## Composition structure

Calculators are generally composed of arithmetic unit, controller, memory, keyboard, display, power supply, and some optional peripheral equipment and electronic accessories, which are composed of manual or mechanical equipment. The arithmetic unit and controller of the low-end calculator are realized by the digital logic circuit for simple serial operation, and the random access memory has only one or two units for accumulative storage. High-end calculators are implemented by microprocessors and read-only memory for various complex calculation programs, and there are more random storage units to store input programs and data. The keyboard is the input part of the calculator, and generally adopts the contact type or the sensor type. To reduce the size of the calculator, one key often has multiple functions. The display is the output part of the calculator, such as a light-emitting diode display or a liquid crystal display. Integrated circuit (see complementary metal-oxide-semiconductor integrated circuit), and is equipped with an automatic power-off circuit that does not operate at a fixed time. The peripherals available for the calculator include micro printers, cassette tape drives, and magnetic card players.

From a certain perspective, "computer" in a broad sense includes "electronic calculator". There are also integrated circuits in electronic calculators, but calculators have simple functions and cheaper prices, which are good for portability and good stability.

In the past, books such as abacus, Napier bones, math table books, engineering slide rules or mechanical adding machines played an auxiliary role in numerical calculations. The term calculator originally refers to professionals who run mathematical calculations with pen and paper. Such semi-manual calculations are burdensome and error-prone.

Modern calculators are powered by electricity and have a variety of shapes and sizes, from cheap, credit card-sized simple devices to special calculators with printing functions.

## Origin and development

### Primitive development

Calculator is the earliest calculation tool, for example: Quipu or khipu is a kind of knot of ancient Incas The method of rope recording, used to count or record history. It is made of knots of many colors.

There are also the Antikythera device of the ancient Greeks and the Chinese abacus. One of the earliest calculation tools used in ancient China was called plan, also known as calculation plan. This kind of calculator is mostly made of bamboo, but also wood and animal bones as materials. A bunch of about two hundred and seventy, put it in a cloth bag and carry it with you. The abacus that is still in use today is another invention in the field of ancient Chinese calculation tools. The abacus in the Ming Dynasty is almost the same as the modern abacus.

### Modern Development

Early calculators were purely manual, such as abacus and calculator. The abacus is usually made of sliding beads. In the West, the abacus was used for centuries before Indian Arabic numerals became popular, and it is still widely used in modern Chinese accounting and business. Later, mechanical calculators appeared. At the beginning of the 17th century, the calculation tools of Western countries have developed greatly. The "Napier calculation chip" invented by the British mathematician Napier, and the British priest Ochoder invented the cylindrical logarithmic slide rule. This kind of slide rule is not only It can do addition, subtraction, multiplication, division, power, square extraction, and even calculate trigonometric functions, exponential functions and logarithmic functions. These calculation tools not only promote the development of calculators, but also lay a good foundation for the development of modern calculators. Computing tools are widely used in modern society.

In 1642, Pascaline, a great French scientist who was only 19 years old, invented the first mechanical calculator. In his calculator, there are some interlocking gears, one of which has turned ten. A bit of gear will turn another gear by one. People can dial in numbers like dialing a telephone dial, and the calculation result will be displayed in another window, but only addition and subtraction can be done. In 1694, Leibniz (Leibniz) in Germany improved it to be able to multiply and divide calculations. Since then, electronic calculators did not appear until the end of the 1950s.

In the 19th century, Babbage advanced the concept of computing tools and tried to create the first programmable calculator, but the machine he built was too heavy to operate.

In the 20th century, since the 1970s, microprocessor technology was incorporated into the calculator manufacturing process. The original microprocessor was produced by Intel in 1971 for a Japanese calculator company called Busicom (ビジコン) Yes, in 1972, HP launched the first handheld scientific calculator HP-35.

## Function type

**Classification according to manifestation**

Physical calculator, this type of calculator is generally Hand-held calculators are easy to carry and use, but in general, the functions are simpler and it is not convenient to upgrade the functions. There are also a few powerful graphical handheld calculators, but because the price is the most expensive, they are on the tablet With the popularity of computers and smart phones, it is not recommended to buy the most expensive multi-function handheld calculator.

Calculators in the form of software. This type of calculator exists as software and can Use on PC or smart phone, tablet computer. This type of calculator has many functions, and the function can be expanded by software upgrade. With the popularity of tablets and smart phones, the application of calculators in the form of software will become more and more, eventually It is expected to replace traditional handheld calculators.

Calculations in the form of software can generally be divided into three categories: common calculators, special calculators, and comprehensive function calculators.

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There are four types of common calculators:

①Arithmetic calculators-can add, subtract, multiply, Four simple operations such as division, also known as simple calculators. Generally physical calculators

②Scientific calculators-can perform operations such as powers, square roots, exponents, logarithms, trigonometric functions, statistics, etc., also known as functional calculators. It can be software or physical objects.

③Programmer's calculator-a calculator specially designed for programmers, the main feature is to support And, Or, Not, Xor: the most basic AND NOR and XOR operations, shift operations Lsh , Rsh: The full name is Left Shift and Right Shift, that is, left and right shift operations, you need to enter the number of digits you want to move (not greater than the maximum number of digits) RoL, RoR: the full name is Rotate Left and Rotate Right, for RoL In other words, it is to move one place to the left, and add the one that is moved out to the rightmost one. RoR is similar to

④ Statistical calculator - a calculation designed for people with statistical requirements The device can be software or physical objects.

### Special calculator

In addition to the commonly used calculators, there are also special calculators. There are especially many special calculators, such as personal income tax calculator, mortgage Calculators, fuel consumption calculators, etc. Generally exist in the form of software.

There is also a comprehensive function calculator (programmable calculator)

Such calculators generally exist in the form of software. In addition to the functions of commonly used calculators, users can also write programs or formulas by themselves, and store more complex calculation steps or formulas. It can be called later to perform repeated calculations, and even print the calculation process and results. Most of the functions of special calculators can be realized, such as personal income tax calculation, unit conversion, etc. can be programmed and calculated by the user. The user can also download the formula file made by others on the Internet for calculation. Comprehensive calculator It has a wide range of applications, not only for ordinary users, but also for programmers. It is more suitable for complex calculations in various design industries, such as construction, water conservancy, machinery, transmission, gears, structure, medicine, and even graduation design for college students, and elementary and middle school students. Using it to learn mathematical knowledge and some simple programming calculations is a representative of this type of calculator.

### Mechanical calculator

Mechanical calculator is a calculator that uses physical keyboard to input numbers and operation symbols, and uses mechanical parts to calculate. Before electronic calculators came out, mechanical calculators had always been the first choice for calculations. However, a certain failure rate led people to improve and invent electronic calculators.

### Electronic calculator

In the past, some calculators were as big as today’s computers. The first mechanical calculator was a desktop mechanical device, but it was quickly calculated by a desktop electrical machine. They were replaced by vacuum tubes, transistors, integrated circuit logic circuits and other materials in order. Most calculators today are palm-sized microelectronic devices.

### Basic calculator

In the past, some calculators were as big as today's computers. The first mechanical calculator was a desktop mechanical device, but it was quickly calculated by a desktop electrical machine. They were replaced by vacuum tubes, transistors, integrated circuit logic circuits and other materials in order. Most calculators today are palm-sized microelectronic devices.

The complexity of the calculator varies with the purpose of use. The simplest calculator module should contain the following components:

Power source, such as battery or solar panel (solar panel)

Display The screen, usually made of LED light source or LCD, can display a certain number of numbers (usually eight, ten, twelve, sixteen digits, with twelve digits being the most common)

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A key panel containing the following keys:

(1) Ten number keys, from 0 to 9

(2) Decimal point

(3) Equal to symbol, used to display calculation solution

(4) Four arithmetic functions (addition, subtraction, multiplication and division)

(5) Cancel key, used to clear the currently displayed number< /p>

(6)Power switch

(7) Other basic functions, such as square root or percentage key (%) p>

More advanced modules may have a single-value memory button (M+, M-), which can be called back when needed.

In the early 1980s, basic calculators began to be incorporated into other small devices, such as mobile phones, BBCall (pager) or wrist watches.

**Advanced****Electronic Calculator**

Advanced **Scientific Calculator** or **Engineering Calculator** supports trigonometric functions, statistics and other functions. The most advanced modern calculators can even display graphs and include a computer algebra system. This calculator can be programmed, and contains algebraic equation solvers, economic models and even game programs. This type of calculator can display a single value that fills the display. And the number can be expressed to 9.999999999*10 in scientific notation. If the user tries to enter a value that is too large or a calculation that produces a value that is too large (for example, enter **100!**, which is 100 factorial), the calculator will only display the word **error** . Because a calculator with such limited memory cannot store such a huge input (approximately 9.3326215443944 * 10 ^157).

**Error** is also used to indicate mathematically undefined functions or operations, such as dividing by zero or taking the square root of negative numbers (except for some expensive calculators that can handle complex numbers Special functions, most scientific calculators do not allow the existence of complex numbers). Some small calculators can distinguish the difference between these two errors, although it is still difficult for users to understand the difference between error 1 and error 2.

Only a few companies develop and manufacture calculators used by modern professional engineers and economists: the most famous ones are Casio, Sharp, HP and Texas Instruments. These calculators are the paradigm of embedded systems.

**Windows calculator**

It comes with a calculator in the windows system, and can switch between a simple calculator and a scientific calculator.

Open method:

1: Start-Program-Accessories-Calculator.

2: Start-run-enter "calc" to open it.

3: Call this machine program through the webpage to realize all the functions of the calculator.

After opening the program, you can click "View"-to switch between scientific type/standard type.

The calculator program that comes with the windows system is called calc.exe, and its path is X:\WINDOWS\system32\calc.exe. ("X" represents the symbol of the system disk)

You can use the mouse to click the buttons to perform operations during calculation, or you can use the keys on the numeric keypad to perform operations when the numeric keypad of the keyboard is open.

Statistical calculation: It can calculate the sum and average of a series of data.

Scientific calculations: functions, logarithmic operations, factorial, power operations, etc. can be performed.

Number system conversion: It can convert between decimal, binary, octal, and hexadecimal integers.

There are many special symbols, for example: PI is equal to π, which means π=3.1415926``` or 6.283185``` or 9.424777```

ln is a natural pair In mathematics, ln(x) is the logarithm of x with e as the base, and the derivative function of f(x)=ln|x| is f'(x)=1/x.

log For example: lg5 is the logarithm with the base 10, and 10 can be omitted, which is equal to 0.698970.

sin ——The ratio of the opposite side of the angle A to the hypotenuse is called the sine of the angle A, denoted as sinA, that is, sinA=the opposite side/hypotenuse of the angle A

cos— —The law of cosines is an important theorem that reveals the relationship between the sides and angles of triangles. It can be used directly to solve a problem of finding the third side of a known triangle with two sides and the included angle, or finding the angle of the known three sides. If the law of cosines is modified and Appropriately shifted to other knowledge, it is more convenient and flexible to use.

tan——The tangent function is the ratio of the opposite side to the adjacent side in a right triangle.

n!-This is the factorial in mathematics.

And so on, these symbols are conducive to our calculations, and get the results quickly and easily.

**Calculator and electronic computer**

The biggest difference with electronic computer is:

Calculator is just a simple calculation tool, some The model has a function calculation function, and some models have a certain storage function, but generally only a few sets of data can be stored.

Computers have complex storage and control functions, and are more powerful. They are commonly called "computers" in China.

Calculators, like computers, can realize data entry, processing, storage and Output, but it is different from the computer because it cannot automatically realize these operations, and must be done by humans. The computer can automatically process by programming. Therefore, the difference between the two by the degree of automation lies in whether manual intervention is required.

In fact, there is another essential difference between the two. The calculator uses a solidified processing program, which can only complete specific calculation tasks; while the computer can expand its application fields infinitely with the help of operating system platforms and various application software and hardware. In other words, whether it has scalability is the essential difference between the two.

Single-chip microcomputer is also called single-chip microcontroller. It is not a chip that completes a certain logic function, but integrates a computer system on a chip. In a nutshell: a chip becomes a computer. In the hands of scientists and engineers who use computer applications and intelligent control, it has the same essence as computers and can develop applications for various electrical and electronic products, such as washing machines. But for users, they don’t need to know the interface and programming language of the MCU in the washing machine, as long as they can operate the laundry. Therefore, the MCU needs to be used with a simple and convenient human-machine interface for a specific electronic product. Only use its specific functions.

## How to buy

**1. Look at the speed**

The calculation speed of the calculator must be fast. It is also necessary to ensure that the number cannot be wrong.

**2. Flexible buttons**

The calculator must be pressed to get the number, otherwise it will be very troublesome.

**3. The screen is clear and has no traces**

The calculator must have a clear screen and no traces. Here is a method: 1. Press the number 8 continuously to check whether the number is complete. 2. Check whether the decimal point can be displayed (check every digit).

**4. Is the outer cover damaged?**

If it is damaged, do not buy it. It is possible that the electronic parts will fall off and damage the calculator.

## How to use

The calculator includes two types: standard type and scientific type. The standard type is used as follows:

1. When typing in a number, press the corresponding If you press the wrong number key, you can use the (CE) key to erase a value, and then re-enter the correct number.

2. After entering a number directly, press the multiplication sign to change it into a multiplier, and directly press the (=) key without entering the multiplicand, which is the quadratic value of the number.

3. The root sign (√) key defaults to open the second square root, and only scientific calculators can open the second square root.

4. Press the (+/-) key to change the positive or negative value of the number.

5. After entering the number and determining the operation symbol, pressing the (%) key will automatically assign the previous parameter to the percent of the previous parameter to participate in the calculation. Percentages under Windows 7 cannot directly participate in calculations. What is involved in calculations is a few percent of the previous operand. This is also the calculation in most mobile phones, such as 78+2 (%) is equivalent to 78+78*2%, and the final result is 79.56, such as NOKIA. Click it under xp and the program will multiply the two products and divide by 100, and display the result. For example, input 23+3, and then click "%", the result is 0.69. Enter 23-3, or 23/3, or 23*3, and then click "%", the result is still 0.69, which means it ignores the addition, subtraction, multiplication, and division signs. When using it, be sure to note that "%" can only be used after x+ (or -,*,/), or after the computer result, which means one-hundredth of the square of the calculated result.

6. Some standard models have digital storage functions, which include four buttons: MRC, M-, M+, and MU. After entering the number, press MS to read the number into the memory. No matter how many calculations are performed thereafter, just press MR once to read the previously stored number, press MC to delete the number from the memory, or press MRC twice. MU is the interest rate calculation, 2000[MU]20%=2000/(1-20%)=2500, 2000[MU][±]20%=2000/(1+20%)=1666.7.

The equal sign "*=" can also mean square: For the square of 10, you can press 10 and then × and then = and the result will be 100. But press 10, + and then = and the result is 20, that is, "+=" means 2 times, because it is equivalent to 10+10=20. Similarly, 10/= is equivalent to pressing 10/10=, and the result is 1.

## Troubleshooting

①The display is dim or sometimes bright and sometimes dark after booting. First, measure whether the voltage of the battery used is normal. If it is normal, you can further check whether the battery spring pressure is sufficient and whether the contact is good. If there is any problem, you can stretch the spring or use fine sand to polish the contact of the battery pole piece.

②There is a digital display after turning on the computer, but it cannot be calculated. Use a multimeter to check the circuit board to see if there is a short circuit between the terminals of the integrated circuit block. Use a multimeter to check the voltage value of the keyboard input terminal of the integrated block (24-29 pins for L1-3033E chip). The normal value should be about 0.12V, otherwise it may be possible. The manifold is broken. If the voltage is normal, but the operation cannot be performed, it may be due to poor keyboard contact, foreign matter on the circuit board, open circuit on the circuit board, or stuck keys.