NP-41 Emulator (may be)

[Chris Chung]

I agree w/ Eric and the NP-41 (and NP-25) are a very different class of projects. The DIY series is targeting usability, takes serious potential users input, with enhanced functionality and extension capabilities. It will be the calculator you can rely on for serious work.

The NP-xx is quite different. I create them just for fun. They are hobby grade w/ focus on building electronics than creating an everyday calculator. The keys are not comfortable, the LED are tiny and hard to read. And I actually enjoy building / designing them more that I use them. The project is satisfying to me on what I achieve technically, like the clever "1-wire" shift register usage on the NP-25 and the customized 14 segment LCD glass I am trying on the NP-41. Having said that I still want them to be workable as a show piece, although they are not meant to be your "go-to" calculator.

I need to learn more on the HP-41 peripheral systems to see if it is feasible to add them to the NP-41. Currently it does what Nonpareil does as the core engine is that. The MSP430FR6989 chip I used has 128K FRAM (program and volatile memory both uses it) and 2K SRAM.

The emulator size is around 26K right now, and I think I am emulating the 41CV w/ 336+176 registers. That takes up 532*14 bytes, or less than 8K, so there are potentially 80K+ FRAM memory for other use.

The currently design has a 9600 UART port which can talk to a PC via USB-Serial. The processor itself supports way more peripherals like SPI, I2C among others, So IR can be added, etc.

Right now I am working on the next PCB which would be display + MCU only (somewhat like DIY-4).