Electronic novelty device and method of using same

A novelty device and method of using it, include at least three lamp sockets, and at least three lamps, which are each capable of producing at least three different colored lights, such as red, green and orange light. The lamps are housed in opaque translucent enclosures or housings, to prevent their colors from being known until they are illuminated by a set of at least three corresponding manually operable switches. When the switches are actuated, the lamps each emit a different colored light to provide the appearance that each lamp is of a different color. A control device in the form of a microprocessor secretly enables the user to cause the lamps to emit the desired color even after the lamps are removed from the sockets, mixed, and then re-inserted.

TECHINICAL FIELD 
The present invention relates in general to an electronic novelty device, 
and a method of using it. The invention more particularly relates to such 
a novelty device, which is also capable of functioning as a magic trick. 
BACKGROUND ART 
Novelty devices have been employed for many years for the purpose of 
entertaining people. Such novelty devices have included loops and rings, 
which are linked together in such a manner that the operator can quickly 
and easily disconnect them. However, the spectator, when asked to perform 
such a feat, is unable to duplicate it. 
While such devices are amusing, they are not always very challenging to 
more sophisticated or educated persons. In this regard, adults may not 
find such a novelty item or puzzle to be very amusing or challenging. Such 
an adult may well be able to quickly and easily determine the secret for 
solving the puzzle by a mere visual inspection in a relatively short 
period of time. Thus, it would be highly desirable to have a novelty 
device which is very entertaining, and not subject to learning the secret 
to solving the puzzle in a ready manner, even by sophisticated adults who 
may have technical education or experience. 
Such novelty devices have included magical apparatus used by magicians in 
performing magic tricks on the stage. For example, there have been 
remotely controlled devices employing radio frequency signals to enable 
the magician performer to activate secretly a device at a distance. 
However, such an apparatus is not at all susceptible to examination by the 
audience, without revealing the secret of its operation. certainly, an 
engineer or scientist could readily inspect such an apparatus and 
determine exactly how it operates. The radio transmitter or receiver would 
be apparent by visual inspection, and the thought process of the more 
sophisticated spectator could readily analyze the device to determine the 
nature of its operation. Thus, it would be highly desirable to have a 
novelty device which is constructed and arranged such that its operation 
is not readily susceptible to detection by an audience, including highly 
trained and skilled persons who might otherwise be able to analyze and 
determine the nature of the operation of the device. 
Many magic tricks have been operable only in the hands of a skilled 
magician, which raises the natural suspicion that the magician is 
controlling the trick in some way unknown to the audience. It would be 
highly desirable to have a novelty device which exhibits its baffling and 
entertaining properties in the hands of the spectators, with the magician 
apparently taking no part in the process. 
Some magic tricks require the magician to perform a covert operation to 
enable the trick to function in a desired manner, and then to perform 
another covert operation to disable the part of the trick that he or she 
desires to conceal from discovery by the audience. In this manner, the 
device can subsequently be examined by the audience, without detecting the 
secret of the baffling mode of operation. It would be preferable to have a 
novelty device that functions identically, whether in the operator's hands 
or in the spectator's hands, with no change of operating mode, and yet 
enable the operator to cause the device to operate in an unexpected and 
unusual manner, which cannot be duplicated by the spectators. 
Magic tricks made for professional magicians often require special skill, 
such as sleight-of-hand, to operate. It would be desirable to have a trick 
device, which is easily operable by people of ordinary skill, including 
children. Ideally, such a device should appeal to all age groups. 
In the hands of children, it would be very desirable if the device requires 
mental dexterity to operate, so that its secret cannot be discovered 
accidentally, or by chance. Parents prefer to give their children toys and 
games that require some mental dexterity to operate, to stimulate 
thinking. Thus, it is highly desirable to have a novelty device, which not 
only may be employed as a magic trick, but also may be used as an 
educational or otherwise amusing and entertaining toy or puzzle. Such a 
device should require some skill to operate, but the required skill should 
require a general mental acuity only. No specialized or difficult skill 
such as sleight-of-hand performed by skilled magicians, should be 
required. Thus, such a device could be used by a wide range of ages of 
operators. 
It would be very desirable if such a device were portable and could be 
manufactured at relatively low cost. With suitable packaging, such a 
device should be marketable as a unique and somewhat expensive desk 
accessory or a coffee table conversation piece. 
DISCLOSURE OF INVENTION 
Therefore, the principal object of the present invention is to provide a 
new and improved novelty device and method of using it, wherein a 
technically unsophisticated operator can operate the device in a baffling 
and entertaining manner, without permitting a technically experienced 
person to discover how the novelty device functions. 
A novelty device and method of using it, include at least three lamp 
sockets, and at least three lamps, which are each capable of producing at 
least three different colored lights, such as red, green and orange light. 
The lamps are housed in opaque translucent enclosures or housings, to 
prevent their colors from being known until they are illuminated by a set 
of at least three corresponding manually operable switches. When the 
switches are actuated, the lamps each emit a different colored light to 
provide the appearance that each lamp is of a different color. A control 
device in the form of a microprocessor secretly enables the user to cause 
the lamps to emit the desired color even after the lamps are removed from 
the sockets, mixed, and then re-inserted.

BEST MODE FOR CARRYING OUT THE INVENTION 
Referring now to FIGS. 1, 2 and 3, there is illustrated a novelty device 
10, which is constructed in accordance with the present invention. 
Referring to FIG. 1, device 20 generally comprises a playing surface 15 of 
a housing 16 containing three identical receptacles or electrical sockets 
1, 2 and 3, and three identical manually operable switches 4, 5 and 6 
disposed within the housing 16 below a set of three holes or openings 31, 
32 and 33, respectively. Three like lamps 7, 8 and 9 are enclosed in 
opaque translucent housings, such that the color of each unpowered lamp 
cannot be observed. The lamps 7-9 can be inserted into respective 
receptacles 1, 2 and 3 in any order. Three like identical pushbutton tops 
10, 11 and 12 are colored red, green and orange, respectively. The 
pushbuttons are designed to fit through the respective holes and extend 
into engagement with the switches 4, 5 and 6, and when depressed manually 
by the user, they actuate the respective switches. 
Each of the lamps 7-9 is capable, when illuminated, of providing three 
different colors, red, green and orange. The pushbuttons 10-12 each bear a 
different color, namely red, green and orange, respectively. However, the 
actual color of any lamp is not discernible until it is plugged into one 
of the receptacles or sockets 1-3 and its corresponding pushbutton switch 
is pressed to illuminate its lamp. In FIG. 1, the switch 4 controls the 
lamp in receptacle 1, the switch 5 control the lamp in the receptacle 2, 
and the switch 6 controls the lamp in the receptacle 3. In this regard, 
each one of the switches controls the corresponding lamp receptacles 1-3 
disposed adjacent thereto. 
In operation, a spectator is invited to mix up the lamps 7-9, and then to 
insert them individually into any desired ones of the receptacles 1-3 in 
any desired order (FIG. 2). Although FIG. 2 shows lamp 7 in receptacle 1, 
lamp 8 in receptacle 2, and lamp 9 in receptacle 3, the lamps could be 
placed in any of six possible combinations. The spectator is lead to 
believe that each one of the lamps is different in that each one emits a 
different colored light when illuminated. However, in reality, the three 
lamps 7-9 are similar to one another and each one is capable of emitting 
all three colors of light, as hereinafter described in greater detail, 
even though the opaque housings prevent the spectator from knowing in 
advance which color will be emitted prior to illumination. 
Once the three lamps 7-9 are placed into receptacles 1-3, the operator 
attempts to place the pushbuttons 10-12 through the holes 31-33 into 
engagement with the three switches 4-6 so that each colored pushbutton is 
placed opposite a lamp emitting its corresponding colored light. Once 
inserted, the operator presses the pushbuttons 10-12, actuating the 
switches underneath the pushbuttons, and to the amazement of the 
spectators, achieves a match of pushbutton and lamp colors. Furthermore, 
the operator can accomplish this matching every time the above sequence of 
events is repeated. 
Many variations of device operation are possible. For example, the operator 
can employ more than one spectator, asking spectator No. 1 to insert the 
lamps in any desired order, and then asking spectator No. 2 to correctly 
match the pushbuttons to the lamps. Spectator No. 2 will probably not be 
able to accomplish the match. However, the operator can secretly cause the 
match to be made each time, without the spectators knowing. In a group of 
spectators, one of the spectators achieve a perfect match every time under 
the secret control of the operator (magician), while others do not, is 
quite mysterious and vexing, especially when the operator has no apparent 
influence over the placement of the pushbutton by the spectator, who is 
freely inserting the pushbuttons into any one of the holes in the housing. 
Another variation is that the operator can place the pushbuttons over the 
switches first, and then have the spectator plug in the lamps in any 
order, and still achieve a perfect match. 
The device operates in the manner described due to two special properties 
not known to the spectators and only known to the operator magician. 
Firstly, each lamp is capable of illuminating in any one of three colors; 
namely, red, green or orange. Secondly, there is a microprocessor 100 
(FIG. 6) inside the housing and is responsive to the three switches 4-6. 
The microprocessor 100 can detect if the lamps are plugged in or not. The 
microprocessor 100 is capable of powering each lamp in three different 
modes of operation to cause a lamp to turn on with the red, green or 
orange color. 
For description purposes, the following terminology is adopted. The 
placement of lamps and pushbuttons and the verification of pushbutton-lamp 
colors is referred to as a "round." A round constitutes three phases, the 
"lamp placement" phase, the "pushbutton placement" phase, and the "test" 
phase. 
The first phase in a round is the lamp placement phase, during which the 
three lamps are removed, scrambled, and handed to the spectator to 
re-insert them in any order. Once the lamps are inserted, the lamp 
placement phase is over and the pushbutton placement phase begins. In the 
pushbutton placement phase, the operator places the pushbutton onto the 
switches. Then the test phase commences, during which the operator presses 
the pushbuttons to test whether or not the pushbutton colors match the 
lamp colors. The act of removing the three lamps terminates the check 
phase and initiates the next lamp placement phase. 
During the test phase of a round, as the operator or spectator presses the 
pushbuttons to illuminate the lamps and check the correspondence of 
pushbutton colors to lamp colors, the operator watches carefully to note 
which of the switches is released last. In this regard, the colors red, 
green and orange are associated by the operator with the corresponding 
holes 31, 32 and 33, respectively. Whichever one of the switches 
corresponding to its hole 31, 32 or 33 is released last prior to the 
removal of all of the lamps, determines the color of light of the first 
switch actuated during the next round when all of the lamps are reinserted 
in any order, under the control of the microprocessor 100. 
For example, if the switch 4 (FIG. 1) is released last, then the operator 
remembers the color red as being associated with the left hand hole 31 in 
the row of holes. If the switch 5 is released last, then the operator 
remembers the color green. If switch 6 is released last, then the operator 
remembers the color orange. The secret to the device operation is that the 
color that is ascertained by watching the order of switch releases will be 
the "starting color" for the next round, where the "starting color" is the 
color of light emitted by a lamp corresponding to the first switch pressed 
in the test phase of the next round. 
Suppose the last pushbutton released as the switch/lamp colors are tested 
is the middle switch 5 in FIG. 1. This corresponds to the starting color 
of green. After the lamps are removed and replaced, a new pushbutton 
placement phase commences during which the operator places the pushbuttons 
over the switches. Then a test phase commences to check the pushbutton and 
lamp colors. The first pushbutton pressed will illuminate the 
corresponding lamp green, since green is the starting color that was 
ascertained from the previous round. This is true regardless of the 
placement of the green pushbutton. In other words, the operator can place 
the green pushbutton over any of the three switches 1, 2 or 3, and as long 
as the first pushbutton pressed during the test phase is the green 
pushbutton, the associated lamp will be powered by the microprocessor 100 
in the green state, since the microprocessor is so programmed. 
The operator then secretly makes use of the knowledge that the pushbutton 
switches should be tested in a predetermined sequence, for example 
according to Table I. 
TABLE I 
______________________________________ 
Starting color Second color 
Third color 
______________________________________ 
red green orange 
green orange red 
orange red green 
______________________________________ 
For the present example, with green as the starting color, the second 
switch pressed illuminates its lamp as orange, and the third switch 
pressed illuminates its lamp as red. 
As another example, suppose the last switch released is the left switch 4, 
establishing red as the starting color. The lamps are removed, scrambled 
and re-inserted. The operator places the pushbuttons anywhere and presses 
first the red pushbutton, then the green pushbutton, and last the orange 
pushbutton. Because the colors were pressed in the correct order, the 
pushbutton and lamp colors match, regardless of where the pushbuttons were 
actually placed (which ones of the holes 31-33). 
It is possible to vary the technique used to press the pushbuttons in the 
correct order. For example, if red is the starting color, the operator can 
first place the red pushbutton and press the underlying switch before 
placing the other two pushbuttons. Then the green pushbutton can be placed 
and actuated, and then the orange. This technique is very useful when the 
operator wishes to create the illusion that the operator is somehow 
magically controlling the spectator to cause him or her to place the 
pushbuttons in the proper holes to match the pushbuttons with the lamps. 
As long as the operator hands the pushbuttons to the spectator in the 
right order as determined by the microprocessor 100, and the spectator 
inserts and presses each pushbutton before being handed the next 
pushbutton, the operator can insure that the spectator presses the 
pushbuttons in the correct order, thus successfully matching the 
pushbutton and lamp colors. Alternatively, the operator can cause a 
different spectator to fail to correctly match the colors by handing the 
pushbuttons in an incorrect order. Therefore the operator has complete 
control over who matches and who does not match the colors. 
As another example, suppose the starting color is orange, because the last 
switch released before the lamps were unplugged, was switch 6. The 
operator places the pushbuttons orange, red, green. Then the lamps are 
removed, scrambled and replaced. The operator then presses the orange 
pushbutton, then the red pushbutton, and then the green pushbutton, thus 
illuminating the correct colors. Actually, the pushbuttons could be placed 
in any sequence of the holes 31-33, as long as the operator presses first 
the orange, then the red, and then the green pushbuttons in sequence. 
An important aspect of the device is that once the pushbuttons have been 
pressed in the correct order as described above, the switches subsequently 
may be pressed in any order, individually or simultaneously, any number of 
times, and the pushbutton-lamp color relationships that were established 
for the first three presses remain in effect. This ability convinces the 
spectator that each lamp emits a different colored light, and thus each 
lamp is a different color. 
Also, during the test phase, once a pushbutton is pressed to determine the 
color of its lamp, the same pushbutton may be pressed repeatedly before 
pressing another pushbutton, and the lamp will continue to illuminate with 
its assigned color. It therefore appears that the pushbuttons are indeed 
"hard-wired" to their corresponding lamps. 
Addressing now the first special property, the like multicolored lamps 7-9 
will now be considered. FIG. 4 shows the construction of one of the lamps, 
the other two lamps not being described further as they are similar. A 
plug 40 is a conventional two terminal plug, and is in the form of a 
coaxial power jack. A light emitting diode (LED) 41 is connected 
electrically to the two terminals of plug 40. A translucent shroud or 
housing 42 fits over the assembly and is opaque to conceal the diodes from 
view, and yet permit the light to illuminate the housing 41, when either 
one or both of the diodes are energized. 
FIG. 5 illustrates the LED 41 in schematic form. The LED package actually 
contains two LED devices, connected electrically back-to-back in parallel. 
One of the LED devices is red (51), and the other is green (52). Applying 
a positive voltage to A with respect to B causes current to flow through 
diode 51 but not through diode 52, resulting in the red LED 51 turning on. 
Conversely, applying a positive voltage to B with respect to A causes 
current to flow through diode 52 but not through diode 51, resulting in 
the green LED 51 being activated. Also, applying an AC voltage across A 
and B, which rapidly reverses the polarity of the applied voltage, causes 
both LED 51 and LED 52 alternately to turn on emit orange colored light. 
If the frequency of the applied AC voltage is greater than about 40 Hz, no 
flicker is perceived, and the LED 41 appears to be a single-color orange 
lamp. If the duty cycle of the applied AC voltage is 50%, the resulting 
color is a third color, which is a mixture of the two LED colors, and in 
the preferred form of the invention in the color orange. 
The LED 41 is conventional, and is marketed by QT Optoelectronics, 610 
North Mary Ave, Sunnyvale, Calif. 94086, as model MV5491A bicolor solid 
state lamp, which includes two light emitting diodes with wavelengths of 
about 568 and about 650 nanometers, thereby providing the colors green and 
red, and causing the mixed color to be of the average wavelength of about 
609 nanometers, which is the color orange. 
Addressing the second special property, the microprocessor 100 and program 
therein, FIG. 6 is a schematic diagram for the device electronics. FIG. 7 
is an oscilloscope graph of an LED drive signal used to determine whether 
or not a lamp is plugged in, and FIG. 8 is a flowchart for the 
microprocessor background program. FIG. 9 is a flowchart for the 
microprocessor interrupt routine. 
Turning now to FIG. 6, there is shown a schematic diagram of the control 
circuit 150 for the device 20. The microprocessor 100 is controlled by a 
computer program shown in FIGS. 8 and 9. Microprocessor 100 is a Zilog 
Z86E04, a single chip processor with an Electrically Programmable ROM 
(EPROM), or a Z86C04, which uses a masked ROM. This processor, which is a 
member of the Zilog Z8 family, is described in the Zilog data book DC 
8318-01, entitled Discrete Z8 Microcontrollers, dated Q2/94, incorporated 
herein by reference as if fully set forth herein. 
A crystal 101 establishes a precise internal clock frequency for the 
microprocessor 100. A pair of capacitors 102 and 103 provide the proper 
loading for crystal 101. One contact of lamp receptacle 1 is connected to 
microprocessor port pin P25 through current limiting resistor 104, and the 
other contact of lamp receptacle 1 is connected to microprocessor port P24 
through current limiting resistor 105. One contact of lamp receptacle 2 is 
connected to microprocessor port pin P23 through current limiting resistor 
106, and the other contact of lamp receptacle 2 is connected to 
microprocessor port P22 through current limiting resistor 107. One contact 
of lamp receptacle 3 is connected to microprocessor port pin P21 through 
current limiting resistor 108, and the other contact of lamp receptacle 3 
is connected to microprocessor port P20 through current limiting resistor 
109. 
Each of the port pins can be programmed to be an input or output pin by the 
computer program 100. Load resistors 110, 111, 112 are used to complete 
the circuit to ground when the lamps are unplugged, allowing the 
microprocessor 100 to determine if a lamp is inserted or removed from the 
receptacle. The lamp assemblies 7, 8 and 9 are shown for reference as 
plugging into receptacles 1, 2 and 3. 
Momentary pushbutton switch 4 is connected to microprocessor port P31, and 
also to a pull-up resistor 117 which insures that the state of the P31 pin 
is high when the pushbutton is not pressed, and also to diode 113 which is 
used to form a logical "NOR" signal at microprocessor port pin P27. This 
"NOR" signal, formed by the three diodes 113, 114, 115 and resistor 116, 
goes low when any of the three pushbuttons is pressed. The "NOR" signal is 
used to command the microprocessor 100 to exit a low power "sleep" mode 
whenever a pushbutton is pressed. Momentary pushbutton switch 5 is 
connected to microprocessor port P32, and also to pull-up resistor 118 and 
diode 114. Momentary pushbutton switch 6 is connected to microprocessor 
port P33, and also to pull-up resistor 119 and diode 115. 
The device is powered by a battery 120, which is in the form of four 
standard "AA" penlight cells. By making use of the microprocessor's 
low-power sleep mode, the device can automatically turn itself off after 
about 10 minutes of inactivity (no pushbuttons pressed), dropping the 
quiescent current consumption to about 50 microamps, and making a power 
switch unnecessary. The lack of a power switch adds to the impression that 
there is nothing in the device except switches, lamps and a battery. 
The purpose for the load resistors 110, 111 and 112 will now be described. 
The microprocessor 100 must have some means for detecting when all lamps 
are unplugged, so that it knows when to begin a new round. Every 65 
milliseconds, the microprocessor sends a very brief test pulse to each 
receptacle to check for the presence of a lamp. Although all three 
receptacles are tested at once, for clarity only the port connected to 
receptacle 1 will be described. 
P25 and P24 are normally set to function as output pins, which drive high 
or low to activate the lamp 7. When it is time to test for the presence of 
a lamp, the microprocessor 100 first saves the state of the p24 and p25 
output pins. Then it re-programs P25 to function as an input pin, and 
drives P24 high. If no lamp is plugged in, resistor 110 pulls the voltage 
of the unconnected input pin P25 to ground and the microprocessor program 
reads the state of P25 as "0." 
If a lamp is plugged in, a circuit is completed from P24 (at approx. 6 
volts) through the diode 130 and load resistor 110. This causes the 
voltage seen by P25 to be a diode drop below 6 volts minus voltage drops 
due to resistors 105 and 110, which is approximately 4.2 volts, which 
represents a logic 1 to the input pin P25. Thus P25 reads a "0" if the 
lamp is unplugged and "1" if it is plugged in. 
FIG. 7 illustrates a typical waveform for P25 during the time that the 
presence of a lamp is checked. The top trace corresponds to a lamp that is 
plugged in, and the bottom trace corresponds to an unplugged lamp. Point 
"A" indicates the moment that P24 drives high, "B" indicates the moment 
that P25 becomes an input port, "C" indicates the moment that the 
processor tests the state of P25, and "D" indicates the moment that the 
pins P24 and P25 are returned to their normal (output) states. It can be 
seen that a plugged-in lamp presents a logic HI at time C in the top 
trace, and an unplugged lamp presents a logic LO at time C in the bottom 
trace. 
The sequence of program steps to test for the lamps is shown in Appendix A, 
which is a complete listing of the program that executes in microprocessor 
100. The state of port 2 is saved in statement 196, the pins are 
reprogrammed as a mixture of inputs and outputs in statements 197-198, the 
state of the input pins are tested in statement 199, and the ports are 
restored as outputs in statements 200-201. The time interval that each 
lamp is illuminated is very small, and the current through the LED is also 
very small, so any lamps that are plugged in are not observable as "on" 
during the time that the microprocessor checks for the presence of 
plugged-in lamps. 
The program logic flow is diagrammed in FIG. 8 which is a flowchart for the 
main program, and FIG. 9 which is a flowchart for the interrupt routine. 
Turning now to FIG. 8, there is shown a flowchart for the program in 
Appendix A. The program initializes at 200, when the power is turned on by 
plugging in the batteries. At 201 the variable LASTBUT which holds a 
number indicating the last pushbutton released is set to 1. The values of 
LASTBUT are red=1 (corresponding to switch 4 in FIG. 1), green=2 (switch 5 
in FIG. 1) and orange=3 (switch 6 in FIG. 1). At 202 the variable 
NEXTCOLOR is set to the value of LASTBUT. This establishes red as the 
starting color for the round, but only for the first round after power is 
applied. The possible values of NEXTCOLOR are the same as for LASTBUT, 
namely red=1, green=2, orange=3. 
The program then proceeds to 203, where a check is made to see if any 
pushbuttons are depressed. If none of the pushbuttons are depressed the 
program proceeds to 209, where a test is made to ascertain if all lamps 
are unplugged. This test is accomplished by examining the variable ALLOUT, 
which is updated in the interrupt service routine. If all of the lamps are 
not unplugged the program loops back to 203, where the pushbuttons are 
again tested. 
If any pushbuttons are down at 203, the program branches to 204, where the 
variable LASTBUT is updated to reflect the pushbutton or pushbuttons 
pressed. When all pushbuttons are up, the update at 204 does not occur, 
and thus LASTBUT holds the state of the last pushbutton that was down 
before all pushbuttons were up, i.e. the last pushbutton released. 
A check is then made at 205 to determine if the pushbutton being pressed 
has already been assigned a lamp color. If it has, the program proceeds to 
209. If the pushbutton has not been assigned a lamp color (it is being 
pressed for the first time in a round), it is assigned the lamp color held 
in the variable NEXTCOLOR. The variable NEXTCOLOR is then updated (in the 
subroutine UPDATE.sub.-- NEXTCOLOR, Appendix A lines 160-170) by 
incrementing the value 1 to 2, the value 2 to 3, or the value 3 to 1. 
If all of the lamps are unplugged at 209, the program branches to 202, 
where the value of LASTBUT is copied into the variable NEXTCOLOR. This is 
how the last pushbutton pressed becomes the beginning color for the next 
round. 
Turning now to FIG. 9, there is shown a flowchart for an interrupt service 
routine. The microprocessor 100 contains a timer circuit that is 
initialized to interrupt the main program every 5.12 milliseconds 
(Appendix A, lines 85-99). At 300 the interrupt service routine is 
entered. At 301 the lamp receptacles are tested for the presence of lamps, 
and the variable ALLOUT is set to 1 if all lamps are unplugged, and to 0 
otherwise. Then the pushbuttons are checked at 302 to see if any are 
depressed, and the corresponding lamp is turned on for each depressed 
pushbutton at 303. If a pushbutton has not yet been assigned a color, its 
lamp is not activated. The interrupt service routine exits at 304, 
returning the microprocessor to its background program (FIG. 8). 
The variable TOGMASK is complemented every time the interrupt service 
routine is activated (every 5.12 milliseconds), and this value is used to 
drive the orange colored lamp. This drives the lamp with the 50% duty 
cycle signal required to turn on both LEDS to produce the mixed third 
color (orange). 
Appendix A is a fully commented listing of the microprocessor program. 
While particular embodiments of the present invention have been disclosed, 
it is to be understood that various different modifications are possible 
and are contemplated within the true spirit and scope of the appended 
claims. There is no intention, therefore, of limitations to the exact 
abstract or disclosure herein presented.