Augi, Jeffrey, Peyton, Toni
Reverse Engineering Step by Step
Topic: Calculator

Step 1. Identify the purpose
●	We want to learn about each part of the calculator and its purpose. We also want to know how each part works with each other.

Step 2: Developing a hypothesis- 
If the circuit board receives a message from the keyboard, then it translates the message on the screen.
❖	How does the circuit board work?
❖	How does the screen work?
❖	How does a circuit board translate into a LCD screen?
❖	How does the circuit board and the rubber buttons work together?

Step 3: Disassembly

Step 4: Analyze the Elements

Purpose and function: 
The purpose of this object is to calculate math equations using buttons and a circuit board.  The basic function is to add numbers, so that humans don’t need to solve it with writing.  It is made to save time and limit the amount of mathematical errors. 

Materials:
●	The protective Plastic empty husk (protective piece): holds the calculator together
●	Circuit board: board that computes all equations
●	Connective paper: connects the circuit board to screen
●	Screen: shows all numbers added or subtracted and a solution
●	Backboard: holds calculator together and protects circuit board
●	Wires: connects the circuit board to the metal sides
●	Metal sides: connect to the core (power source)
●	Button cell: is the battery or power source of calculator
●	Screws: holds together the protective piece
●	Protective cover: holds the power or button cell in place
●	Rubber button sheet: allows use of circuit board
●	Stubble indent: holds the calculator in place
 
●	 Identification numbers
●	 212l: type of calculator ( scientific)ber
●	20040522:identification number aka tracking num

Materials of each element:
●	The protective empty husk (protective piece): Plastic
●	Circuit board: made of copper with plastic covering them
●	Connective paper: plastic and copper
●	Screen: (LED): semiconductor chip which is surrounded by a transparent plastic case.
●	Backboard: plastic
●	Wires: copper covered in rubber
●	Metal sides: copper mixed with tin (because it has a silver color)
●	Button cell: alkaline 
●	Screws: stainless steel
●	The protective cover: plastic (Polyethylene terephthalate (PETE or PET))
●	Rubber button sheet: rubber 
●	Stubble ident: Made out of plastic
 
Price: $2.69
Is it recyclable: It is, A lot of recycle centers for calculators have sprouted up.One  is called N. regional California center and it is located in 1650 Bell Ave, Sacramento, CA 95838, USA

How everything works
❖	How is the calculator powered?
The button cell holds a charge. Since its connected to conductive wires, electricity goes from the button cell to the circuit board and screen in a closed circuit.
❖	How does the circuit board and the rubber buttons work together?
You press on the rubber buttons and compress it into the circuit board. The rubber button pushes down making an electrical contact between 2 layers in the keyboard sensor underneath and the keyboard detects this. The circuit board computes what button you pressed on and then displays it.
❖	How does the circuit board work? 
Circuit boards, also known as a printed circuit board, are thin plates with electronic components found in most communication devices.  These devices include computers, cell phones, and calculators.  Circuit boards have circuitry that connect the main components together.  These components are memory chips, processors, input/output devices, and resistors and capacitor.   The board uses these components to transfer information and signals in between each other as well as to external devices.  
❖	How does the screen work?
 Unlike the modern century calculators; which has millions of pixels in it, the 19th century calculators have a lot less; yet, can still display few letters. The difference between early computers and modern LCD calculators is that the computers were made of few pixels and looked very grainy, while the modern calculators have a lot more of pixels which would be the reason why the screen almost looks like a book. The processor chip is apart of the display screen, it knows it can input numbers between 0-9; thus, displaying letters on the screen. The modern scientific calculators obviously can say a lot more. 
❖	How does a circuit board translate a message into the LCD screen?
In electronics, the circuit board is the “brain” of the machine. It tells the rest of the machine what to do, in this case it tells the screen what to display. First, the circuit board receives the input from the button press. It then sends a signal through the conductors in the board to the screen receiver. The screen receives the message and displays the message. This process requires power from the battery. 

1)	How each part fits to each parts fit together
2)	How does it turn on
3)	What is the mechanism to do that

*https://www.techwalla.com/articles/what-are-the-functions-of-a-circuit-board 
*https://www.techwalla.com/articles/how-does-a-printed-circuit-board-work 
*https://www.explainthatstuff.com/lcdtv.html 
*https://www.explainthatstuff.com/calculators.html  
http://getcircuitdiagram.today/electrical-schematic-calculator.html