[HN Gopher] Fourays: A Tribute to the AY-3-8910
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Fourays: A Tribute to the AY-3-8910
Sharing the introductory post for a chip-tune synthesizer I wish to
build.
Author : wdfx
Score : 43 points
Date : 2024-02-10 21:24 UTC (1 days ago)
(HTM) web link (doug.lon.dev)
(TXT) w3m dump (doug.lon.dev)
| exmadscientist wrote:
| FYI, that is _NOT_ what genuine Microchip DIP markings look like.
| Compare, for example, https://www.lcsc.com/product-detail/Analog-
| To-Digital-Conver... .
|
| Also there is zero chance that some of them have bottom-marked
| lot codes and some don't, given the same top date/facility code.
| Dead zero. And the cavity IDs on the DIP molds should be the same
| style, not randomly mismatched.... I'll stop here, but this is
| classic gray market remarking stuff. These are random old chips
| that have been relabelled.
|
| They may well still be AY-3-8910s in there -- the gray market is
| _very_ creative -- and may well be usable for you, but be
| cautious. If they look like they 're misbehaving, the chances are
| much higher than usual that it's not your fault.
| wdfx wrote:
| Yeah it's strange, they've clearly been relabeled and maybe
| only the top two I tested are real. Even if that is true I
| still have a couple of new toys to play with. I'll test the
| rest tomorrow.
| polpo wrote:
| I really don't understand why chip resellers re-mark chips like
| this. It's always obvious and it gives me the idea that they
| have something to hide. I've paid more for obviously used chips
| that I can tell are genuine than "new"/"refurbished" examples
| like the ones in this article.
|
| I love the AY-3-8910 and I've bought chips that were remarked
| in this fashion, fortunately they all worked ok and sound like
| the real deal.
| jacquesm wrote:
| There were such chips sold under the Microchip brand. I may
| still have one somewhere in a box.
| Eduard wrote:
| can you explain what "cavity IDs on the DIP molds" means?
| exmadscientist wrote:
| Things that are mass-produced in very high volumes by
| injection molding are never molded just one at a time: the
| molds have multiple cavities to make many parts at a time in
| a single molding shot. Very often, each cavity will have a
| marking to identify it: sometimes just a number, sometimes
| alphanumeric, sometimes dots. So you can tell that if
| everything coming out of cavity B12 is having quality
| problems, you probably need to inspect that cavity.
|
| Now take a look at the picture in the article of the
| undersides of the DIP-40 parts. There are two circles, which
| are either ejector pin locations or just things that look
| like them. (Ejector pins are the things that kick finished
| parts out of the mold once they're done.) Inside a few of
| those circles you find those cavity markings. I'm not sure
| exactly why the ejector pins and cavity markings (appear to?)
| coincide, but it's pretty common out there in the wild. You'd
| need someone who's more of a mold specialist and less of an
| EE to answer that one.
| jacquesm wrote:
| I've looked at Lego bricks more than I care for and I've
| noticed similar mismatches over the many years that a
| particular brick was produced, but they were all still
| original Lego. It could simply be that at some point a
| completely new mold was made and it has its markings in a
| different spot.
|
| There are also so called modular molds with interchangeable
| inserts.
| jacquesm wrote:
| What a fantastic project, I hope you get it all to work and it is
| definitely inspirational material.
| wdfx wrote:
| Thank you. I definitely intend to get this together, there's a
| lot of satisfaction to be had using a device you designed and
| built yourself.
| JKCalhoun wrote:
| Any YouTube videos of it making audio?
| wdfx wrote:
| I'm not quite at that stage, perhaps in the next couple of
| weeks and for the next article.
| nonrandomstring wrote:
| Amazing work. One random thought; Would giving each AY its own
| clock make stack/unison much richer?
| wdfx wrote:
| That hadn't really occurred to me actually. I'll keep it in
| mind as I start mixing multiple chips together.
| wdfx wrote:
| I am limited in the current design for clock sources but I
| intend to implement pitchbend so it'll be possible to detune
| two voices that would otherwise be sounding in unison.
| Dwedit wrote:
| I think the AY sound chip is overrated, nothing but pure 50%
| square waves. You move up to the next step, and you get the NES
| sound chip, with 12.5% and 25% duty cycles. Then you move up
| another step, and you have the Turbo Grafx sound chip, with short
| custom waveforms.
| karmakaze wrote:
| Looking at this list of sound chips[0] is an interesting tour
| through past encounters with computer and video-game systems.
| Even today music synthesizers are still trying to come up with
| new techniques for generation and filtering/modification.
|
| [0] https://en.wikipedia.org/wiki/List_of_sound_chips
| flohofwoe wrote:
| OTH it's impressive what you can do with multiple AYs when they
| have a dedicated CPU to drive them. For instance the Bomb Jack
| arcade machine has a separate sound board with 3x AY and a 3
| MHz Z80 CPU and it sounds pretty nice:
|
| https://www.youtube.com/watch?v=hCQ_iFsFQNA
| Flow wrote:
| Here's Jochen Hippel's(Mad Max in the Atari ST demoscene) use
| of the AY's on the Guryss hardware(x3 AY). It's a quite
| lovely tune. They use timers to make "buzzers" and "SID-
| sound".
|
| https://www.youtube.com/watch?v=K5TxsZNJpBA
| Dwedit wrote:
| Multiple AYs is a different story.
|
| You can approximate 12.5% and 25% duty cycle square waves by
| playing multiple tones at different octaves and a different
| volume level.
| wdfx wrote:
| For sure the 50% square wave is a limitation, but sometimes
| such limitations feed creativity. That's also why I intend to
| couple the oscillators to filters, so there's another dimension
| to play with.
| qiqitori wrote:
| The ZX Spectrum has this sound chip (or almost, for the pedants)
| and there's a lot of interesting music composed for it. Mostly
| from Eastern Europe apparently? Here's a good selection:
| https://zxart.ee/eng/music/top-100/
|
| (I had a bunch of time last year and learned a lot about some
| retro sound chips, including this one, and while at it converted
| two tunes I liked to MSX ROMs, as I have an MSX and the sound
| chip is the same: https://blog.qiqitori.com/2023/05/playing-psg-
| tunes-or-even-...)
| beagle3 wrote:
| This was the 128K spectrum. The original ones (16K and 48K) had
| a 1-bit CPU driven speaker, worse than the PC's original
| speaker (which could do background square waves thanks to a
| programmable timer).
|
| Even the 48K had interesting music, when programmers figured
| out how to do pwm with up to 5 channels. But not a lot of it.
| seu wrote:
| I love how well everything is explained and how clear he is
| regarding every step.
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