GB2104259A - Calculator apparatus - Google Patents

Abstract

A calculator is described having a function keyboard (14), a numeric keyboard (15) and a display 13. When carrying out complex calculations the display 13 indicates at least part of the keyboard 14 to thus indicate the keys which will be used during a particularly selected calculation and/or which key or keys is/are to be pressed next in order to continue the calculation and/or which keys have already been pressed to avoid inserting the same information more than once. A further aspect relates to a portable calculator having a battery power supply in which the more complex calculations are carried out on a high speed relatively high power processing unit which is only switched on during calculations so as to save battery power, the other more simple operations being carried out by a low power consuming processing unit. <IMAGE>

Description

SPECIFICATION Calculator apparatus The present invention relates to an improvement in calculator apparatus. Although calculators are widely used from the simple hand-held battery operated calculators through to more complicated desk top calculators, there are a number of problems.

Firstly, with the more complex type of calculator, in which a complex keyboard is incorporated, it can be difficult for a person to determine either the order of entry of information through the keyboard, or what keys are required during the calculation.

Further with calculators such as hand-held programmable type calculators can take a considerable time for complex calculations to be carried out by the machine. For example if the calculation includes an iteritive calculation (that is a calculation which is carried out by means of successive approximations) the time to produce an answer can be great. In a particular instance, in a programmable portable calculator including a programme for use by bond traders (fixed interest security dealers) in which complicated iteritive calculations relating to compound interest, exchange rates sinking funds and the like are used, it can take up to approximately 45 seconds for the calculator to carry out the calculation and produce the result.

According to one broad aspect the present invention relates to calculator apparatus comprising a portable calculator having a power supply, a relatively high-speed, relatively high-power processing unit (for example a microprocessor utilising a NMOS or HMOS chip) a relatively lower speed, relatively lower power processing unit (eg a microprocessor utilising a CMOS chip), the arrangement being such that all or the more complex calculations are carried out by the high-speed processing unit which is only powered during these calculations.In this way battery power which would otherwise be drained very quickly by the high-speed processor if it was to remain switched on all the time is conserved since the simplerfunctions such as driving the display, storing the information in registers and the like is controlled by the low-speed processing unit, only the more complex "number crunching" operations being carried out bythe high-speed processing unit.

The use of this principle enables one to produce a battery operated portable calculator which will carry out extremely complex calculations and at the same time give a resonable length of battery life.

In another arrangement of the invention there is provided a calculator apparatus including a keyboard, and a display, the display including an indication of the keyboard and, during use, the indication of the keyboard indicates (a) the keys which will be used during a particular selected calculation and/or (b) which key or keys is/are to be pressed next in order to complete the calculation and/or (c) which keys have already been pressed to avoid inserting the same information more than once. This is particularly useful with a calculator with a complex keyboard with which the user is not entirely familiar as it helps to guide the user through the calculation.If the calculator is capable of carrying out several types of predetermined calculations which do not reqire all of the keys to be used, then the display may indicate which keys are to be used during a particular calculation in question.

A particular type of display will be described hereafter.

A preferred embodiment of the invention will now be described by way of example only with reference to the accompanying drawings which show a calculator apparatus which has been primarily designed for use in carrying out various calculations relating to bond trading. However, similar principles would be applicable to other calculators capable of carrying out advanced mathematical computations, such as might be used in science, mathematics, astronomy, hire purchase, mortgage and other loan calculations, and the like.

In the drawings: Figure 1 is a front perspective view of the calculator apparatus according to the invention, Figure 2 is a front diagrammatic view of the display and one of the keyboards of the calculator apparatus of Figure 1 with all of the possible characters on the display shown.

Figure 3 is a front diagrammatic view of the other keyboard of the calculator apparatus of Figure 1, Figure 4 is a diagrammatic block diagram of the electronic components of the calculator apparatus, and, Figures 5, 6 and 7 are views corresponding to Figure 2 of the display and first keyboard as used during three alternative modes of calculation, repsectively average life mode, yield mode and convertible mode.

In the Figures there is shown a calculator apparatus 10 comprising a portable plastic box within which is mounted a power supply in the form of batteries 11. There is also provided an ON/OFF switch 12 and on the front of the calculator apparatus is provided an LCD display 13, a first keyboard 14 and a second keyboard 15.

In Figure 2 all of the characters which may be displayed are shown (although it will be understood that at any one time only a few of the characters are in fact displayed). At the top of the display 13 is provided an alphanumeric display 16 which can provide up to ten alphanumeric characters 1 6A together with floating decimal points 16B and sign 16C (plus/minus). There is also a display 17 indicating a "value date" and an arrow index 18 which can appear in positions 18A, B, C, D or E. Alongside position 18B there are two alternative displays 1 9A, 1 9B, indicating "360" or "365" respectively. Alongside position 1 8C there are two alternative displays 20A, 20B indicating "AIBD" or "ALT". Alongside position 1 8D there are two alternative displays 21A, 21 B indicating "SEMI" or "ANN".Alongside position 18E there are two alternative displays 22A, 22B indicating "DEC" or "Y.D".

In practice with respect to displays 21A, 21 B there will be indicated as alternatives the words "SEMI ANN" or ANN".

Also forming part of the display 13 are fourteen symbols 25 to 38 which correspond in layout to the layout of keys 125 to 138 of the first keyboard 14. Each symbol 25 to 38 is in two parts, that is, for example symbol 25 comprises a rectangular outline 25A and an inner indicator 25B.

At the right of the display 13 there is a display 40 reading "MODE" and below this are set out four displays 41 to 44 reading respectively, "SET", "AVL", "YLD", "CNV".

The layout and characters engraved on each key 120 to 141 of the first keyboard are clear from Figure 2 and will not be described in detail except that the characters on the keys are all in white except for the following two groups, the first group (comprising the upper characters on keys 125, 126, 130, 131, 135, 136, 137) are yellow and the second group (comprising the upper characters on the keys 127, 128, 129, 132 133, 134) are blue.

Figure 4 shows a block diagram of the electronics of the calculator. This Figure is divided into a number of sections, section 200 being power supply section, section 220 the display section, 240 the keyboard section, 260 the "slow" microprocessor section, 280 the "fast" microprocessor section.

Most of the components will be apparent from Figure 4. However in the display section 220 there is provided the LCD display 13 which is driven by four registers 221 to 224.

The keyboard section 240 includes a fortyfive key matrix 241 connected to the first and second keyboards 14, 15. In the slow microprocessor section 260 there is provided a model 1802 microprocessor 261 of the CMOS type which acts as a central processing unit for that section and there are included various registers in the form of 2 RAMS 262,263 (random access memories) and an EPROM 264 (erasable programmable memory).265 is a six bit latch. There is an output line 266 from the microprocessor 261 to the power supply section 200. There is also provided an oscillator 267.

The fast microprocessor section 280 includes a high power consuming high rate of operation model INTEL 8088 microprocessor 281 driven by a clock generator 282, the section including a latch 283, EPROM 284.

Power to the microprocessor 281 is provided by line 285.

The power supply section 200 includes a battery charger circuit 201, rechargeable batteries 11, ON/OFF switch 12 and various regulators one of which includes a switch unit 203 controlled by signals from the microprocessor 261 along line 266 to switch power to the fast microprocessor section along line 285. Power is continuously supplied (when ON/OFF switch is on) along line 286 to the slow microprocessor section 260 and at all times (even when ON/OFF switch is off) along line 287 to the RAM.

For ease of understanding we herewith set out the meaning of the characters on each of the keys where not immediately obvious.

MOD = Mode SET = Set (to set the alternative displays 19 to 22, that is 360/365, AIBD/ALT, SEMI/ANN, DECND.

NXT = Next (advances arrow index 18 through positions 18Ato E.) Yield Mode (YLD on display 43) ACC = Accrued interest % CYL = Current yield % MDT = Maturity date CPN = Annual coupon rate % PRI = Price % CIP = Change in price % ALY = Average life yield % MYL = Maturityyield % FRO = frequency (ie number of times per year a bond pays interest) RDP = redemption price % VAR = variation in yield % ALF = average life (in years) AVP = average price % LIF = whole life (in years) Average Life Mode bA VL) on Display 42) NPY = number of sinking fund payments SFA = sinking fund amount RDP = redemption price % SMO = number of months between sinking fund payments SDT = sinking fund start date ALF = average life (in years) AVP = average price % Convertible Mode (CNV on Display 44) FEX = fixed exchange rate CVP = conversion price PRI = bond price % CEX = current exchange rate PRM = premium/discount% SHP = share price CAL = calculate DIS = display CLR = clear CNS = consideration DIF = difference between dates SwA = semi-annual/annual conversion 360/365 = Number of days in year of calculation (Eurobond market reckons on 12x30 days month per year) AIBDIALT = Association of International Bond Dealers Method of accrued interest calculation/alternative method - eg US Treasury Bill method as per altern ative programme.

SEMI/ANN = Method of compounding interest payments in redemption yield calculations - either semi-annual or annual.

DECN.D = Method by which lives are stored and displayed. Either in decimal years (4.5=4 years) or years and days (4.182 = 4 years 182 days).

VALUE = Date on which deal is effected DATE generally 7 days hence.

The depression of one of the three keys 139, 140, 141 followed by one of the fourteen memory related keys 125 to 138 has the effect of, if the key DlS(1 41) is pressed displaying the information in the memory related key register, if key CLR(140) is depressed clearing the register associated with the key 125 to 138 or if key CAL(139) is depressed calculating the related variable. In the latter case the value both appears on the display 13 and is stored in the internal memory location associated with the key 125 to 138.

The second keyboard provides the kind of facilities found in most calculators plus three specialised arithmetic functions key CNS(150), key DIF(151) and keySeA(152)which operate on the display 13 without influencing any internal memories.

Other keys provided in the second keyboard are key "." (153) and key "1/16" (154) and key "1/32" (155).

These are used to calculate for example sixteenths or thirty seconds as follows. To produce the decimal equivalent of for example 5 15/16, one depresses 5.15 1/16 and the display will indicate 5.9375.

We will now describe the method of operation of the calculator. The two keyboards have three main sections. The three keys 120, 121, 122 at the extreme left of the first keyboard control the mode of the machine and also establish the fundamental calculation criteria. The remaining keys 125 to 141 of the first keyboard control the transfer of data between the display 13 and the memory locations in the rams 262,263.

The mode of operation of the calculator will be more easily understood with respect to the following three calculations carried out on a sample bond. The sample bond has the following features.

1. Face value $1,000.

2. Matures on 15 June 1989.

3. Pays interest of 14% annually on 15 June.

4. It has a sinking fund. Sinking fund commences 15June 1985 to repay the entire issue in five annual instalments of 20% each.

5. Market price of the bond is $980 (ie 98% of face value).

Yield Mode Calculation Question: What is the redemption yield? Press the keys in the following sequence.

SET NXT (until arrow index 18 is at position 18B.

SET This is a Euro bond and so press SET until 360 appears) NXT (until arrow index 18 is at position 18C when press SET to select display AIBD) NXT (press SET to select display ANN) NXT (press key SET to select display Y.D) MOD (press until display 43 YLD appears, ie calculator is now in yield mode. The display 13 will then be in the form indicated in Figure 6 and all of the outlines 25A to 38A will be indicated. However, none of the indicators 25B to 38B are shown at this present time.) 14 CPN (ie 14% coupon rate. At this point the indicator 28B appears on the display which shows the data from key 128 has been entered).

98 PRI (ie 98 price %. At this point the indicator 29B appears on the display which shows the data from key 129 has been entered) 6.15.89 (ie maturity date 15June 1989. At this MDT point the indicator 27B appears on the display which shows the data from key 127 has been entered) CAL MYL (ie calculate maturity yield. Display then indicates "CHOOSE" and the indicators 27B (MDT) and 38B (LIF) pulsate. This means that MDT or LIF keys must be pressed depending upon which yield calculation is required.

MDT (display then shows 14.364. This is the answer, the yield rate %).

Convertible Mode If the bond mentioned is above is convertible into common stock of the issuing company on the basis of 25 shares for one bond and the shares in that company are, today, $43 we wish to calculate whether it is better if we wish to buy shares in the company to buy them directly or to buy convertible bonds and convert them into shares. In the manner already described we get the calculator into the CNV mode, that is, the display 44 must be present. In this case the display 13 will appear as in Figure 7 when only the keys 127, 128, 129,132, 133, 134 are required. The keys are operated in the following sequence.

40 CVP (ie conversion price $40. At this point the indicator 28B appears on the display which shows the data from key 128 has been entered).

43 SHP (ie share price $43. At this point the indicator 34B appears on the display which shows the data from key 134 has been entered).

98 PRI (ie bond price 98% of face value. At this point the indicator 29B appears on the display which shows the data from key 129 has been entered).

CAL PRM (ie calculate the premium or discount ie % by which it is better or worse to buy the bond and convert rather than to buy common stock directly. The display shows 8.571 - ie it is better by 8.571% to buy the convertible share and convert than to buy the common stock direct.

Average Life Mode With the same bond as before we wish to calculate the so-calied average life. As part of the bond is redeemed earlier than the final term then one can consider it as having average life less than the full term and base one's calculations on this average life. A simple example is given here with a sinking fund which pays back 20 per annum but there are often more than one sinking fund so that there are different amounts paid back in different years.

The calculator should be operated so as to be in the average life mode (AVL display 42) showing. The display will then be as in Figure 5 with keys 125, 126, 130, 131, 135, 136, 137 in operation.

The keys are operated as follows.

6.15.85 SDT (ie sinking fund start date. Indicator 25B pulsates thereby guiding the user to insert the number of payments in the sinking fund. There are five payments and so you press keys as follows.

5 NPY (the indicator 26B now pulsates requesting us to insert the sinking fund amount as follows:) 20 SFA (ie sinking fund amount 20%. The indicator 31 B now pulsates thereby asking us how many months between payments. In this case there are 12 months between payments and in fact the calculator is programmed so that it automatically displays 12 on the display 16 since this is the usual number of months.

Simply pressing SMO will then insert the 12 but if the number of months has been changed, is six, not twelve, then one would have to press 6 SMO).

SMO Indicator 30B now pulsates. This is asking for the redemption price %. In this case it is 100% and so as with the 12 monthly indication the display 16 indicates 100 since this is the normal percentage. It is only necessary to press RDP but if the percentage had been different then one would have inserted the number and then pressed key RDP.

RDP Repeat above entries for different schedules of sinking fund payments until all are entered. In the present case there is one single schedule which has already been entered but when all the schedules have been entered press keys as follows.

CAL AVF The display 16 will then show a figure which is the average life. In the present instance the figure will 7.50.

We now need to know the redemption yield to that date. The calculator is then returned to the Yield Mode shown in Figure 6. Keys CAL and AVL are then pressed and the calculator calculates the yield to that average life data and displays it on display 16.

It will be noted therefore that the symbols 25 to 38 have carried out three functions during these calculations. Firstly, they have indicated which information is necessary for a particular calculation.

Secondly, they have indicated for example when indicators 25 to 38B are present that information has been entered by the key corresponding to that indicator and that that information has been passed to the memory corresponding to that particular key. In the third mode of operation (particularly present in the average life mode), the indicators 25 to 38B when pulsating have indicated which information is next required and have led the person carrying out the calculation through the calculation.

In broad terms, the electronics which are shown in Figure 4 operate as follows. When the apparatus is switched on power is applied to the microprocessor 261. As information is keyed into the keyboard through the matrix 241 the information is operated on by the microprocessor 261 which controls the keyboard and the various memories 262, 263 in accordance with the programme in the EPROM 264 and the information which is to be displayed is passed to the display 13 through the registers 221 to 224. When however a calculation is to be carried out (and in the present arrangement when any calculation is to be carried out although of course the arrangement could be such that some more minor calculations are carried out in the microprocessor 261) the microprocessor 261 through the line 266 switches on the power supply to the high speed microprocessor 281.This microprocessor 281, after an initial checking period, utilises the information in the registers 262, 263, 264 and operating through its own EPROM 284 carries out the necessary calculations. When the calculations have been completed they are passed back to the slow microprocessor section 260 and display section 220 so that the result is displayed on the display 13. When the calculation has been completed the power supply to the microprocessor 281 is switched off.

The invention is not restricted to the details of the foregoing example. Clearly, with different programmes and with a different display such a calculator can be used to carry out other complex calculations in the fields of mathematical analysis, scientific analysis, hire purchase or mortgage calculations and the like.

The principle of carrying out the complex calculations in a high speed microprocessor which is only switched on whilst carrying out the calculations and the other functions and then perhaps some minor calculations being carried out by the low power consuming slow speed microprocessor is widely applicable.

Furthermore, the use on the display of indications relating to the keys so as for example to select which keys are to be used in a particular calculation and to indicate which keys have already been operated or which keys are to be operated has widespread uses also with or without the use of the splitting of functions between the high speed and low speed microprocessors.

CLAIMS (Filed on 8 June 1982) 1. A calculator apparatus including a keyboard, and a display, the display including an indication of at least part of the keyboard, and means to operate the display so that, the indication of the keyboard indicates (a) the keys which will be used during a particular selected calculation and/or (b) which key or keys is/are to be pressed next in order to continue the calculation and/or (c) which keys have already been pressed to avoid inserting the same information more than once.

2. A calculator as claimed in claim 1 in which the keyboard comprises a first keyboard including keys through which functional data may be entered and a second keyboard including numerical keys through which numerical data may be entered.

3. A calculator as claimed in claim 2 in which the display includes an indication of the first keyboard only.

4. A calculator as claimed in any of claims 1 to 3 in which the display includes, for each key illustrated, two parts, one indicating an outline of the key itself and the other indicating either which key or keys is/are to be pressed next in order to continue the calculation and/or which keys have already been pressed to avoid inserting the same information more than once.

5. A calculator as claimed in claim 2 in which at least one of the keys in the second keyboard determines the type of calculation to be carried out.

6. A calculator apparatus as claimed in any of claims 1 to 5 comprising a portable calculator having a power supply, a relatively high speed, a relatively high power processing unit, a relatively low speed, relatively low power processing unit, and means to provide that all the relatively high speed relatively high power processing unit is only powered during calculations on that high power processing unit.

7. A calculator apparatus as claimed in claim 1 substantially as hereinbefore described with reference to the drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. microprocessor 261) the microprocessor 261 through the line 266 switches on the power supply to the high speed microprocessor 281. This microprocessor 281, after an initial checking period, utilises the information in the registers 262, 263, 264 and operating through its own EPROM 284 carries out the necessary calculations. When the calculations have been completed they are passed back to the slow microprocessor section 260 and display section 220 so that the result is displayed on the display 13. When the calculation has been completed the power supply to the microprocessor 281 is switched off. The invention is not restricted to the details of the foregoing example. Clearly, with different programmes and with a different display such a calculator can be used to carry out other complex calculations in the fields of mathematical analysis, scientific analysis, hire purchase or mortgage calculations and the like. The principle of carrying out the complex calculations in a high speed microprocessor which is only switched on whilst carrying out the calculations and the other functions and then perhaps some minor calculations being carried out by the low power consuming slow speed microprocessor is widely applicable. Furthermore, the use on the display of indications relating to the keys so as for example to select which keys are to be used in a particular calculation and to indicate which keys have already been operated or which keys are to be operated has widespread uses also with or without the use of the splitting of functions between the high speed and low speed microprocessors. CLAIMS (Filed on 8 June 1982)

1. A calculator apparatus including a keyboard, and a display, the display including an indication of at least part of the keyboard, and means to operate the display so that, the indication of the keyboard indicates (a) the keys which will be used during a particular selected calculation and/or (b) which key or keys is/are to be pressed next in order to continue the calculation and/or (c) which keys have already been pressed to avoid inserting the same information more than once.

2. A calculator as claimed in claim 1 in which the keyboard comprises a first keyboard including keys through which functional data may be entered and a second keyboard including numerical keys through which numerical data may be entered.

3. A calculator as claimed in claim 2 in which the display includes an indication of the first keyboard only.

4. A calculator as claimed in any of claims 1 to 3 in which the display includes, for each key illustrated, two parts, one indicating an outline of the key itself and the other indicating either which key or keys is/are to be pressed next in order to continue the calculation and/or which keys have already been pressed to avoid inserting the same information more than once.

5. A calculator as claimed in claim 2 in which at least one of the keys in the second keyboard determines the type of calculation to be carried out.

6. A calculator apparatus as claimed in any of claims 1 to 5 comprising a portable calculator having a power supply, a relatively high speed, a relatively high power processing unit, a relatively low speed, relatively low power processing unit, and means to provide that all the relatively high speed relatively high power processing unit is only powered during calculations on that high power processing unit.

7. A calculator apparatus as claimed in claim 1 substantially as hereinbefore described with reference to the drawings.