I have always wanted to have a real, hold-in-my-hand programmer calculator. Software calculators just aren't very exciting for me. So I set out to create my own! This is a project I've been working on since a few years ago, but only recently did I dig up the gumption to finally finish it off.

It is a custom PCB surrounded by a 3D printed ABS case with 3D printed buttons (don't even ask how many button iterations I went through) each with a drawn-on label. The screen is 16 7-segment displays, 8 for the top row and 8 for the bottom row to display 2 32 bit numbers, and 64 individual red LEDs to display the binary representation of the same 2 32 bit numbers. The brain is an ATMEGA 128 because I wanted the extra IO for the button matrix and keypad LEDs. Right now it only operates off of USB power, but once I find a PowerBoost 1000c to disassemble, it will have an internal battery.

It can display and receive numbers in decimal, binary, and hex, as well as doing all the necessary integer operations and bitwise operations. The calculator operates using Reverse Polish Notation. The two numbers displayed are the two top numbers on the stack (the bottom number is the top of the stack.) Single operand operations such as bit shifting, 2^x, 1's and 2's compliment are done on the number on the top of the stack.

It measures 3.05" x 4.7" x 0.6". I heavily based its looks off of old Commodore calculators with red LED screens and colorful buttons.

Here is a picture! (Click to enlarge)

Pretty sure a lot of people here will love this. I like the look personally and how you managed to accomplish something few people did with similar projects: Actually make a prototype or finish it.

Oh snap, this looks absolutely amazing! Those retro 7-segment displays and binary readout underneath really complete the aesthetics. Will you be writing up more of the project (schematics, PCB layout, software, and/or build log) at some point?

That's a pretty nice pet / learning project, indeed - the result looks good

Thanks! I think I will once I make sure that the battery charging circuit works. Also there are a couple corrections I need to make to the pcb layout as you can tell by the bodge wires up by the upper right 7-segment display. It certainly is nice to finally have it working. The whole screen (7segs and binary led's) is multiplexed and it's certainly pushing the limits of a 16MHz microcontroller. Luckily you can't see the flashing just by looking at it.

Looks very awesome and retro - I had never thought about a hardware programmers calculator before, I really like the concept!