Electronic tennis game

An electronic simulated tennis game is played on a gameboard which includes a matrix of multicolored light-emitting diodes scaled to resemble a tennis court. Each diode is positioned at a grid area and is illuminated to indicate ball and player positions. A keyboard is provided and competing players electronically enter their selected palying positions and the target positions for the ball. There is also provided a scoring display, switches to initiate play and light means which instructs the players as to points and movement results. This tennis game is played on a gameboard which is under the control of a programmed microcomputer which processes each player's inputs according to a simulated tennis game program and displays and computes the results of each player's selections on this gameboard and displays the results as to an error or a successful volley.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to electronic simulated tennis games for use in the 
home or parlor, utilizing an illuminated electronic gameboard, a keyboard 
providing for player interaction, and a programmed memory, introducing 
elements of chance and skill, and implemented electronically by the use of 
digital logic circuits, a microcomputer system and light-emitting diode 
displays. 
2. Description of the Prior Art 
The game of tennis is difficult to simulate in parlor gameboard techniques 
and, therefore, there are few prior patents in this general area. A 
typical toy-type game is disclosed in U.S. Pat. No. 3,904,203, which 
utilizes a ball at the end of a pivoting arm. A simulated parlor-type 
tennis game is disclosed in U.S. Pat. No. 3,933,355. The game of this 
patent uses a gameboard having a scale diagram of a tennis court with 
appropriate positions marked thereon. It utilizes as a random selection 
means three die cubes. It uses three mechanical indicators for ball 
flight, ball bounce and player position. Lastly, it uses a serve and lob 
chart for indicating the results of the first serve, second serve and lobs 
responsive to various combinations of the three die cubes. 
The most recent tennis board game known to the inventor is that disclosed 
in U.S. Pat. No. 4,007,937. This gameboard utilizes a scaled tennis court 
divided into a grid whose coordinates indicate player and ball position. 
Selective cards and tiles determine ball and player positions and markers 
are placed on the gameboard to indicate these positions. The parlor game 
of this patent is one of the most recent and most sophisticated of the 
non-electrical simulated tennis games. 
In the field of electrical and electronic simulated tennis games, the most 
popular and best known are those employing a cathode ray tube or an 
adapter connected to a standard television receiver. These are numerous 
prior patents on these devices and on the subsystems used in these 
devices. An example is U.S. Pat. No. 3,778,058. The assignee of that 
patent is also the assignee in many related patents. 
The simulated tennis games of the prior art have numerous disadvantages. 
The nonelectric gameboard, plus dice, plus chart or card-type games lack a 
sense of realism and action. The physical means are not available for 
anticipating and incorporating all those elements of skill and chance 
which make a real game of tennis hold the interest of the players. The 
video-type electronic games have managed to incorporate speed of reflex 
response, but often at the cost of sacrificing skill and strategy. Thus, 
they also lack the sense of realism. Video-type games also have certain 
other disadvantages. Those which rely upon a standard television receiver 
lack portability. They are fragile and require service. And the more 
sophisticated simulated games can be very expensive to manufacture and 
purchase. 
The object of the simulated tennis game of the present invention is to 
incorporate the best features of both nonelectrical games and electrical 
games and to improve upon the prior art by incorporating more elements of 
skill, strategy and chance into a microcomputer-controlled electronic 
gameboard. 
SUMMARY OF THE INVENTION 
This invention pertains to a microcomputer-controlled simulated tennis game 
using an electronic keyboard for player inputs and an electronic gameboard 
to display the results of a player's chosen input and his opponent's 
response thereto. The game incorporates elements of strategy, skill and 
chance. The keyed inputs of the opposing players are received by a 
microcomputer system which processes them according to a tennis simulation 
program and displays the results on the electronic gameboard. The 
electronic gameboard and the rules of the game are designated to conform 
as closely as possible to the actual game of tennis. This includes 
serving, volleying the ball, player movements and scoring. 
The electronic gameboard includes a scaled tennis court with outer 
boundaries, intermediate lines and net represented thereon to define the 
playing and serving areas. For games purposes, the scaled tennis court and 
its immediately surrounding area are divided into a grid having horizontal 
and vertical coordinates so that each square within the grid is uniquely 
identifiable to the players and to the microcomputer. The grid lines, 
while visible to the players, are not as visually evident as the court 
lines. Provision is made to illuminate squares on the grid to indicate 
ball and player positions, color coding being used to distinguish between 
the ball and the players. For this purpose, each square is a multiple 
color LED. The grid may include an area larger than that of the scale 
tennis court both to indicate normal player positions, especially at the 
base line, and to indicate ball shots which are out of bounds. 
The gameboard further includes a twelve-key keyboard for each player on 
which ten keys represent the ten digits and two code keys indicate whether 
the lateral (horizontal) or longitudinal (vertical) coordinate of a square 
on the grid is being selected by the keyed digits. By the use of both the 
code keys and the digit keys, a player can uniquely select any square on 
the grid both for his position and, when appropriate, the position of the 
ball. An error light appears above the keyboard to indicate invalid keyed 
inputs. 
The gameboard further includes an on-off switch, a reset switch, a switch 
to indicate which player is serving and a multiple position switch so 
players can select a novice, intermediate or advanced level of play. 
The gameboard also includes three indicator lights which tell a player 
whether he is to serve, volly or position himself on the gameboard by his 
next entry on the keyboard. 
Lastly, the gameboard includes an LED display to indicate scoring in 
points, games and sets. 
The electronic circuitry to support the gameboard operation includes a 
sixteen-line to four-line multiplexer (74154) which receives keyboard and 
reset inputs which are fed to an input/output control unit (such as an 
8255) and then to a microprocessor (such as an 8085) having a memory unit 
(such as an 8755). After inputs from each player are processed according 
to a tennis simulation program, appropriate outputs are fed to the 
gameboard through the input/output control unit to additional multiplexers 
(74154) to illuminate the squares on which the players are positioned and 
the position of the ball. When a point is scored, an LED display is 
illuminated on the score section of the gameboard. 
Using the electronic gameboard, two players may play a simulated game of 
tennis; or two teams may play a game of doubles. For purposes of 
description, only a game of singles will be described in terms of Player A 
and Player B. For doubles, one would simply substitute Team A and Team B 
and use the appropriate sidelines of the scaled tennis court. Initially, 
the gameboard is turned on and the reset button is pushed to set all 
displays to zero, to initiate the program and to turn off any illuminated 
squares on the tennis court grid. Each player then selects by switch or 
key whether he wishes to play a novice, intermediate or advanced game. 
This activates an odds selector in the microcomputer program which 
influences the probability of successful playing of a point on both serve 
and volley. The players then select which player is to serve by a visible 
toggle switch. Based on this information, the instruction indicator lights 
on each keyboard are illuminated, indicating to each player what data he 
should enter. At this point, each player then enters data on his keyboard. 
The server keys in the coordinates of the grid square to which he desires 
to serve within the appropriate service lines. At the same time, the 
player receiving the serve keys in the coordinates of the grid square on 
which he wishes to position himself to receive the serve. After a 
momentary delay, the keyed squares are illuminated and the program then 
determines the probability of the served ball hitting the desired square. 
All possibilities within tennis are considered by the program and its odds 
selector. For purposes of description, assuming the serve falls within the 
service area, the program then considers the probability of the receiving 
player returning the serve from his position. If that probability is below 
a threshold level for the level of play selected, the server scores a 
point. If it is above the threshold level, then the player instruction 
indicator lights come on to indicate to the receiving player that he 
should volley and to the server that he should position himself for the 
volley. Each player then keys in the coordinates of the appropriate grid 
squares, the receiving player indicating the square to which he wishes to 
return the ball and the other player indicating his desired position. The 
program will always position a player where he selects, but it will refer 
to an odds selector to determine where the ball lands and then whether the 
receiving player has a chance to successfully return the ball. Play 
continues until one player scores a point. The program always moves the 
ball and the player simultaneously to add suspense to the game. It also 
introduces a momentary delay between data inputs and its response for the 
same purpose. In the implementation of the gameboard, a multiple color LED 
is used for each square on the court grid to distinguish the player from 
the ball. Play is always under the control of the microcomputer which uses 
a program having weighted random probabilities to determine the outcome of 
each serve or volley. As mentioned, these probabilities may be varied by 
the user selection of the level of play. 
The invention also includes the digital logic necessary to implement the 
electronic-simulated tennis game.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
This invention pertains to an electronic simulated tennis game having an 
electronically operated gameboard on which the progress of the game is 
displayed, an input keyboard for players to enter their game moves and a 
programmed microcomputer system which controls the course of the game 
play. The microcomputer system includes a microprocessor, a memory unit 
and an input/output control unit. The figures illustrate the various 
physical components of the electronic game and include a flow chart for 
its program sequence. The figures are not intended to illustrate the 
product design. They simply show the invention diagrammatically. 
Referring now to the Drawings 
FIG. 1 illustrates the basic electronic simulated tennis gameboard of the 
present invention. The electronic gameboard 10 includes a rectangular 
representation of a tennis court area 12, proportioned similarly to a 
standard-sized court, having opposite baselines 14, 16 across each end, 
outer boundary lines 18, 20 along each side, inner sidelines 22, 24 spaced 
from each outer side, service lines 26, 28 at intermediate lateral 
positions between lines 22, 24 and parallel to and spaced from each end a 
net 30 across the center of court 12 and a centerline 32 lengthwise 
between the two service lines 26, 28. 
Court 12 is divided into a grid by horizontal and vertical lines, forming a 
plurality of generally square areas designated by numbered coordinates. 
For purposes of clarity of illustration, these numbered coordinates are 
shown from the viewpoint of one player, designated Player A. There are 
thiry-five squares along the outer sidelines 18, 20--numbered 1 to 35 
along the length of the court, with the net 30 being across row 18. There 
are also sixteen squares numbered 1 to 16 across the width along the 
baselines 14, 16. The full width of court 12 is used for a game of 
doubles, while only that portion between the inner sidelines 22, 24 is 
used for a game of singles. The numbers 1 through 17 are used to 
facilitate locating the positions on the opposite sides of the court. 
The players serve from behind the baselines 14, 16 and one side of the 
centerline 32 to hit the ball over the net 30 into the diagonally opposite 
service area bounded by the inner sidelines at 22, 24 and service lines 
26, 28 along the court on each side of the net. Locking at court 12 from 
the position of Player A, the area from the service line 26 to the 
baseline 14 is called the backcourt while the area between the service 
line 26 and the net 30 is called the forecourt. After the serve, all 
returned balls must land over the net 30 between the inner sidelines 22, 
24 and the baseline 16 for a singles games and between the outer sidelines 
18, 20 and the baseline 16 for a doubles game. 
On gameboard 10, the position of the ball is indicated by illuminating that 
square defined by its vertical and horizontal coordinates in the color 
green. The position of the player is indicated by illuminating his square 
with the color red. The means for illuminating the squares will be 
detailed hereinafter. 
Gameboard 10 also includes scoring displays which may be light-emitting 
diodes (LEDs). Display positions are provided for Points 40, 42 for each 
player or doubles Team A, B; Games 44, and Sets 46. Scoring is identical 
to that of the game of tennis. 
Gameboard 10 also includes an on-off switch 48 which is illuminated when 
the game is turned on, and a reset button 50 to reset all displays and 
circuits at the start of a game. In the electronic tennis game of the 
present invention, players can select whether they wish to play at the 
novice, intermediate or advanced level by pressing switches 52. The effect 
of this selection is to change the odds of successfully completing each 
stroke of the game. A switch 54 is provided to select which player or team 
will serve first. A switch 56 is provided to select whether the game will 
be singles or doubles. An error light 58 is provided to indicate an 
invalid switch or key input. 
Each player or team is provided with a keyboard 60 having twelve keys 
representing the digits zero to nine and two coordinate keys 62, one to 
indicate a lateral or horizontal coordinate and one to indicate a 
longitudinal or vertical coordinate of the tennis court grid 12. Using the 
coordinate keys 62 followed by the digit keys, the player can select any 
square on the grid of court 12 to position either himself or the ball, as 
required by the game. The use of the keyboard 60 will be explained 
hereinafter. 
Additionally, gameboard 10 is provided with instruction indicator lights 
which indicate to the player whether he is to Serve 64, Volley 66 or 
Position 68 himself on the court. These lights are illuminated by the 
microprocessor under program control to instruct the players as to which 
data should be keyed in. For example, if Player A is to serve, the 
microprocessor under program control will illuminate the serve light 64 at 
Player A's position and the position light 66 at Player B's position, 
indicating to Player A that he should key in the coordinates of the square 
on tennis court 12 to which he wishes to aim the serve and indicating to 
Player B that he should key in the coordinates of the square on tennis 
court 12 on which he wishes to position himself to receive the serve. 
Referring now to FIG. 2, the figure is a block diagram of the 
microprocessor controlled microcomputer system 80 which operates gameboard 
10 under program control. System 80 is shown in outline form omitting the 
common and well-known functions such as on-off, the power supply, the 
reset controls and the like. All inputs to system 80 are entered through 
the keyboard 60 and switches 52 (level of play) 54 (serve), and 56 
(singles or doubles). After initial start of the game with the on-off 
switch 48 in the on-position, the system 80 is reset by reset button 50, 
the level of play is set by switch 52, the choice of initial server is 
made by switch 54 and a singles or doubles game is selected by switch 56. 
The inputs from switches 52, 54 and 56 are processed by a sixteen-line to 
four-line multiplexer 82, such as a 74154, which also serves as the 
keyboard multiplexer. Data entered through the twelve keys of the keyboard 
is also processed through multiplexer 82. As illustrated in FIG. 3, ten 
lines of multiplexer 82 are utilized for inputs to System 80. From 
multiplexer 82, the input data is then processed by an input/output 
control unit 84, such as an 8085 (Intel) from which it is sent to 
microprocessor 86 for processing under program control. The program and 
volatile data are stored in a memory unit 88, such as an 8755 (Intel). The 
appropriate data, address and control lines 90 link the units of system 80 
together. After the input data is processed by system 80, its output 
returns through input/output control unit 84 to gameboard 10 in the form 
of illuminated grid squares or illuminated scoring displays. The data for 
illuminated grid square passes through multiplexers 92, 94 which control 
the row and column coordinates, respectively. Display outputs proceed 
through multiplexer 82 which is also the keyboard multiplexer. All 
multiplexers 82, 92 and 94 are 74154 multiplexers, the row multiplexers 92 
being six-line to 24-line multiplexers. 
Referring now to FIG. 3, the Keyboards 60, Switches 50, 52 and 54, and 
Instruction Indicator Lights 64, 66, 68 are shown in a keyboard 
arrangement slightly different from that of FIG. 1. Keyboard 60 has twelve 
keys, ten representing the digits from zero to nine and two code keys 62, 
which are used to indicate the lateral or longitudinal coordinates of 
squares on tennis court grid 12. To key in a location, the player first 
keys in the appropriate code key 62 followed by the number of its 
coordinate on that axis, then the other code key 62 followed by its 
coordinate on the other axis. For example, if Player A wished to serve to 
the grid square labeled 100 on FIG. 1, he would key-in the sequence LONG 
03 LAT 09. To position himself to receive the serve, Player B would key-in 
the sequence LONG 01 LAT 04, indicating grid square 102 of FIG. 1. The 
twelve keys of keyboard 60 are arranged in a three-by-four matrix which 
requires only three input lines to multiplexer 82. The Level Switch 52 
requires one line. Hence, each player position uses only four lines, for a 
total of eight. The Reset Switch 50 uses the ninth input line and the 
singles-doubles switch 56 uses the tenth line to multiplexer 82. In the 
arrangement of FIG. 3, the instruction indicator lights Serve 64, Volley 
66, Position 68, are shown in the keyboard layout. The operation of lights 
64, 66, 68 is under program control of the microprocessor 86. These lights 
instruct each player what inputs he should key in and their control also 
serves as a validity check on the inputs. An invalid switch or key entry 
will cause error indicator light 58 to be illuminated (FIG. 1). 
FIG. 4 is a partial schematic diagram of the circuit which is used to 
illuminate the tennis court grid 12 of gameboard 10. Sixteen grid squares 
are shown from columns 1 through 4 and rows 32 through 35 of FIG. 1. Each 
grid square 104 is a two color limit-emitting diode (LED) 106 known as 
MV5094 made by Monsanto. Using this LED 106, the player position is 
indicated by the color red and the ball position by the color green. Both 
colors can be illuminated on the same grid square 104 if the player and 
ball should meet on that square. In the course of the game three grid 
squares would normally be illuminated, one for the position of Player A, 
one for the position of Player B and one for the position of the ball. 
Gameboard 10 is basically a matrix having an LED 106 (MV5094) tied to each 
intersection of a row and a column. The MV5094 LED's 106 are tied cathode 
to anode and anode to cathode, and they are tied in parallel but backwards 
with respect to each other. If the current passes through one way LED 106 
will light up green; if it passes through the other way, LED 106 will 
light up red. LED's 106 are driven by tristate devices 108 such as the 
74125 which source about sixty milliamperes. Each LED 106 requires about 
twenty milliamperes. When the output of a tristate device 108 is in an 
active high condition, it sources sixty milliamperes. Tristate device 108 
can also sink any amount of current or in its third state it neither sinks 
nor sources current. Tristate device 108 usually is made in a package of 
four devices. One tristate device 108 is used to drive each row and each 
column of the grid matrix 12. The inputs to all tristate row drivers are 
tied together and the inputs to all tristate column drivers are tied 
together. The column tristate devices are inverted in relation to the row 
devices. For the grid square position of the ball to light up, the column 
tristate drivers sink current and the row tristate devices source current. 
For the position of the player to light up, this condition is reversed. 
Each tristate device 108 must source sixty milliamperes because the system 
is multiplexing among three positions, the ball, Player A and Player B for 
about one millisecond each. There will be no visible flicker because this 
time is long enough for tristate drivers 108 to be efficient. The time 
each LED 106 is on is long with respect to the switching time and hence 
there is no bleed-over, which would happen if one LED 106 is turned on 
before another is turned off. The output of each tristate device 108 goes 
to the row or column. The input of each tristate devices comes from the 
ball/player signal. The control or third lead tells the output to follow 
the input or to float (that is, neither sink nor source current). The 
control leads are tied to multiplexers 92, 94 (FIG. 2) which are connected 
to input/output control 84. Based on the keyed input and its program, 
microprocessor 86 feeds a code to input/output control 84 which holds the 
code in a latch and presents it to multiplexers 92, 94 which fan out and 
position the ball and players relative to the rows and columns. 
FIG. 5 shows the schematic drawing for the scoring displays 40, 42, 44 and 
46, instruction indicator lights 64, 66 and 68 and error lights 58. Codes 
for these displays and lights come from input/output control 84 to the 
keyboard multiplexer 82. An indicator drive 120 serves to drive LED's 122. 
Eight segment drivers 124 are used to illuminate scoring displays 40, 42, 
44 and 46. 
FIG. 5 A is a schematic of a typical segment driver 124. 
FIGS. 6 A, 6 B, and 6 C are a flow chart of the program used for electronic 
simulated tennis game 10. After start 48 and reset 50, the program reads 
the status of the level of play switches 52, singles-doubles switch 56 and 
initial serve switch 54. The system then reads the keyed input data from 
keyboard 60 and processes it, moving the players and the ball 
simultaneously after consulting an odds selector for the probability of 
the ball striking the intended grid square and for the probability of the 
player to return the ball from the position the player has chosen. The 
subroutines for the odds selectors take into account the angles of player 
positions and the level of play selected so that a real game of tennis may 
be simulated on gameboard 10. The flow chart of FIGS. 6A, 6B and 6C is 
self-explanatory with respect to scoring upon completion of a serve or 
volley and with respect to the player instruction indicator lights 64, 66 
68. 
For a game of doubles, appropriate modifications in the gameboard circuit 
would be made to illuminate two player positions on each side of the net 
and appropriate program modifications would be made in the program, 
especially the odds selector, to provide for volleying by four players 
rather than two. 
It may be thus seen that the present invention provides a novel simulated 
tennis game using a microcomputer system to operate a realistic electronic 
gameboard. While one embodiment has been illustrated and described, it is 
apparent that many variations may be made in the particular form and 
construction without departing from the scope of the invention as set 
forth in the appended claims.