HP 48GX cpu clock speed

[TomC]

Cyrille:

Thank you - good information.

Is this clock available external to the processor? IE could we pipe in an external clock?
Or perhaps another method to control this clock external to the processor?

Regards,,
TomC

(02-27-2020 08:29 AM)cyrille de brébisson Wrote:  Hello,

The 48G chips uses an internal oscillator to generate the internal ~4mhz clock...
This oscillator is not tuned at the factory and, due to large variation in silicon wafers will be different from calculator to calculator. It will also change with temperatures as the physical characteristics of the oscillators component (resistors, NOT gates and capacitor) do vary with these...

Modern CPU uses PLL (Phase Locked Loop), which act as precise multiplicators of a precise cristal to set up clocks, but these are much more complex than a simple 2 NOT gate/1 resistor/1 cap system. Which is what the 48 uses.



Cyrille