Pragmatics of a polyphonic calculator (chapter 2)

[Joseph_21sv]

(02-06-2016 09:20 PM)BarryMead Wrote:  Perhaps if you could share your VISION of how this instrument would be useful to an average user, we would be better able to evaluate how practical it would be to embark on a mission to bring this device into open-source development reality. How would such a device make YOUR life better? Are there any GENERAL PURPOSE uses for this device that vast numbers of users could get behind. What real world PROBLEMS would this device solve, and why to you think no-one has previously gone after these markets?

The vision of this device is that it will be the electronic parallel of a pocket harmonica, only more acceptable for real amateur musicians to use (Disclaimer: in no way to be taken to represent any opinion currently held or endorsed by poster). It would be a handheld device that I could use to make polyphonic music out of the box. Because its hardware can mix polyphonic sound, it could be recommended for music theory courses. One significant real world problem this device would solve is that people no longer seem to feel very enthusiastic about buying new touchscreen devices, at least not for the touchscreen part of them. For example, I am enthusiastic for the 128GB model of the current generation of iPod Touch because it is 128GB and I can then upgrade to a 128GB iPad rather than because it has a touchscreen. I know I have chosen a very general real world problem, but to say that this device would solve a real world problem which only applies to a particular market, even though that may well be true, would make it appear inapplicable to people who would otherwise actually want it.

(02-06-2016 09:41 PM)Garth Wilson Wrote:  Some projects are just for the fun of it. Why would anyone need a model railroad locomotive, especially a steam engine? But enthusiasts go to great expense to make operational ones, and they enjoy it immensely.

A users'-group contribution for the HP-71 in the 1980's was the LEX file NOISE which could make the beeper do a wide range of sounds, including music. Through HPIL, you could sync two or more together and have them play various voices of a piece of music, for polyphonic sound.

I don't see anything particularly wrong with your choice of specifications above; but why the arbitrary numbers? and why color? (Color is always a battery hog, because it cannot be reflective only. It requires that you continuously power a light source, unlike B&W. There goes the battery life. Written music is never in color anyway.) Note (haha) that there's no need for floating-point for this application (unless you really want it to be a calculator too). I have an article on scaled-integer and how it can be used very effectively in situations that most people think require floating-point. Note also that you can mix sounds digitally with simple addition before sending the result to a single D/A converter, so you don't need a hardware analog mixer. A hardware multiplier would be good though. I expect you'll want more memory though, or at least serial flash storage space.

FWIW, I would be able do what you're talking about with my home-made 65c02 workbench computer that I use as a Swiss army knife of the workbench for controlling processes, taking data, etc.. I also put a MIDI port on it, although I've never used that part for anything serious. (I'm a musician, cellist, and had visions of composing keyboard and orchestral music that beyond my ability to play, editing it, and playing it through my MIDI keyboard. I never did it, and now my interest is gone.) The piezoelectric beeper on the board definitely does not have music-worthy sound quality, but the D/A converter and output amplifier does; and if I use MIDI, then the sound is generated by the musical keyboard itself per the instructions from the computer.

The idea of this thread is the pragmatics of what would be the minimum needed for a polyphonic calculator project not to be seen as just for the fun of it, although it is fun, in a nerdy way, to entertain the thought of a polyphonic calculator existing. And it is convenient to be able to hold in one's hand the equivalent of a daisy chain of HP-71S with NOISE.LEX stored in ROM as well.
As to the numbers in the specifications, they are not arbitrary, but rather represent just about the weakest platform that should be taken as more than just a toy.
Here is where the numbers come from:
8-bit CPU data bus: The first music-worthy home computer systems were 8-bit
894.886 kHz: This was the CPU clock frequency of the NTSC version of the Intellivision
Triphonic sound: This is not a literal minimum, but would be just powerful enough to get through a beginning tonal music theory course
160x88 resolution display: This was the resolution of the Bally Astrocade in Basic Programming mode
3-bit RGB master palette: This was what the Atari Television Interface Adaptor could output to a color television through a SECAM decoder (it could output 8 shades of 13 or 16 colors through a PAL or NTSC decoder) although I have no idea why it was designed in such a way that it would output different color palettes to the television through different decoders
10 digit "floating" point display precision: Most business and scientific calculators have a display at least this precise
64K user memory on board: Home computers with polyphonic sound generally came off the shelf with no less than this much RAM
Color is not because it is necessary to have it simply to write music, but because home computers with polyphonic sound have always had full color display capability, which Demoscenes grew up around these home computers to take advantage of, and special mixing hardware is not out the question because hardware-mixed sound channels use minimal CPU power. By the way, "floating" point arithmetic on normal computers technically uses a fixed precision internally where the numbers are stored either as BCD or binary (e. g. HP Voyagers use 56-bit BCD numbers to do "floating" point arithmetic). Therefore, floating point merely exists as a convention for talking about how computers display the fractional numbers they operate on.