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Chapter 48 ½ The HP Model 9100A Computing Calculator 789

Control and Arithmetic Keys

ADD, SUBTRACT, MULTIPLY, DIVIDE involve two numbers, so the first number must be moved from X to Y before the second is entered into X. After the two numbers have been entered, the appropriate operation can be performed. In the case of a DIVIDE, the dividend is entered into Y and the divisor into X. Then the [¸ ] key is pressed causing the quotient to appear in Y, leaving the divisor in X.

One way to transfer a number from the X register to the Y register is to use the double sized key, [­ ], at the left of the digit keys. This repeats the number in X into Y, leaving X unchanged; the number in Y goes to Z, and the number in Z is lost. Thus, when squaring or cubing a number, it is only necessary to follow [­ ] with [x] or [x] [x]. The [¯ ] key repeats a number in Z to Y leaving Z unchanged, the number in Y goes to X, and the number in X is lost, The [­ROLL] key rotates the number in the X and Y registers up and the number in Z down into X. [ROLL¯] rotates the numbers in Z and Y down and the number in X up into Z. [x®¬ y] interchanges the numbers in X and Y. Using the two ROLL keys and [x®¬ y],numbers can be placed in any order in the three registers.

Functions Available from the Keyboard

The group of keys at the far left of the keyboard, Fig. 4, gives a good indication of the power of the Model 9100A. Most of the common mathematical functions are available directly from the keyboard. Except for [½ y½ ] the function keys operate on the number in X replacing it with the function of that argument. The numbers in Y and Z are left unchanged. [Ö x] is located with another group of keys for convenience but operates the same way.

The circular functions operate with angles expressed in RADIANS or DEGREES as set by the switch above the keyboard. The sine, cosine, or tangent of an angle is taken with a single keystroke. There are no restrictions on direction, quadrant or number of revolutions of the angle. The inverse functions are obtained by using the [arcu ] key as a prefix. For instance, two key depressions are necessary to obtain the arc sin x :[arcu ][TAN x]. The angle obtained will he the standard principal value. In radians:

The hyperbolic sine, cosine, or tangent is obtained using the [hyperu ] key as a prefix. The inverse hyberbolic functions are obtained with three key depressions. Tanh-1 x is obtained by [arcu ][hyperu ][TAN x]. The arc and hyper keys prefix keys below them in their column.

Log x and ln x obtain the log to the base 10 and the log to the base e respectively. The inverse of the natural log is obtained with the ex key. These keys are useful when raising numbers to odd powers as shown in one of the examples on the pull-out card, Fig 3.

Two keys in this group are very useful in programs. [int x] take the integer part of the number in the X register which deletes the part of the number to the right of the decimal point. For example int(- 3. 1416) = - 3. [½ y½ ] forces the number in the Y register positive.

Storage Registers

Sixteen registers, in addition to X, Y, and Z, are available for storage. Fourteen of them, 0, 1, 2, 3, 4, 5, 6, 7, 5, 9, a, b, c, d, can be used to store either one constant or 14 program steps per register. The last registers, e and f are normally used only for constant storage since the program counter will not cycle into them. Special keys located in a block to the left of the digit keys are used to identify the lettered registers.

To store a number from the X register the key [x® ()] is used. The parenthesis indicates that another key depression, representing the storage register, is necessary to complete the transfer. For example, storing a number from the X register into register 8 requires two key depressions:[x® ()] [8].The X register remains unchanged. To store a number from Y register the key [y® ()] is used.

The contents of the alpha registers are recalled to X simply by pressing the keys a, b, c, d, e, and f. Recalling a number from a numbered register requires the use of the [x®¬ y] key to distinguish the recall procedure from digit entry. This key interchanges the number in the Y register with the number in the register indicated by the following keystroke, alpha or numeric, and is also useful in programs since neither number involved in the transfer is lost.

The CLEAR key sets the X, Y, and Z display registers and the f and e registers are set to zero to initialize them for use with the [ACC+] and [ACC-] keys as will be explained. In addition the CLEAR key clears the FLAG and the ARC and HYPER conditions, which often makes it a very useful first step in a program.

Coordinate Transformation and Complex Numbers

Vectors and complex numbers are easily handled using the keys in the column on the far left of the keyboard. Figure 5 defines the variables involved. Angles can be either in degrees or radians. To convert from rectangular to polar coordinates, with y in Y and x in X, press [TO POLAR]. Then the display shows q in Y and R in X. In converting from polar to rectangular coordinates, q is placed in Y, and R in X. [TO RECT] is pressed and the display shows yin Y and x in X.

ACC+ and ACC- allow addition or subtraction of vector components in the f and e storage registers. ACC+ adds the contents of the X and Y register to the numbers already stored in f and e respectively; ACC- subtracts them. The RCL key recalls the numbers in the f and e registers to X and Y.
 
 

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