled to see who moves first; the left hand die shows the
computers score and the right hand die the players'. The highest score moves
first.
  The computer moves the white counters and the player the yellow counters.
If there are more than seven counters on a point, the end counter will be
displayed as purple to indicate this.

Levels: Strength
----------------
The program has four levels for strength of play. These are ranked from 1-4.
Level 1 will play a reasonable strength game quickly, and Level 4 will play
a stronger game, but may take several minutes over complicated moves. The
levels are selected by pressing the appropriate number key.

Change Level
------------
The level of play can be changed by pressing SPACE and resetting the game.

Movement: How to Move
---------------------
A counter is moved by inputting the letter appropriate to the point the
counter is on, combined with one of the dice scores.
  For example: From the initial set up (see diagram) with a score of 3 and 2,
a counter can be moved from N to I, by inputting N3 ENTER followed by K2
ENTER. Before ENTER is pressed a potential move can be cancelled by pressing
DELETE.

Doubles
-------
When a double is thrown, you are entitled to four moves of the number scored.

Bearing Off
-----------
To "bear off" a counter, input the letter appropriate to the point the
counter is on, and one of the dice scores. Which one depends on whether you
are "bearing off" or moving within your inner table (Refer to the General
section on "bearing off" to see whether you can bear off or have to move).

Returning from the Bar
----------------------
When one of your counters has been "hit" by the computer it is brought back
onto the board by pressing Z combined with one of the numbers thrown, which
corresponds with a free point in your opponents inner table. If the numbers
thrown will not allow you to re-enter via a free point then you will forfeit
your turn.

Scoring
-------
Backgammon is also a gambling game, played for a stake, (one point). A losing
player who has managed to bear off at least one counter forfeits the stake,
but if he has not managed to bear off any of his counters he forefeits
double the origional stake - this is called a gammon (two points). If the
loser also has one or more counters still on the winner's inner table, he
forefeits treble the stake - this is called a backgammon (three points).
