Tuners

[Branimir]

Greets!

Is anyone familiar with the construction of pedal tuners that are out on the market (Korg DT10, Pitchblack, Boss TU2), do they all use the some circuitry/programmed chips or?

There is a silly reason why I'm asking this, and I found anywhere any facts about calibration of these devices.
Is it quartz controlled oscillator used in pedal tuners since most of the tuners have limited calibration range for A (437hz - 445hz for instance), but I guess since it's all digital, there's no need for quartz since there's AD conversion going on and then the algorythm picks up the string vibrating frequency on some sort of average, dunno and shows the results... Is there a way to "mod" the calibration? I need to tune, well I like to tune to 432hz for A and I use Boss TU15, and there's only like two pedal tuners that can calibrate into this territory - the Peterson and the Turbotuner, and there's that funny Rocktron tuner that can be calibrated via external input (note from piano, or guitar, etc)... So I'm guessing there's no technical reason for the rest of the market tuners to have limited calibration range... or?

Opinions, comments, appriciated!