776 Reply by utz

(135 replies, posted in Sinclair)

A new breakthrough! Just implemented a low-pass filter. Check out the attached .tap - first pattern is without the filter, second with low-pass enabled.

The low-pass is implemented with this simple algo:

y[i] = a(x[i] - y[i-1])

where y is the actual output volume level, x is the unfiltered output, and a is a (time-related) constant, in this case 0.25. Using a = 0.125 gives better results, but I'd need to implement more volume levels to use it.

I tried implementing a high-pass, too, but so far no luck on that, because the algo for that can produce negative values (unlike the low-pass one where the result will always be >=0). The high-pass algo I have is

y[i] = a(y[i-1] + x[i] - x[i-1])

Any idea how to modify it so it'll always produce positive results? I could probably invert the output but that'd be too slow I think.

EDIT: Nevermind, got it. The current implementation is ugly as hell, but hey, it works wink

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777 Reply by utz

(2 replies, posted in Calculators & Pocket Computers)

Hellyeah, I'd love to be in a Metal band big_smile Maybe one day I'll drop by for a feature or something.

TI-89s are usually a bit easier to come by, though at this point I can't guarantee that qed68 will actually work on the 89. Also, I'm afraid the package isn't the most user-friendly, since it relies on GCC4TI/TIGCC, which is rather tricky to set up.

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778 Topic by utz

(2 replies, posted in Calculators & Pocket Computers)

Last year a kind soul donated his TI-92 Plus to me. A nice machine, with a 68k CPU running at 12 MHz, and of course a classic analogue IO port. Needless to say, something needed to be done, no matter how useless it would be considering hardly anybody owns this monster of a calc.

So lo and behold: QED68, a 4 channel PCM WAV module player running at around 24 KHz, with a total of 24 volume levels + overdrive. (And also my first forray into 68k territory).

demo tune
download (XM converter included)
source

The demo tune doesn't show off the sound quality that well, as I crunched the samples more than necessary (they're nominally at ~2750 Hz or so). The player will most likely also run on TI-89 and V200, but I can't verify this since I don't own these calcs.

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779 Reply by utz

(1 replies, posted in Calculators & Pocket Computers)

Uff... never tried this particular setup, so I don't really have a clue.
Perhaps you need a specific USB2Serial driver? People are using this one to drive their GrayLinks: http://www.prolific.com.tw/US/ShowProdu … mp;pcid=41

In any case  I've sent the TiLP developer a mail, maybe he has a solution.

UPDATE:

Lionel Debroux wrote:

The general rule is that such a setup cannot be made to work for the purposes of communicating with a TI calculator through the legacy I/O port, because AFAWCT, most USB / RS232 DB9 adapters don't provide the direct wire access that TI's custom half-duplex protocol needs.

At some point, someone mentioned that his PL2303-based adapter could do it, so I requested more information about it, and bought that particular
model. However, I never actually tested a known working BlackLink / $4 cable against it, so I can't point anyone to a precise model of an USB / RS232 DB9 adapter which I know works with them.

Nowadays, libticables provides a way to define the device corresponding to a cable handle, so that e.g. /dev/ttyUSB0 can be used instead of
/dev/ttyS0 on Linux. TILP doesn't provide an UI for the user to enter an alternate device, though, so users still have to resort to symlinks on Linux.

So, this doesn't sound very promising, unfortunately. You could still try the driver I linked above though, provided your adapter is PL2303 based.

UPDATE 2: Disregard my last statement.

Lionel Debroux wrote:

The GrayLink is a different matter. Unlike the BlackLink / $4 cable, it speaks a standard RS232 protocol, and performs two-way adaptation with TI's half-duplex protocol on the calculator side, without the computer being aware of TI's protocol.

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780 Reply by utz

(7 replies, posted in Other Platforms)

Ok, so most of you have probably all seen this elsewhere already:

https://www.youtube.com/watch?v=FVGYi-46G2s
http://irrlichtproject.de/downloads/dmg5th.gb

Good old pulse interleaving on the 2nd DMG channel while resuming normal operation on the other channels. Been meaning to do this for a long time, and it was also clear early on that this would have to be some sort of an April Fool's prank - so thanks for inspiring me, garvalf big_smile

So, lessons learned? Well, 1-bit sound is possible on the Gameboy. But, as Shiru mentioned, the Gameboy CPU is... eh... not exactly great to work with if you want to do something out of the ordinary. Not only does it miss more than half the Z80 registers, but also a lot of useful opcodes aren't implemented, and the ones that are there are almost always slower than on a regular Z80. HRAM is a nice feature but doesn't make up for the drawbacks. So the possibilities for 1-bit  on Gameboy are very limited. One could probably pull off a third 1-bit channel with a lot of fiddeling and loop unrolling, but overall I have to conclude that this platform really isn't worth it as far as 1-bit music is concerned.

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781 Reply by utz

(5 replies, posted in General Discussion)

@garvalf Apple II version is in TOSEC.

@matalog uhh... in this case it'll be difficult to find. There were quite a few monophonic pc speaker music "demos" back in the day, and this stuff isn't exactly well preserved online either. Really sorry man, I'll keep an eye out for this but I'm afraid I can't help you further at the moment.

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782 Reply by utz

(5 replies, posted in General Discussion)

Hi mate,
Sorry, I don't know this particular program. Was it monophonic, or did it do multi-channel music?
In any case, there is some old PC Speaker stuff here: http://cd.textfiles.com/psl/pslmonthly2 … /mus_spkr/
Also, Will Harvey's Music Construction Set had the Entertainer as a demo tune, you can probably find that on some abandonware site.

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783 Reply by utz

(16 replies, posted in Atari)

Hmm, perhaps you'd be interested in putting together a Huby-PF music disk release? I've got a few Huby tunes laying around in any case. What format do you need, z80 .asm or raw binary maybe?

Also I was wondering... how does the sound work on PF? Can you use timers, like on PC?

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784 Reply by utz

(7 replies, posted in Sinclair)

Agreed, for some engines the IO contention adds some very pleasant overtones/harmonics to the sound.

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785 Reply by utz

(10 replies, posted in Sinclair)

garvalf wrote:

There is indeed an RGB / VGA output (the white thing close to the ear output), but I don't know how to connect it to a vga screen.

That'd be a Molex connector, the kind of plug used to connect power to drives in PCs. Damn, they are really cutting some corners there.

I do understand the reasoning behind using a jack for audio now, though. As it's stereo, I assume they're actually emulating stereo AY output. And considering how packed the board is, they probably couldn't have fitted two RCA sockets.

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786 Reply by utz

(10 replies, posted in Sinclair)

Yeah, composite only is a downer, but I can kind of understand why. HDMI is not feasible for this kind of projects, because of the insane licensing fees (5000 USD per year + 1 USD per unit). VGA on the other hand is pretty much as outdated as composite, so they were probably thinking "why add another legacy port". But I agree, would have been nice-to-have.

Not using RCA for audio on the other hand is indeed a bad choice, didn't realize they use jack.

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787 Reply by utz

(7 replies, posted in Sinclair)

Sounds good to my ears wink Yeah, it's normal that it'll play a bit faster/cleaner on +2A, because that machine doesn't have that I/O contention issue.
Btw you probably know this already, but just in case - in Beepola, you can enable IO contention emulation in the options, then the sound will be closer to 48K/128K.

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788 Reply by utz

(10 replies, posted in Sinclair)

Whoops, that sold out quickly! Well, good for them. I think it's an excellent project at a very fair price, made by some very experienced people.

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789 Reply by utz

(16 replies, posted in Atari)

Wow, it sounds excellent! Well done, mate.
Can't help with porting Portfolio Manager, unfortunately - my PC programming skills are extremely limited.

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790 Reply by utz

(137 replies, posted in Sinclair)

It's probably just akward wording/translation, quite sure they mean regular beeper tunes.

On the other hand, if one wanted to take the rules literally, then a tune made with fluidcore/wtfx/qaop/etc would do the trick, since those are technically digi-engines big_smile

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791 Reply by utz

(16 replies, posted in Atari)

Youtube would be a good option, I think smile

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792 Reply by utz

(16 replies, posted in Atari)

Yes! So the day has finally come wink
Ummm... I don't have a Portfolio. Is there an emulator that can run this, and/or could you share a recording of the sound?

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793 Reply by utz

(166 replies, posted in Sinclair)

Ah yes, of course. I remember having to modify the .bmp, just could't figure out how anymore. So thanks for the reminder.

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794 Reply by utz

(9 replies, posted in Sinclair)

Well said, my friend. That's indeed one of the reasons I'm hooked on 1-bit music. There's a lot of uncharted territory waiting to be explored.

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795 Reply by utz

(137 replies, posted in Sinclair)

"digital modules" hehehehe I'll give them some digital modules big_smile Probably not though, got too much stuff to work on atm.

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796 Reply by utz

(166 replies, posted in Sinclair)

Perfect, this is exactly what I had hoped for. Thank you very much!

One little question, is it still possible to configure the color scheme? The current scheme isn't bad at all, but I like to work with a black background.

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797 Topic by utz

(2 replies, posted in Sinclair)

So them folks at Culturachip where having themselves a nice little 1-bit compo - without informing us, grrrrr! Anyway, some nice tunes were made, so check it out:

https://archive.org/details/VII_microco … achip_1bit

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798 Reply by utz

(9 replies, posted in Sinclair)

I see. So it makes sense that there is detune if the 0-delay is omitted - but that should be a self-detune, not a cross-detune, no?
Also, what do you think about "correcting" the other channel's counter when a pulse is triggered? I don't think it'd even need to be accurate, just decrement the counter by roughly ((pin delay length/undelayed sound loop length)+1) and if it overflows, jump right into pin pulse generation for the other channel (+ timer update as required), else skip the other channel update.

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799 Reply by utz

(166 replies, posted in Sinclair)

Excellent! I find the new block system very intuitive, and it will indeed help to speed up the (already fast) workflow.
Btw, how difficult would it be to display an automatically generated block list to the right of the screen (accessible with some hotkey, for faster navigation in the song)?

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800 Reply by utz

(9 replies, posted in Sinclair)

Hmm, I don't even understand why this doesn't cause massive cross-detune all the time.
That said, wouldn't it be possible to combine the pins after all, by adding up the delay values of both channels?

Edit: What exactly are the values that get fed into the variable delay? Is the delay for the 0-pulse some kind of inverse of the 1-pulse, ie the longer the 1-pulse delay, the shorter the 0-pulse one?

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