WRPN Architecture

WRPN uses 64 bit word variables as the internal representation for integer numbers. When dealing with floating point numbers, the numbers are stored in a typical 8 byte IEEE floating point format.

WRPN has 5 internal registers, 4 of which are arranged in a LIFO stack. They are:

• stack 3 (the T register)
• stack 2 (the Z register)
• stack 1 (the Y register)
• stack 0 (the X register)
• last x

Values pushed "off the top" of the stack (beyond stack 3) are lost. However, the value at the top of the stack is preserved when values are "popped".

The bottom of stack (the X register) is the value which is always shown in the display.

The Last X variable contains the previous value of the X register.

There are 5 flags:

• flag 1 User defined
• flag 2 User defined
• flag 3 When cleared, trim leading zeros from display
• flag 4 The "carry" bit
• flag 5 Overflow condition