NeoCal Documentation

NeoCal for Palm OS User Guide

Working Registers

NeoCal uses several registers for performing calculations with the most commonly used labeled x, y, and last x. The x register contains the number shown in the display, while the y register is paired with the x register when two values are required for a calculation or returned from a calculation. The last x register stores the value of the x register before the last numeric operation was performed.

As an example, let's add the numbers 12 and 15:

  1. Pressing places the number 12 in the x register.
  2. Pressing copies the value stored in the x register into the y register.
  3. Pressing stores the number 15 in the x register.
  4. Pressing adds the numbers in the x and y registers and places the result in the x register (which is shown on the display). The y register contains the value it contained before we started this calculation. The last x register contains the number 15.

Many keys are labeled with x () or x and y () referring to the x and y registers. The general rule is to enter the y value first, then the x value. Also,

  • Pressing the button will exchange or swap the values stored in the x and y registers. This is often used when two values are returned from an operation and you want to view the additional value.
  • Pressing the button recalls the value stored in the last x register into the x register. This allows a number to be used repeatedly without having to re-enter it.

The RPN input method also recognizes two more registers, z and t, which are discussed in RPN Tutorial.