newRPL: [UPDATED April 27-2017] Firmware for testing available for download

[Claudio L.]

(07-30-2016 06:24 AM)JDW Wrote:  Claudio, please forgive me if this has been asked before or is considered a silly question, but after a forum search I didn't find an answer, so here it goes.

Will newRPL improve battery life on the 50g?

Understandably, the 50g gets shorter battery life than legacy 4MHz and 2MHz (and below) Saturn processor calculators due to the high speed processor in the 50g. However, as we all very well know, most computers can reduce CPU speed at times when such is not needed so as to increase battery life. Is that possible in 50g hardware, and/or is there something that can be done in newRPL to ensure longer battery life versus stock RPL?

Thank you.

ARM processors all have programmable clocks, so you can vary the speed at will. The stock 50g uses the CPU at 12 MHz when idle (waiting for a key), and 75 MHz when you run any program (basically, whenever you see the hourglass it's running at 75 MHz).
newRPL does it slightly different:
* Runs at 6 MHz, instead of 12MHz. Because there's no emulator, 6 MHz is plenty for many tasks.
* Whenever it's idle waiting for a key, it actually stops the CPU altogether with a Wait-For-Interrupt.
* If you don't poll the keyboard for 300 ms (or I changed it to 500ms? can't remember), then it assumes it's running a program and goes at full blast 192 MHz. Whenever you see the hourglass in newRPL you are running at 192 MHz.
* As soon as your program ends and the calculator waits for a key again, the clock goes back to 6 MHz.

Basically, the difference is that because newRPL is so much faster than RPL, many programs will be able to run and finish within 500ms, even while running at only 6 MHz so it's less often that the CPU goes at full speed.
The stock firmware goes with the fastest clock as soon as the user presses the key, because the emulator itself needs to run at 75 MHz to emulate a Saturn at a decent speed (about 2.1x faster than the original when running at 75 MHz).