4
On Levels D1 to D8, the computer tries to complete all
the moves of the game in the times specified below. In a
longer game, the computer gradually increases its speed
in an attempt to stay within the allocated time.
Sudden Death levels
D1
5 minutes/game
D2
10 minutes/game
D3
15 minutes/game
D4
20 minutes/game
D5
30 minutes/game
D6
45 minutes/game
D7
60 minutes/game
D8
90 minutes/game
3.4 Beginner levels
If you are a beginner or a very casual player, you might
find that the computer is impossible to beat using any of
the normal playing levels. It is very frustrating and dis-
couraging to get beaten every single time, without ever
having a chance to try out any of your tactical plans.
Therefore, Chess computer has eight special Beginner
Levels. On Levels E1-E8, the computer plays almost
instantaneously on each move. This prevents the com-
puter from using its full power, and makes it possible for
even a beginner to win occasionally. Level E1 is the
easiest, and the computer’s playing strength increases
gradually up through Level E8.
Beginner Levels
E1
1 second/move
E2
2 seconds/move
E3
3 seconds/move
E4
4 seconds/move
E5
5 seconds/move
E6
6 seconds/move
E7
7 seconds/move
E8
8 seconds/move
3.5 Mate Search
If you have a position where there may be a mate and
you want the computer to find it, set the computer on one
of the Mate Search Levels. This computer solves mates in
up to 8 moves. Mates in 1 to 5 are usually found relatively
quickly, whereas solutions taking 6 to 8 moves make take
quite some time. If there is no mate present or if the
computer cannot find a mate, it will sound the error beep.
Change levels to return to normal play.
F1
Mate in 1
F2
Mate in 2
F3
Mate in 3
F4
Mate in 4
F5
Mate in 5
F6
Mate in 6
F7
Mate in 7
F8
Mate in 8
3.6 Training levels
On these levels the computer searches to a fixed depth
(looks ahead a certain number of moves). On Level H4,
for example, it looks at all continuations up to 12 ply (a
“ply” is a move for either side). By the same token, on
Level H8, it looks at all possibilities for the next 16 ply (8
moves for each side).
Note: In certain circumstances (captures, promotions,
etc.), the computer looks beyond the fixed depth ply.
Training levels
G1
Search depth: 1 ply
G2
Search depth: 2 ply
G3
Search depth: 3 ply
G4
Search depth: 4 ply
G5
Search depth: 5 ply
G6
Search depth: 6 ply
G7
Search depth: 7 ply
G8
Search depth :8 ply
H1
Search depth: 9 ply
H2
Search depth: 10 ply
H3
Search depth: 11 ply
H4
Search depth: 12 ply
H5
Search depth: 13 ply
H6
Search depth: 14 ply
H7
Search depth: 15 ply
H8
Search depth: 16 ply
A chess problem
by Samuel Loyd (1867)
RrstuvwxyS
8MmMmMmMm8
7AGmMmlmM7
6MmMmMAMm6
5mMmMmLmM5
4MmMmMmMm4
3mMmMmMmM3
2MmMmMmMm2
1mMmMmMmM1
TrstuvwxyU
White to play and mate in three moves
Enter this position (as described in section 4.7) and set
level F3 or higher. Press PLAY. In a few seconds the
computer will show you the solution: 1 a8=B
(underpromotion to a bishop!). Try the defenses
1....Kf8, 1....Ke8 and 1....Kg8 to see how White mates
on the third move.
3.7 Instantaneous replies
All times given for the different levels of skill are aver-
age times over a large number of moves. Depending on
the stage of the game and the tactical complexity of a
position, the computer may take considerably more (or
less) time on individual moves.
If you have just made a move and the BLACK light is
flashing (or the WHITE if the computer is playing with the
white pieces) this means that the computer is thinking. At
the beginning of a game, however, replies will be instanta-
neous on all levels. This is because the computer is
playing moves that are stored in its Openings Book It
knows a great deal about good openings that chess
masters have discovered over the centuries.
Even in the middle game you may be surprised to find
the computer very often replying instantaneously to your
moves. There is a very good reason for this: while you are
pondering over a move the computer is not idle, it tries to
anticipate your possible replies. If you play one of the
moves the computer considered, then it does not need to
think any further. It just plays the move it has already
computed— instantaneously.
3.8 Interrupting the thought process
If the computer is spending too long over a move you
can interrupt it by pressing PLAY which will cause it to
stop computing and play the best move it has found so
far. This feature is especially useful on level B8 (analysis)
in which the computer will go on thinking until you inter-
rupt it by pressing PLAY — unless there is only one move
it can play or it finds a forced mate.
On the Mate Search Levels, pressing ENTER does not
cause the computer to make a move. Instead, it sounds
an error beep to indicate that it was interrupted before it
