How does a calculator work?

Answer 1

A modern electronic calculator is a microcomputer with a single unchangeable program stored in ROM. This program contains the keyboard and display device drivers and the algorithms to performs all the calculations that the calculator can do.

Some calculator manufacturers produce series of calculators using identical hardware and cases, the only differences between models in the series is: the program in the ROM, the keytop labels, and the model number printed on the case.

Answer 2

In general, a basic electronic calculator consists of the following components:

• Power source (battery or solar cell)
• Keypad - consists of keys used to input numbers and function commands (addition, multiplication, square-root, etc.)
• Processor chip (microprocessor) contains:
  • Scanning unit - when a calculator is powered on, it scans the keypad waiting to pick up an electrical signal when a key is pressed.
  • Encoder unit - converts the numbers and functions into binary code.
  • X register and Y register - They are number stores where numbers are stored temporarily while doing calculations. All numbers go into the X register first. The number in the X register is shown on the display.
  • Flag register - The function for the calculation is stored here until the calculator needs it.
  • Permanent memory (ROM)- The instructions for in-built functions (arithmetic operations, square roots, percentages, trigonometry etc.) are stored here in binary form. These instructions are "programs" stored permanently. Permanent memory cannot be erased.
  • User memory (RAM) - The store where numbers can be stored by the user. User memory contents can be changed or erased by the user.
  • Arithmetic logic unit (ALU) - The ALU executes all arithmetic and logic instructions, and provides the results in binary coded form.
  • Decoder unit - converts binary code into "decimal" numbers which can be displayed on the display unit.
• Display panel - displays input numbers, commands and results. Seven stripes (segments) are used to represent each digit in a basic calculator.

Answer 3

The same as your hand-held calculator. It quickly crunches numbers and displays them in a humanly readable format.