Scientific Calculators

That's a bit like asking how the computer you used to post this question works!

Its rather more complicated than a simple answer can say.

John.

Go to a library or on the Internet, do your research, it will reward you for asking the question.

http://en.wikipedia.org/wiki/Alan_Turing

As other people wrote,this is a rather wide subject,but I think it's a good practice to acquire his or hers own knowledge,doing things.
As Confucius said(in IEEE Computers magazine),what I Do,I know.

You could:

1)using a 4 operations calculator(in the 1 to 3$ range) with a LED display,build your own 7 segments to BCD translator(using TTL or CMOS),and write in registers,such as 74LS75 or 74LS373

2)take a scientific low cost calculator such as HP25 or TI35,and add your own logic to perform scientific calculation(sinus,logarithms)directly in your own registers.
You can convert to analog signals withs DACs,and write directly the result in a XY plotter

3)you can,the same way,add registers,memories,ADC,DAC and EPROMS to low cost ancient devices such as ALICE or SINCLAIR ZX81

4)I recently found in a garbage a microcontroller card with a COP420,and in another garbage,a DVD supply working(°3V3,+5V,+/-9V).That's a low cost inititiation to microcontrollers.

everything ya wrote is sort of lame, don't ya think. Why not start from scratch and build ya own simple adder circuit, ya can do the math in BCD, then move on to building a simple cpu from scratch as well like a real soon to be eng would love to do, then all other answer fall in line from there. But like most EEE, if its too hard then its not worth doing, and then fall on answers like this.

Please tell us the reason for your question in the first place.....

This is a student, lay off your egos and help.

This search engine may help.

www.scirus.com

Makar, you are totally out of line with your interrupt (comment!).

If you are knowledgeable in this area, you would be better off contributing that knowledge as a post....before criticising anyone else.....

Knowing the reasons behind the question is a viable form of help....in fact, it speeds up the help considerably!

A good place to start would be Texas Instruments website or do a search on a TI-5, or TI-55, any of the model numbers for a Texas instrument calculator. They were the first company to develop calculators. A drafting teacher in high school had the first one every made. I think it cost him close to $300.

Little help (basic logic required):

Here is a building block of arithmetic unit in your calculator/computer: Adder

In binary system you want to perform :

0 + 0 and get 00 as a result

0 + 1 and get 01 as a result

1 + 0 and get 01 as a result

1 + 1 and get 10 as a result

summarize above in the table you got

| A | B | C | S |

| 0 | 0 | 0 | 0 |

| 0 | 1 | 0 | 1 |

| 1 | 0 | 0 | 1 |

| 1 | 1 | 1 | 0 |

Let A and B variables to add up, and S for sum and C for carry.

You should find that literally

C is A AND B,

S is A XOR B

and graphically:

The above circuitry is called half adder (HA), it is suitable for A and B both are 1 bit variable, meaning that each can only hold value 0 or 1.

Does above short article give you a sight?

For higher quantity of A and B you use another type off adder, called Full Adder (FA), a little more complicated but powerful. The FA circuitry will be attached on demand.