New firmware for the Swissmicros DM15L

[jebedeo]

Although I love my DM15L I couldn't help but notice that its modern matrix LCD has plenty of room to display two lines and a lot more digits, so I thought it'd be fun to write my own firmware and implement some of the things I wish the DM15L had. I use this calculator with my firmware on a daily basis (IC engineer) for quick calculations and that reflects what is implemented here and what isn't. I would love to hear from people whether they're interested at all, and get some feedback as I implement the rest of the functionalities.

* What is this firmware for?

- Swissmicros DM15L owners that want to try a more modern firmware.
- I only have the DM15L calculator so it's only tested on this platform. Might work on the DM15 too.

* What's implemented?

- Two lines to look at X and Y registers in all their glory
- All single key functions like square root, logs, trig functions, et cetera.
- Store and Recall operation with support for + - * / operations (like on the HP42s)
- FIX/SCI/ENG formats
- Statistic functions and registers R2 through R7

* What's missing?

- No complex numbers
- No matrix support
- No programmability
- No integration
- No solver

* How do I get set up?

- Download the attached file LF15L_beta230604.txt
- Follow the usual steps to update the firmware for you DM15L (https://technical.swissmicros.com/voyage...are_update)
- TLDR: from linux, something like $ lpc21isp LF15L_beta230604.txt /dev/ttyUSB0 115200 12000