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What steps do i have to take to make an electronic calculator?

Discussion in 'General Electronics Discussion' started by lonely_1, Jan 1, 2015.

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  1. lonely_1


    Jan 1, 2015
    I can program in C programming language, and have made a software calculator in that language, but i wish i could make an electronic one.
    I've found a picture from a website in which explains what we need to make an electronic calculator.


    I'm curious about how to program that processor chip! FYI, what i'm going to make, is not a Scientific or Standard Calculator - it's a Programmer Calculator (Where we got Dec, Hex, Bin, Oct, XOR, NOT, AND, OR, letters from A to F (for hex), parentheses, Mod, and so on.

    You know, i am not familiar with electronics, but i'm trying to. I always loved electronics. And i respect people who know electronics.

    So, a guide, tutorial, can really help.

    Thank you.
    Last edited: Jan 1, 2015
  2. hevans1944

    hevans1944 Hop - AC8NS

    Jun 21, 2012
    The first step I would take if I were you is a review of available calculators that perform the functions you want your calculator to perform. Then I would compare their selling price against the cost of building your own calculator. You will probably be able to cannibalize an inexpensive calculator to obtain parts, such as you illustrate in your very nice photo, so the really expensive part will be the design and construction of a circuit board that ties it all together: microprocessor, keyboard scanner, display driver, battery monitor, maybe a battery charger if your want to operate it like a cell phone with rechargeable lithium-ion cell(s).

    To get you started, I found this spiffy little programmers calculator made by the Japanese firm Casio Computers Ltd. with a suggested price of US$14.99. The clever engineers at Casio threw in a few extra features that you can examine by downloading the Manual and Additional Functions PDF files from the links on the web page.

    Their calculator doesn't need recharging from a wall outlet; it uses a solar cell array and an internal battery. I've used Casio calculators for about thirty years now and always found them to deliver good value. Of course, i still have no idea how to program a microprocessor to perform the things a hand-held calculator does, but I do know how to program a microprocessor to do all sorts of things that a hand-held calculator simply cannot do. I suggest, if you want to learn how to program microprocessors, that you start with any of the many microprocessor hardware and software development kits. These are incredibly affordable for the DIY electronics experimenter.

    On an historical note: I am fairly old. I started programming microprocessors for embedded system designs in the 1970s using the Intel 8080 8-bit microprocessor. One of the first things I programmed (just for fun, it had nothing to do with the project I was working on) was a decimal calculator that would add, subtract, multiply, and divide absurdly large decimal numbers. The 8080 happens to have a BCD arithmetic function that allows two unsigned BCD numbers, packed into a single byte, to be added or subtracted using two carry bits and some programming logic. Once the programming for that is nailed down it is almost trivial to dynamically extend the number of digits to any arbitrary length. Multiplication and division are more difficult since these functions have to be programmatically implemented. Early microprocessors had no multiply or divide instructions, meaning they are slow to multiply and divide, unless you forked over money for an arithmetic co-processor (which IIRC wasn't available for the 8080).

    Still, it was a lot of fun and a good way to learn assembly language. Today we have PICs, FPGAs, and 64-bit microprocessors to play with, along with gobs of free (or almost free) software in whatever language you feel is appropriate to the task at hand.

    Please keep us informed on what you decide to do with your project.
    Last edited: Jan 1, 2015
    KrisBlueNZ and lonely_1 like this.
  3. Laplace


    Apr 4, 2010
    As you see, a calculator is not much more than a keyboard, a display, and a microprocessor. If I were to try building such a calculator using the hobbyist parts I'm familiar with, it would probably end up being the size of a cigar box. However, if I wanted something small, sleek, and slim, then I would certainly want to reuse a cheap commercial calculator. However I suspect the problem with that might be that the processor is not a general-purpose device that is available for purchase but rather a custom LSI chip fabricated specifically for the calculator company and mask-programmed during fabrication. Furthermore the instructions for programming the chip may be proprietary intellectual property and a closely guarded secret. In that case the first thing I would do is investigate how difficult it would be to adapt a general-purpose microprocessor to function in place of the custom LSI chip. Have you ever tried taking a low cost calculator apart, including separating the edge connectors, then putting it back together? Did it still work?
  4. shumifan50


    Jan 16, 2014
    To learn how to program a calculator does not need to be done on a microprocessor, it can just as well be done on a desktop computer. Just make sure that you keep your interfaces to the real world in separate modules so they can easily be modified to suit the hardware you wish to run the final product on.
    There are so many VERY cheap calculators around that support the features you want to implement, that, unless it is purely for edification, you would be better off just buying one. If it is to understand the workings, then just do it on your desktop.
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