Pragmatics of a polyphonic calculator (chapter 2)
02-06-2016, 07:57 PM (This post was last modified: 02-14-2016 01:33 AM by Joseph_21sv.)
Post: #1
 Joseph_21sv Member Posts: 89 Joined: Aug 2014
Pragmatics of a hypothetical polyphonic calculator
Ever since fully programmable monophonic sound came to handheld calculators in the form of the User RPL BEEP command with 12-digit floating point frequency control, there has been technical thought that it could be nice for a calculator to have polyphonic sound. After all, they all reasoned, it could only be logical that a polyphonic calculator should materialize. However, that failed to happen because no major manufacturer thought that that could be done profitably without crippling the calculator's numerical functionality very much. How correct that might ever have been is up for debate, but this is not the thread for that debate. Rather, it is a thread for discussing exactly what specifications a polyphonic calculator would need to have to be taken as at least a semi-amateur grade instrument.
Anyway, here is my list of minimum requirements for that standard:
CPU data bus/data register width: 8 bits
CPU base clock rate: 894.886 kHz
Hardware sound mixer (if used): Monaural Triphonic with at least one user-assignable voice
Display resolution: equivalent to 160x88
Display master palette: 8 colors (preferably 3-bit RGB)
Calculator type and level: Entry level Scientific/Business programmable
Floating point display precision: 10 digits
Programming model: partially merged keystroke
Program flow control: branching, conditional transfers
Storage memory on board: 64K
Do you agree that this, by post-HP 28C standards, makes a passable semi-amateur grade instrument?
Post: #2
 BarryMead Senior Member Posts: 416 Joined: Feb 2014
RE: Pragmatics of a hypothetical polyphonic calculator
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?
02-06-2016, 09:41 PM (This post was last modified: 11-15-2017 05:44 AM by Garth Wilson.)
Post: #3
 Garth Wilson Senior Member Posts: 490 Joined: Dec 2013
RE: Pragmatics of a hypothetical polyphonic calculator
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.

02-08-2016, 05:37 AM (This post was last modified: 02-15-2016 02:37 AM by Joseph_21sv.)
Post: #4
 Joseph_21sv Member Posts: 89 Joined: Aug 2014
RE: Pragmatics of a hypothetical polyphonic calculator
(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.
02-08-2016, 12:44 PM
Post: #5
 BarryMead Senior Member Posts: 416 Joined: Feb 2014
RE: Pragmatics of a hypothetical polyphonic calculator
02-08-2016, 01:06 PM
Post: #6
 Chris Chung Member Posts: 218 Joined: Aug 2014
RE: Pragmatics of a hypothetical polyphonic calculator
The required hardware to realize this is minimal. The requirement is quite similar to a project I did a few years back. Except that It was not a calculator. It got a decent size b&w LCD (from a nokia phone), simple polyphonic tone generation via s/w + pwm. Just add a keyboard and it can be a calculator.

It runs on the same 16bit MCU as the NP-25.

The schematic for this project is as below.

Code:
//               MSP430F20x2/3       ----------o--------------o Audio out //             -----------------     |         |              o  //         /|\|              XIN|-   |        ---             | //          | |                 |   .-.       --- 10-500nF    | //          --|RST          XOUT|-  | | 1-10K  |              | //            |                 |   |_|        |--------------- //      LED <-|P1.0             |    |        ___                                //            |                 |    |        ///    SD / MMC card      /|\ //            |    pwm out  P2.6|-----           ---------------------   | //            |                 |               |                Vcc 4|--- //            |    as CS    P1.7|-------------->|1 CS, select device  | //            |    as MOSI  P1.6|<--------------|7 MISO, data out     | //            |                 |   ----------->|2 MOSI, data in      | //            |                 |   | --------->|5 CLK, spi clock     | //            |                 |   | |         |                Gnd 3|--- //            |                 |   | |          ---------------------   | //            |                 |   | |                                 --- //            |                 |   | |           Nokia 5110 breadout   /// //            |                 |   | |   -----------------------------  //            |    as SCLK  P1.1|---|-o->|7 SCLK, spi clock            | //            |    as MISO  P1.2|---o--->|6 MOSI, data in              | //            |    as D/C   P1.3|------->|5 D/C, data or control       | //            |    as RST   P1.4|------->|4 RST, reset, low active     | //            |    as SCE   P1.5|------->|3 SCE, select , low active   | /|\ //            |                 |    ----|2 Gnd                        |  | //            |                 |    |   |                        Vcc 1|--- //                                  ---   ----------------------------- //                                  /// // //        SD (back side)                          Micro-SD (back side) //        __________________                      __________________ //       /  1 2 3 4 5 6 7 8 | 1. CS      .. SEL  /  1 2 3 4 5 6 7 8 | 1. NC             //       |9                 | 2. DATAIN  .. SDO  |                  | 2. CS      .. SEL //       |                  | 3. GND     .. Gnd  |                  | 3. DATAIN  .. SDO //       |  S O - + C   I   | 4. 3.3V    .. Vcc  |    S O + C - I   | 4. 3.3V    .. Vcc //       |                  | 5. CLK     .. Clk  |                  | 5. CLK     .. Clk //       |                  | 6. GND/NC  .. Gnd  |                  | 6. GND/NC //       |                  | 7. DATAOUT .. SDI  |                  | 7. DATAOUT .. SDI //       |                  | 8. DAT1            |                  | 8. DAT1 //       |                  | 9. DAT2            |                  | 9. DAT2
02-11-2016, 03:14 AM (This post was last modified: 03-04-2016 04:05 PM by Joseph_21sv.)
Post: #7
 Joseph_21sv Member Posts: 89 Joined: Aug 2014
RE: Pragmatics of a hypothetical polyphonic calculator
My bad, the calculator can get away with a graphic resolution equivalent to no less than 32x24 (I must have written off the Atari 8-bit family because it used a CPU little different than the Atari 2600 did) and a 16-bit CPU address bus width (in case the latter wasn't obvious from giving the base calculator 64K of on board memory).
Chris, speaking of the Nokia 5110, it looks to have been a very entry-level mobile phone and even entry-level mobile phones have supported polyphonic ringtones since the late 1990s, which is coincidentally the time polyphonic sound was predicted to come to handheld calculators (1979: monophonic sound output to audiocassette [Casio fx-501P], 1988: monophonic sound via internal speaker [HP-28C], ca. 1997: polyphonic sound via internal speaker [heaven knows which because never happened]). Since this calculator only needs to be an entry-level scientific or business calculator with a triphonic synthesizer, I suppose it can technically also get away with a monochrome display.
Of course, if you agree that these amendments to the minimum requirements for the calculator specifications are sound (pun for those willing to take it), you would still want more pixels or colors even so (there is very little that is really possible with only 96 bytes per frame unless you are clever with how you implement video interface logic).
03-07-2016, 05:56 PM
Post: #8
 Joseph_21sv Member Posts: 89 Joined: Aug 2014
Pragmatics of a polyphonic calculator (chapter 2)
At the bottom of the previous thread on this subject, I have proposed the following as the absolute minimum specifications needed for a polyphonic calculator to be viable as at least a quasi-amateur grade instrument, asking you if they still stand up:
CPU: 6502/M68xx, Z80/i8080 @ 894.886 kHz
Display: monochrome 32x24 dot matrix
Numerical functions and precision: Entry-level scientific/business-financial, 10 digits
Internal speaker
Sound decoder: Monaural Triphonic, 10-digit frequency precision
Programming model: merged keystroke with branching and conditional execution
On-board RAM: 64K
If they do, remember that this list of specifications is as minimal as possible and represents the least such a calculator can get away with and not all I or any one of you would want.[/code]
Post: #9
 BarryMead Senior Member Posts: 416 Joined: Feb 2014
RE: Pragmatics of a polyphonic calculator (chapter 2)
I can think of one other requirement that seems important for a polyphonic device.

The KEYBOARD LOGIC should allow for multiple simultaneous keys to be pressed at once if you intend to support chords. Typical row/column decoders do not allow for this so you may have to have one CPU I/O pin for each key if you want no limitations on key press combinations.

Hope this helps, Barry
03-07-2016, 11:08 PM
Post: #10
 Garth Wilson Senior Member Posts: 490 Joined: Dec 2013
RE: Pragmatics of a polyphonic calculator (chapter 2)
Quote:Typical row/column decoders do not allow for this so you may have to have one CPU I/O pin for each key if you want no limitations on key press combinations.

So you could go atypical and put a diode in series with each switch in the crosspoint matrix, so you can still scan 64 keys with 8 column output bits and 8 row input bits, and press any number of keys at once, unlike the situation with 2-key rollover. The output bits can also be used for other things between keyboard scans.

The other topic covered the other material.

03-08-2016, 06:49 PM
Post: #11
 Joseph_21sv Member Posts: 89 Joined: Aug 2014
RE: Pragmatics of a polyphonic calculator (chapter 2)
(03-07-2016 09:35 PM)BarryMead Wrote:  I can think of one other requirement that seems important for a polyphonic device.

The KEYBOARD LOGIC should allow for multiple simultaneous keys to be pressed at once if you intend to support chords. Typical row/column decoders do not allow for this so you may have to have one CPU I/O pin for each key if you want no limitations on key press combinations.

Hope this helps, Barry

That would be interesting to try. However, pragmatically, since the concept of this calculator is that it is to be handheld (e. g. a triphonic HP 38G) and handheld scientific and business-financial calculators, especially programmable ones, normally have fairly small keys so as to make room to dedicate keys to commonly-needed functions, it would then be too hard for people with low fine-motor skills to simply play a single line of melody on it. Moreover, since it is to be programmable, it is not even going to make sense to try to fix its synthesizer to any exact scale, although we could at least concede a pre-programmed frequency lookup table.
03-11-2016, 04:43 PM (This post was last modified: 03-14-2016 02:57 AM by Joseph_21sv.)
Post: #12
 Joseph_21sv Member Posts: 89 Joined: Aug 2014
Pragmatics of a polyphonic calculator (chapter 3)
At the bottom of the previous thread on this subject, I have proposed the following as the absolute minimum specifications needed for a polyphonic calculator to be viable as at least a quasi-amateur grade instrument, asking you if they still stand up:
CPU: 6502/M68xx, Z80/i8080 @ 894.886 kHz
Display: monochrome 32x24 dot matrix
Numerical functions and precision: Entry-level scientific/business-financial, 10 digits
Internal speaker
Sound generator: Analog Monaural Triphonic, no sampling/modulation hardware, 10-digit frequency precision
Firmware frequency lookup table
Programming model: merged keystroke with sound and graphics commands and subroutines, conditionals and for/while loops
On-board RAM: 64K
If they do, remember that this list of specifications is as minimal as possible and represents the least such a calculator can get away with and not all I or any one of you would want.
03-11-2016, 10:08 PM (This post was last modified: 03-12-2016 07:33 AM by Garth Wilson.)
Post: #13
 Garth Wilson Senior Member Posts: 490 Joined: Dec 2013
RE: Pragmatics of a polyphonic calculator (chapter 3)
There's no new material here. We've already been over this. I am interested in your project, but I would recommend keeping it all in one topic, unfragmented, so newcomers can more easily see where we've been, and to avoid cluttering the forum.

Edit: I see the moderators have combined the topics now.

My signature line has the HP-41 links portion of my website, but for this topic I should mention that most of the website is on the 6502 and related processors, methods in both hardware and software. I'm sure you'll find material there that's interesting, relevant, and helpful.

03-13-2016, 02:17 AM (This post was last modified: 03-13-2016 02:18 AM by Joseph_21sv.)
Post: #14
 Joseph_21sv Member Posts: 89 Joined: Aug 2014
RE: Pragmatics of a polyphonic calculator (chapter 2)
Is it OK with most of you that my list of minimum requirements assumes the calcuator side of the device to support either algebraic or RPN entry or should I have specified that verbally?
03-13-2016, 06:58 AM
Post: #15
 Garth Wilson Senior Member Posts: 490 Joined: Dec 2013
RE: Pragmatics of a polyphonic calculator (chapter 2)
(03-13-2016 02:17 AM)Joseph_21sv Wrote:  Is it OK with most of you that my list of minimum requirements assumes the calcuator side of the device to support either algebraic or RPN entry or should I have specified that verbally?

I'm sure most here, being on an HP forum, prefer RPN. I didn't start out in the RPN camp, but I've been there for the last 30 years now. If you want your little machine to do both (which you seem to be saying), go ahead. It sounds like two selectable calcs in the same package, having very little (if any) impact on the hardware cost, although there will be more software development time.

03-13-2016, 06:13 PM (This post was last modified: 03-14-2016 12:05 PM by Joseph_21sv.)
Post: #16
 Joseph_21sv Member Posts: 89 Joined: Aug 2014
RE: Pragmatics of a polyphonic calculator (chapter 2)
(03-13-2016 06:58 AM)Garth Wilson Wrote:
(03-13-2016 02:17 AM)Joseph_21sv Wrote:  Is it OK with most of you that my list of minimum requirements assumes the calcuator side of the device to support either algebraic or RPN entry or should I have specified that verbally?

I'm sure most here, being on an HP forum, prefer RPN. I didn't start out in the RPN camp, but I've been there for the last 30 years now. If you want your little machine to do both (which you seem to be saying), go ahead. It sounds like two selectable calcs in the same package, having very little (if any) impact on the hardware cost, although there will be more software development time.

I mean to say either one or the other of the two, I just wanted to do a sanity check of my "grocery list" of the least that would be accepted as "not just a glorified toy". Besides, it feels clumsy to me to have them implemented as opposed system-level operating modes on the same calculator because each uses a feature the other does not need (RPN does not need brackets, DAL/AOS does not need an external stack). That is, it would have been less clumsy for HP to implement the 20b/30b, for example, as separate Algebraic (with or "without" precedence) and 'Polish' (forward/reverse) models.
As for the "grocery list" itself, it is by no means to be taken as all anyone here desires because:
894.886 kHz is a fairly low clock frequency for a modern calculator
32x24 pixels is a very low resolution and monochrome is a very shallow color palette
This forum is mostly concerned with scientific and business-financial calculators which are not merely entry-level
Advanced programmers eventually discovered ways to make even a programmable interval timer simulate sample playback (MSX engineers have even made a plain AY-3-89xx PSG simulate CD-frequency PCM sample playback) and they even created AM synthesis effects collaterally when they did this simulation by certain techniques
03-15-2016, 08:52 PM (This post was last modified: 03-15-2016 08:55 PM by Garth Wilson.)
Post: #17
 Garth Wilson Senior Member Posts: 490 Joined: Dec 2013
RE: Pragmatics of a polyphonic calculator (chapter 2)
This topic is similar:

Note: The page linked there, https://www.teenageengineering.com/products/po, takes a long time to load, so be patient.

03-16-2016, 04:04 AM
Post: #18
 Joseph_21sv Member Posts: 89 Joined: Aug 2014
RE: Pragmatics of a polyphonic calculator (chapter 2)
(03-15-2016 08:52 PM)Garth Wilson Wrote:  This topic is similar:

Note: The page linked there, https://www.teenageengineering.com/products/po, takes a long time to load, so be patient.

The dot matrix display of the potential calcuator, though, will be programmable to do the a equivalent of everything the OP-1's is preprogrammed to do and more. Also, it will deliver fully preassembled with the batteries completely covered, as this other synthesizer of theirs does. Finally, it will have a synthesis engine up to the the quality of both of these.
03-18-2016, 04:43 AM (This post was last modified: 04-21-2016 03:37 AM by Joseph_21sv.)
Post: #19
 Joseph_21sv Member Posts: 89 Joined: Aug 2014
RE: Pragmatics of a polyphonic calculator (chapter 2)
I normally do not spam consecutive posts to threads, but I have to propose this to get the topic back on the rails:
The "least" any one of us might actually think needed in a polyphonic calculator is:
SoC: RISC CPU with 4KB RAM + 128KB Flash interfaced to Adobe RGB 64x32x3 gradient LCD driver + monaural sound codec with 10-digit frequency precision and MIDI
Internal speaker
Firmware melody voices: 3 (virtual square wave)
Firmware tracker and frequency lookup table
Numerical functions: HP-10/12C
Notation support: Algebraic only (with/"without" precedence) or Polish only (forward/reverse)
Programming model: HP-41C with graphics and sound commands
If this is acceptable, remember that it is intended to represent the least I or any one of you would let such a calculator actually get away with and not yet enough to be what any one of us would want
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