Appendix A: The Automatic Memory Stack 173

Pressing d four times successively displays the numbers in the Y-, Z-, and T-registers and returns the numbers to their original registers.

One-Number Functions and the Stack

One-number mathematics and number-alteration functions — y, r, °, >, e, B, Ñ, and T — use only the number in the displayed X-register. When the key is pressed, the function is performed upon the number in the X-register, and the answer is then placed into the X-register. The stack does not lift, so the number formerly in the X-register does not get copied into the Y-register; but this number is copied into the LAST X register. The numbers in the Y-, Z-, and T-registers are not affected when a one number function is performed.

Two-Number Functions and the Stack

Two-number functions — +, -, §, z, q, b, à, and Z — use the numbers in both the X- and the Y-registers.

Mathematics Functions

To perform an arithmetic operation, the numbers are positioned in the X- and Y-registers just as you would write them vertically on paper: the number you would write on top goes in the Y-register, and the number you would write on the bottom goes in the X-register. For example, to do each of the four arithmetic calculations shown below, you would put the 8 in the Y-register (using \and then key the 2 into the displayed X-register.)

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