X# Calculator Prototype
Operating Instructions

Introduction

The X# Calculator Prototype includes the extended numerical keyboard described in Patent No. 5,623,433. The extended keys [00], [000], and [6x0] are used to represent the quantities "hundred", "thousand" and "million" respectively. However, during the following description the symbols "H", "T" and "M" will be used to represent these keys.

This calculator also includes an additional memory key named the "Memory Swap Key [<-M->]."  This key will save the contents of the result in memory, and will bring the value stored in memory to the result display.  Notice that regular calculators only have a "Memory Recall" key, which will bring the value stored in memory to the display, erasing the value already accumulated in the display.

Displays

Every calculator has two registers, one to hold the number being entered (input register) and another to hold the current result value (accumulator register). Both are displayed in a single display, therefore, when a new data-entry operation is pressed, the new number replaces the accumulated value. To avoid this, the X-Number Calculator contains two displays:

x Result Display to display the accumulator register
n Input Display to display the input register

Every time a user starts a new data-entry operation, the new value is displayed in the Input Display as it is being entered. The value of the Result Display will be cleared automatically if no arithmetic operator preceded the data-entry operation, otherwise it will remain unchanged until the [=] or a new operator key [+ - / *] is pressed, at which time the Result Display will be updated and the Input Display will be cleared.

Try the following examples:

6 + 9 =
6 + 9 = / 3 - 1 =

The final value in the Result Display should be "4."

Structured Data-Entry

The X-Number calculator numerical keyboard will behave like any other standard 10-key pad.  When the user enters a number by using the ten-digit keys the data-entry behaves in the Conventional Mode, however, when any of the three structured keys: [00], [000], or [6x0] are pressed, the data-entry mode will be changed automatically to Structured Mode. This change will be reflected in the input display by showing a "#" symbol at the left side of the display when the Structured Mode is being used.  The data-entry mode can be changed at any time during the data entry operation by pressing the [X#] key.

While in Structured Mode, the data-entry can be done by pressing the [00], [000], or [6x0] keys to replace the words "Hundred", "Thousand" or "Million" within the verbal expression of the number. In many cases this could lead to a significant reduction in the number of keystrokes required to enter the number, for example, try the following sequence:

[M] 35 + 9 [T] 5 = [M+]
-3 [H] [T] 7 [H] + [T] [H] =

At the end of the sequence, the result display should show "709440."

The use of the structured procedure does not preclude the use of the conventional procedure during the course of the same number input operation. For example, the same result could be obtained by any of the following sequences:

23001207
23[M]1[T]2[H]7
23[M]1[T]207
23[M][T]2[H]7
23[M][T]207
23[M]1207.

Ten Key Pad and Dot Key

Notice that the Conventional Mode mode is the default mode, therefore the behavior of the ten digit keys is the same as any standard numerical keyboard.

The [dot] key is also the same - However, if the user is entering a number in Structured Mode, pressing the [dot] key will stop the Structured Mode. Decimals can only be entered in Standard Mode. Pressing an structure key after the decimal point is entered will append two, three or six decimal zeroes to the decimal portion of the number.

X# Key

The [X#] key is used to swap the data-entry mode in the Input Display.

To use the [X#] key, the Input Display must contain a value, this is because the calculator always start in Conventional Mode. Swapping the mode may be useful when the user wants to keep appending digits to the number after entering a value in structured mode. As example, try the following sequence:

3 [T] 1 [X#] 20 =

This will append the digits "2" and "0" to the number 3001 yielding "300120."

By the same token, if a number has been entered in Conventional Mode, pressing the [X#] key will change the mode to Structured Mode. As example, try the following sequence:

3001 [X#] 20 =

This will change "3001" to structured mode and will yield "3120."

Clear Key

The "CE/C" function key will clear the input display when pressed the first time, and will reset the device when pressed the second time.

CE Clear Entry
C Clear Result/Memory/All

Undo Key

The [Undo] key (left pointed arrow) will undo the effect of the previous keystrokes during a Data-Entry operation, or the effect of pressing an arithmetical operator.

Try the following sequence:

2 [M ] + 5 [T] 6 [Undo] [Undo] [H] * 3 [Undo]

At the end of the sequence, the Result Display should show "2000500."

Constant Key

The [K] key can be used at any time to set the calculator to "Constant Mode." This is indicated by the "K" icon in the Input Display.

While in "Constant Mode," the last entry will remain displayed in the Input Display, so that pressing the [=] key several times will repeat the displayed operation multiple times.

Try the following sequence:

20 + 5 [K] = = = [-] =

At the end of the sequence, the Result Display should show "30" and the Input Display should show the operation "-5" ready to be executed again if the [=] key is pressed.

Currency Key

The [$] key can be used at any time to cause all the operations to be rounded to two decimals (cents) and displayed as such in the Result Display. Notice that the intermediate results are not rounded, only the displayed value is rounded.

Try the following sequence:

20 / 3 = [$] [$]

the Result Display should show "6.67" after the first use of [$].

Operators

The behavior of the arithmetic operator keys [+ - / * ^] is the same as any standard calculator. The only difference is that one more operator has been added: [^].

The [^] key is the "power" operator. It allows to elevate the value in the Result Display to the power value entered in the Input Display. For Example:

2 ^ 3 =

will yield "8" in the Result Display.

Functions

The following functions are provided with the X-Number calculator:

[+/-] Changes the symbol in the Result Display.
[1/x] Replaces the Result Display with its Inverse value.
[Sqrt] Replaces the Result Display with its Square Root.
[%] Calculates the percent of the Result Display.

For Example:

4 ^ 2 = [Sqrt] [1/x] [+/-]

will yield "-0.25" in the Result Display.

Memory Operations

The X-Number calculator provide with five memory keys to handle its memory operations: [M+] [M-] [MR] [<-M->] and [MC].

As in most standard calculators, the Result Display shows an "M" icon whenever the memory value is different from zero.

The following are operations associated with the memory keys:

[M+] Adds the Result Display to the Memory
[M- ] Subtracts the Result Display from the Memory
[MR] Replaces the Result Display with the Memory value
[<-M->] Swaps the Result Display with the Memory value
[MC] Clears the Memory

Since the memory is basically an object, the following sequences are also valid:

[+][MR]= Adds the Memory to the Result Display
[- ][MR]= Subtracts the the Memory from the Result Display
[* ][MR]= Multiplies the Result Display by the Memory
[/ ][MR]= Divides the Result Display by the Memory
[^ ][M]= Elevates the Result Display to the power in Memory

Try the following sequence:

5 + 9 = [M+]
3 + 4 =
[<-M->] / [MR] =
[MC]

At the end of the sequence, the result display should show "2" and the memory should be empty.