GB2075229A - >Random number selection - Google Patents

Abstract

Electrical circuit means for selecting a number from a predetermined range, the selection process being to a degree random but incorporating a bias, includes a range counter which counts repetitively over a pre-set range. A number is selected by interrupting the range counter at a random point in time and a desired degree of bias can be introduced by causing the range counter to dwell on certain numbers.

Description

SPECIFICATION Electrical circuit means This invention relates to electrical means for providing random numbers and has for its object the provision of relatively inexpensive electrical circuit means capable of selecting a number from a predetermined range, the selection process being to a degree random but incorporating a bias, in the form of a predetermined bias value, tending to favour the selection of certain numbers.

To this end, the present invention consists in electrical circuit means comprising means for entering selected range and bias numbers into range and bias stores respectively; a range counter adapted when activated to count repetitively between the value of the range store and a fixed value; means for delaying the count of the range counter at intervals dependent upon the value of the bias store; means for interrupting the range counter and means for displaying the content of the range counter upon interruption.

Advantageously, the delaying means comprises a loop counter arranged to count down from the value of the bias store in synchronism with the range counter, the delay means serving to delay the count of the range counter by a fixed delay whenever the loop counter assumes a pre-set value.

Preferably, said means for activating the range counter and said interrupting means are controlled by a single trigger device, a first pressure on the trigger thereby serving to activate the range counter and a second pressure serving to interrupt the count.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a flow diagram showing the manner in which range and bias numbers are entered in electrical circuit means according to the invention and, Figure 2 is a flow diagram illustrating the selection process of electrical circuit means according to the invention.

It is intended that electrical circuit means according to this invention will be micro-processor based and will incorporate a two digit display, two buttons A and B and a trigger which recognises first and second trigger pressures. For the sake of clarity, the term "pressing the trigger" will be used hereinafter to denote the application of light, first pressure to the trigger, the term "squeezing the trigger" being reserved for the application of further pressure to the trigger.

Briefly, the two buttons A and B are used to enter into the device a range number and a bias number.

When the trigger is pressed, the device will begin to count down from the range number and will continue counting until the trigger is squeezed. The number held in the counter at the instant of squeezing the trigger is then displayed as the result of the selection process. Since the delay between pressing and squeezing the trigger is random and will generally encompass many cycles of the range counter, the number selected would - if the counting were steady - be a random number. However, the device further incorporates a delay routine causing the range counter to dwell on certain numbers accord ing to the value of the bias number entered. It will be appreciated that those numbers at which the counting process is temporarily halted will be more likely to be selected.

The operation of the device will now be described in greater detail. The flow diagram of Figure 1 illustrates the manner in which a two digit range number is entered into the device using button B.

Button A-is used in a completely analogous manner to enterthe bias number into the device and the following description is generally applicable to both entry routines.

At the start of the range entry routine, a flag RD is set to zero; this flag is used to enable the routine to handle first the left hand digit of the range number and then the right hand digit. Button A is then interrogated to checkwhetherthe bias number entry routine is being used and, if it is not button B is interrogated. Assuming for the moment that the button has not been pressed, a check is then made to see whether the trigger has been pressed and, if it has, the device will switch to the select routine described more fully hereinafter. Provided the trigger is not being pressed, the device will examine the state of the flag RD and will increment either the left hand or right hand digit of the range number. As will be seen, provision is made for resetting the digit to nought every tenth increment.Initially, since the flag RD has been set to nought the right hand digit of the range will be incremented and provided the buttons or trigger are not pressed, this sub-routine will be repeated continuously. The user is able to select a particular digit by pressing button B when that digit is displayed,the device will then display the range and examine the flag RD to decide whether both digits have been selected. If RD is zero, it will be set to one and the selection process will be repeated on the left hand digit. At the end of the left hand digit selection process flag RD will be one and the device will move to an idle routine.

In this way, one or two digit numbers can be entered into range and bias stores. Referring now to Figure 2, the selection routine starts by setting the value of a loop counter to the content of the bias store and the value of a range counter to the content of the range store. Assuming then that the trigger is pressed but not squeezed, the range counter will be decremented and the state of the loop counter examined. If the loop counter is not at zero, it will also be decremented and the routine will repeat with the values of the loop and range counters being reset if the range counter is at zero. When the loop counter reaches zero a delay is introduced before the routine repeats with the loop counter being reset. In this way the device counts down repetitively from the range number delaying by a predetermined amount at regular intervals dependent upon the bias number.When the trigger is squeezed the routine first examines whether sufficient time has elapsed since pressing of the trigger to enable proper selection; the display indicator E being generated if sufficient time has not elapsed. Provided the trigger is not squeezed too rapidly after the initial pressure, the content of the range counter will be displayed as the selected number.

This invention has been described by way of example only and it will be appreciated that numerous modifications can be made without departing from the scope of the invention. Thus for example the range counter could be organised to count up from zero to the range number or, indeed, could count between the range number and any fixed value. Other methods of entering into the device a range number and a bias number could be employed, for example a keyboard, although the described arrangement has the merit of keeping hardware costs to a minimum.

Claims (4)

1. Electrical circuit means comprising means for entering selected range and bias numbers into range and bias stores respectively; a range counter adapted when activated to count repetitively between the value of the range store and a fixed value; means for delaying the count of the range counter at intervals dependent upon the value of the bias store; means for interrupting the range counter and means for displaying the content of the range counter upon interruption.

2. Electrical circuit means according Claim 1, wherein the delaying means comprises a loop counter arranged to count down from the value of the bias store in synchronism with the range counter, the delay means serving to delay the count of the range counter by a fixed delay whenever the loop counter assumes a pre-set value.

3. Electrical circuit means according to Claim 1 or Claim 2, wherein said means for activating the range counter and said interrupting means are controlled by a single trigger device, a first pressure on the trigger thereby serving to activate the range counter and a second pressure serving to interrupt the count.

4. Electrical circuit means substantially as hereinbefore described with reference to and as shown in the accompanying drawings.