I just saw Pyxis OS, as I see it can execute other apps that are stored on SD card.
Unfortunately this Pyxis OS require Arduino Mega, and I have only Arduino with ATMega328.
So my question is, Is there some library/OS that allows me to execute apps from SD (touch screen support is not required)
I have no idea how they can execute code from an SD card unless the have a boot loader that is designed to do that.
You could probably do something similar but it would not be easy.
Arduino ATmega chips can not directly (natively) execute ATmega machine language instructions from SD (or from anywhere else other than the Flash program memory built in to the ATmega).
What they call an "Operating System" is based on what they call a "Virtual CPU." Similar to an "Instruction Set Emulator" or "Interpreter," as we used to call them back in the 20th century, it reads "instructions" from the SD and executes code accordingly. The set of "instructions" in the SD is not actually ATmega binary machine language, but some special stuff created by a proprietary C compiler. (Not open source, but it's very inexpensive according to the web site.)
I am very interested in this.
Java should serve that purpose, but is not an option, java is very heavy (I know it has almost completely implemented a compiler that generated .class).
As colleagues told, the option is an interpreter.
One question guys.
They used Arduino Mega (ATmega1280) because the microcontroller is faster / more memory, or because somehow ATmega1280 allows memory hierarchy (execute instructions directly from SD)?