HP48 Clock Variableness

[TomC]

This is a very interesting thread.

I've long suspected that there is some inaccuracy induced by the OS- perhaps the interrupt structure:
1. A few quick tests I have done in the past show a loss of about 2 seconds per day - the equivalent of about a minute a month.

2. The clocks are always slow.

3. The 'measured' microprocessor clock speed is always 'slow' (relative to 4MHz), and varies (I suppose this could be a measurement issue in the diagnostic code)

Again, these are just suspicions/beliefs.

The bottom line is, after my testing, I'm hoping I'll come up with a CLKADJ constant for each machine.

Regarding the accuracy spec of crystals, I wonder how consistent the resonant frequency is - if it (let's say for instance) 1%, does this mean it is always 'wobbling' within 1% around the center frequency, or stays constant - at a constant freq within 1% of 32768Hz?

I may have (or may acquire) some high precision crystals.
There are other hardware ideas - swapping crystals in different hardware, etc...I could ramble on, but will stop for now.

Thank you all for your attention!

TomC