Re: i want to build a calculator that has at least 20 memory sections to it

My advice would be to avoid having an engineer build a calculator for 
you, unless you are a very excentric rich person who wishes this dream 
come true, or you plan on marketing this calculator as a new product.

Designing and building a hardware calculator would not be a simple or 
inexpensive task since you would basically have to pay a small team of 
engineers for several months of their times, which amounts to a six 
figure amount in US dollars. This pays off if you then successfully 
market and sell the product.

If you could manage to have a friend engineer to do it for you, by using 
a rapid prototyping method, perhaps using an inexpensive programable 
microcontroller (the ones you can program from a PC), a simple keypad and 
any of the available display screens, and if the functions were strictly 
limited to addition and display of a reduced number of digits, perhaps 
that would be doable in a series of weekends, although you would have to 
carry a clumsy home made device.

But all that aside, since you are asking this question online, I will 
assume you have access to a computer. I strongly encourage you to use one.

With a computer, probably the easiest way to accomplish what you want is 
to use a spreadsheet application such as Microsoft's Excel, I would 
suggest that you give it a chance and see if that works for you. The time 
it takes to input the numbers is no longer than with a calculator, plus 
you get to see the entire list in a column display that you can see and 
edit. The sum is updated automatically as you correct mistakes or change 
the numbers, and by using separate columns for each balance, you can have 
separate balances of separate numbers and remember absolutely every 
number you type, and their respective sums. Perhaps you can find a friend 
who already knows Excel and can show this to you, or you may be able to 
find an online tutorial.

However, if you prefer to have a calculator's user interface, an engineer 
might be able to write a software application to do just what you want on 
a desktop computer.

Although this is still a project for a weekend or two, it is easier than 
building actual hardware.

As I tried to answer your question, I assumed that somebody may have 
already written such a calculator, and I searched in a website 
www.download.com for the following keywords: "calculator" and "memory".

I found a program called "OC Scientific Calculator 2.0". You may be able 
to download it for free and try it out, or you may find other similar 
applications. I have not tried this, or any other calculator program, I 
will leave that up to you.

If you absolutely must have a portable machine for your calculations, my 
next suggestion would be to purchase a RPN scientific calculator (Like 
any of the Hewlett-Packard 48 series) and learn the Reverse Polish 
Notation on which they operate. This type of calculator uses the concept 
of a "stack" of numbers onto which you operate, and serves as a virtually 
large set of memory locations. Some people get used quickly to this 
system when solving engineering or scientific equations, but you should 
see for yourself if this notation feels natural for your particular needs.

Yet, another portable alternative might be a laptop computer running a 
custom made calculator or spreadsheet, just as I suggested before.

Hopefully I have given you an overview of what it takes to make a real 
calculator, and why that may not be the best approach, unless you are 
actually going for the fun of building something. I also hope 
my "lateral" suggestions are helpful to accomplish what you want quickly 
and easily with readily available software and hardware.

Good luck! - your mad scientist,

Aurelio Ramos