Question: history of HP 41c tones

[Gene]

Does anyone know the thought process behind the HP 41 team's choice of the built-in tone frequencies? It has often seemed so odd to me.

Why not choose frequencies that were actual musical note frequencies for a bit more than an octave? Is the bender not able to drive those? Seems as if that would have made using them much "easier" for music.

Any ideas ?

[Ángel Martin]

(02-18-2015 01:09 PM)Gene Wrote:  Does anyone know the thought process behind the HP 41 team's choice of the built-in tone frequencies? It has often seemed so odd to me.

Why not choose frequencies that were actual musical note frequencies for a bit more than an octave? Is the bender not able to drive those? Seems as if that would have made using them much "easier" for music.

Any ideas ?

FWIW, there are a few MCODE functions in the SVROM to play the musical note frquencies "DO, RE, MI, FA, SOL, LA, SI" (i.e. french for C - D- E- F- G- A- B-).
As to why they chose those TONES, my non-informed guess is they were easier to implement?

[Massimo Gnerucci]

(02-18-2015 02:16 PM)Ángel Martin Wrote:  the musical note frquencies "DO, RE, MI, FA, SOL, LA, SI" (i.e. french for C - D- E- F- G- A- B-).

...and italian, too. :)

[d b]

One saturday back in '86 I assigned the ten notes on the PPC rom to wrap around the right side of my 41 and took it over to my bud Jordan's place. I thought it would impress him, being a piano player and all. He touched all the keys once, thought a bit, and busted out with a rousing version of “Mary Had A Little Lamb”. I turned out to be the impressed one. He told me that he'd have to think of a better song for it because it sort-of approximated three notes per octave like Chinese classical. Jordan sure knew a lot. The PPC ROM "telephone book" didn't even say that.

[Monte Dalrymple]

The biggest problem is the fact that the high or low time of the signal driving the piezo element has to be a multiple of the instruction cycle time. This cycle time is nominally 155.6uS. So, for example TONE 9 has a three-instruction low and high time, giving a frequency of 1071Hz. TONE 8 has a four-instruction low and high time, giving a frequency of 803Hz. TONE 7 has a five-instruction low and high time, giving a frequency of 643Hz. These tones are individually coded. The remainder of the tones use a common routine to save code space. This common routine is 6+n instruction time long (for each phase of the piezo drive). And n is set by the TONE number as follows: TONE 6 has n=2, TONE 5 has n=4, and so on, down to TONE 0 with n=14. So, you could get better control at the low end of the frequency range, but it would take more code space. I guess that what they came up with was a reasonable compromise.

For 41CL users, try loading YFNX and then executing "41CL" Is what I was trying to do recognizable?

Monte