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MEtalGuy66

DUAL "POKEY" SOUND CHIP STEREO UPGRADE BOARDS

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I am trying to get enough people to finance a production run of this board:

gumby.jpg

 

This is an upgrade that is pretty common on the 8-bits.

 

It's been around since about 1991. Alot of people wire it themselves by soldering a second POKEY "Piggyback" on top of the existing one.

 

This board is designed so that you dont have to solder anything, you dont have to cut any traces, remove any components, or otherwise modify your motherboard at all.

 

You simply plug this board into your existing POKEY socket, drop two POKEY chips in the sockets on the board, and connect a single wire to pin 6 of your OS rom (or pin 13 of your CPU, whichever is easiest) to get the required A4 signal.

 

The board gives you header pins to connect external jacks for 2 separate audio outputs. One for each pokey chip. The original pokey chip also continues to work out of the factory atari audio out (via the monitor port or RF modulator.)

 

If you want, you can jumper the 2 signals together (by just placing a jumper across the header pins) and youll get the full output of both pokey chips out of the normal atari audio out. (eg. 8 voice mono instead of 4 voice stereo.) This does not change software compatability at all and is a good solution for those who dont want to drill and mount extra audio jacks in their machines, but would like ot hear the extra audio tracks in software that supports this upgrade.

 

 

 

Its 100% compatible with the current software that supports the "dual Pokey Stereo" (or "gumby" upgrade as some call it.)

 

heres a partial list of the known programs that support it:

 

- Alf-Demo by the Unknown Base (Netherlands);

- Alpha-Demo by GMG (Slovakia);

- AMS-Stereo player by ??? (author unknown), USA;

(there are at least two AMS-stereo-players, that let you play

*.AMS sounds in true stereo or at least simulated stereo!);

- ARS-Mori 16k Intro by Tristesse (music shortened and ripped from

Drunk Chessboard by Infinity!), Poland of course;

- Ballada sound by DJ V / BK (Poland);

- Base 33 by AIDS (msx by Greg, Poland);

- Chaos Music Composer version x.x patched by ??? , Poland;

(=> the original version by Janusz Pelc / LK Avalon is only mono,

but there is a patch available, as well as various patched CMC

versions on the internet; thus *.CMC sounds can be generated in

stereo!);

- (many) *.CMC sounds created by one of the many stereo-versions of

Chaos Music Composer;

- Cogito-Demo by AIDS (Poland)

- Do you see the light? sound-demo by Roemer of UNO (Germany);

- Draconus, patched version by ANG and/or Micro Discount (NL/UK)

(the original version by Zeppelin games is only mono!);

- Drunk Chessboard by Infinity (music by X-Ray!), Poland;

- Dynakillers (Game) by GMG, Slovakia;

- First of All (sound) by Raster, Czech Republic;

- Impossible but Real Demo by MacGyver (Poland);

- King of Aggregat by X-Ray / Slight (Poland);

- Megaplayer Versions 1.6 and 2.0 by MacGyver (Poland)

(=> and thus all *.CMC, *.MPT, *.TMC, etc. sounds played with

this sound-player tool can be heard in true or simulated stereo!);

- Multi-Pro-Tracker 2.4 (various versions) by Jaskier/Taquart?

(=> thus *.MPT sounds can be generated in stereo!), Poland;

- (many) *.MPT sounds created by the stereo-version of Multi Protracker;

- Nazebany by DJ V / BK (Poland);

- Overload sound by X-Ray / Slight (Poland);

- Raster Music Tracker 1.x by Raster, Radek Sterba (a PC program

that creates mono/4-channels or stereo/8-channels *.RMT sounds that

can be played back on the A8 or any Atari 800/XL/XE emulator);

- (most) *.RMT sounds created by Raster Music Tracker;

- Stereo-Patch for Pokey Player by ??? (author unknown)

(=> thus all Pokey-Player / *.V sounds can be heard in stereo!);

- Stereo-Patch for Softsynth by Freddy Offenga (Netherlands)

(=> thus Softsynth will create stereo-sounds!);

- Stereo Patch for World of Wonders by Freddy Offenga (Netherlands)

(World of Wonders is a great Softsynth sound-demo!);

- Still Alive (TMC-sound) by Greg, Poland;

- Time sound by X-Ray / Slight (Poland);

- Theta-Music-Composer version 1.x by Greg (Poland)

(=> thus *.TMC sounds can be generated in stereo!);

- (most) *.TMC sounds created by Theta Music Composer;

- Vanity sound by Kuchara / Excellent (Poland) ;

- Worms (320k-Demo) by Datri, Czech Republic;

- Zybex, patched version by ANG and/or Micro Discount (NL/UK)

(the original version by Zeppelin games is only mono!);

 

The price is gonna be $40.00US including shipping. This does not include POKEY chips.

 

This is a 100% tested professional PCB, with high quality components. I will stand behind this, and provide support for anyone who gets one.

 

This is totaly non profit. I am just trying to get enough people so that the friends I alredy know who want one can have one. If I can get at least 3 more orders, I can make a batch of boards. My time assembling and shipping them is free, and the cost to you is ENTIRELY PCB production, component cost, and shipping.

 

Anyone interested can PM me on here, or email: [email protected]

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That is exactly what I want to build. BTW do you mix the GTIA key click to both sound channels?

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That is exactly what I want to build. BTW do you mix the GTIA key click to both sound channels?

1021392[/snapback]

 

No It doesnt do that. But that an ineresting Idea.

 

Lemme look ito that and if it can be done on the hardware level, ill add that into the board design. If its a software thing, It'd be a simple matter of an OS patch.

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Will it work in a 1200XL??  The 1200XL will have a 32in1 OS in it with built in Basic.

1021450[/snapback]

 

It will work in any 8-bit ATARI that has enough room above the pokey chip for the board to physically fit without clearance problems.

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That is exactly what I want to build. BTW do you mix the GTIA key click to both sound channels?

1021392[/snapback]

 

No It doesnt do that. But that an ineresting Idea.

 

Lemme look ito that and if it can be done on the hardware level, ill add that into the board design. If its a software thing, It'd be a simple matter of an OS patch.

1021417[/snapback]

 

It is hardware level. Key clicks are generated in GTIA and mixed with POKEY output. I have not seen this mix in any stereo upgrade. And I am sometimes missing it. So I think it is good idea to mix the signal to both POKEYs outputs.

 

Also I think it is not the best to have raw output from POKEYs. Small stereo amplifier should be nice so you can have audio line out.

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That is exactly what I want to build. BTW do you mix the GTIA key click to both sound channels?

1021392[/snapback]

 

No It doesnt do that. But that an ineresting Idea.

 

Lemme look ito that and if it can be done on the hardware level, ill add that into the board design. If its a software thing, It'd be a simple matter of an OS patch.

1021417[/snapback]

 

It is hardware level. Key clicks are generated in GTIA and mixed with POKEY output. I have not seen this mix in any stereo upgrade. And I am sometimes missing it. So I think it is good idea to mix the signal to both POKEYs outputs.

 

Also I think it is not the best to have raw output from POKEYs. Small stereo amplifier should be nice so you can have audio line out.

1021479[/snapback]

I totally dont want extra analog audio circuitry in my machine. Im happy with nominal level audio out. I dont plan on driving any speakers or headphones directly off my atari. If I was building a laptop, I may consider this. But that is beyond the scope of what this upgrade is meant to do. When you start messing with analog circuits like pre-amps and stuff, you get into noise issues, etc. and to build a quality stereo preamp circuit would increase the board footprint, as well as the price, substantially.

 

If I was to do what you are talking about, Id build the stereo amplifier circuit as a a small separate board that mounts in the back of the machine, where ever you decide to put the actual output jacks. This way, its further away from anything that could cause noise on the input side of the amp, and just run shielded input lines over to the dual pokey board. This way, also, you could have more freedom to add additional inputs, or features to the circuit, without worrying so much about physical size.

 

The physical size of the pokey upgrade board is a key issue because we want one version that works (fits) in all machines.

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In fact, I already have a crcuit design for a small board that does just that. It has stereo outputs, both preamped, and nominal, and it has 3 sets of stereo inputs with trimmer pots to adjust the levels. I used it in an AMIGA 1200 TOWER system to mix the CDROM analog audio and the Delfina sound-card audio with the native AMIGA audio out.

 

It is relatively inexpesive to build on a piece of perfboard.

 

I can send you the specs on the circuit design if you are interested.

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That is exactly what I want to build. BTW do you mix the GTIA key click to both sound channels?

1021392[/snapback]

 

No It doesnt do that. But that an ineresting Idea.

 

Lemme look ito that and if it can be done on the hardware level, ill add that into the board design. If its a software thing, It'd be a simple matter of an OS patch.

1021417[/snapback]

 

It is hardware level. Key clicks are generated in GTIA and mixed with POKEY output. I have not seen this mix in any stereo upgrade. And I am sometimes missing it. So I think it is good idea to mix the signal to both POKEYs outputs.

 

Also I think it is not the best to have raw output from POKEYs. Small stereo amplifier should be nice so you can have audio line out.

1021479[/snapback]

I totally dont want extra analog audio circuitry in my machine. Im happy with nominal level audio out. I dont plan on driving any speakers or headphones directly off my atari. If I was building a laptop, I may consider this. But that is beyond the scope of what this upgrade is meant to do. When you start messing with analog circuits like pre-amps and stuff, you get into noise issues, etc. and to build a quality stereo preamp circuit would increase the board footprint, as well as the price, substantially.

 

If I was to do what you are talking about, Id build the stereo amplifier circuit as a a small separate board that mounts in the back of the machine, where ever you decide to put the actual output jacks. This way, its further away from anything that could cause noise on the input side of the amp, and just run shielded input lines over to the dual pokey board. This way, also, you could have more freedom to add additional inputs, or features to the circuit, without worrying so much about physical size.

 

The physical size of the pokey upgrade board is a key issue because we want one version that works (fits) in all machines.

1021556[/snapback]

 

There's no need IMHO for a pre-amp becuase you ae either going to PC self-amplified speakers, some entertaninment surround system or a regular stereo/surround amplifier. The sound will get amplified. Even if you just plug it into stereo inputs on a modern TV, it get's amplified some. If you aren't going to use at least ONE of these options, then why are you doing the upgrade?

Edited by Gunstar

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There's no need IMHO for a pre-amp becuase you ae either going to PC self-amplified speakers, some entertaninment surround system or a regular stereo/surround amplifier. The sound will get amplified. Even if you just plug it into stereo inputs on a modern TV, it get's amplified some. If you aren't going to use at least ONE of these options, then why are you doing the upgrade?

1021635[/snapback]

 

I don't know whether the POKEYs output a constant-impedance signal. If they do not, a preamp will be necessary to prevent distortion (one of the things I've noticed with my 7800 video mod is that for whatever reason its video output impedance is very inconsistent, so the wave shape changes totally based upon loading).

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There's no need IMHO for a pre-amp becuase you ae either going to PC self-amplified speakers, some entertaninment surround system or a regular stereo/surround amplifier. The sound will get amplified. Even if you just plug it into stereo inputs on a modern TV, it get's amplified some. If you aren't going to use at least ONE of these options, then why are you doing the upgrade?

1021635[/snapback]

 

I don't know whether the POKEYs output a constant-impedance signal. If they do not, a preamp will be necessary to prevent distortion (one of the things I've noticed with my 7800 video mod is that for whatever reason its video output impedance is very inconsistent, so the wave shape changes totally based upon loading).

1021641[/snapback]

Well, I can tell you that the signal level comming out of the board is quite useable, and plenty clear of distortion on my 130xe.

 

now. As far ast the GTIA keyclick thing:

 

If its a big issue for you that the keyclick come out of both stereo channels, you would need some sort of analog circuit to mix it with the second channel, independantly of the first. The signal (s3) comes from Pin 15 of the GTIA chip and (on the 130xe and 800xl) is mixed in with POKEY's audio, as well as the cartridge port ext. audio signal, and the SIO (cassete) audio, at pin 2 of U1.

 

 

You wanna know what would be kewl as hell.. If we built a separate board that plugged into the U1 socket, and:

 

a)mixed in all 5 signals appropriately.

b)provided stereo outputs with adjustable output level.

c)had adjustable high and lowpass filters.

d)stereo encoded the audio signal going into the RF modulator.

 

heheh.

 

Now THAT would be worth building.

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It is hardware level. Key clicks are generated in GTIA and mixed with POKEY output. I have not seen this mix in any stereo upgrade. And I am sometimes missing it. So I think it is good idea to mix the signal to both POKEYs outputs. 

 

Also I think it is not the best to have raw output from POKEYs. Small stereo amplifier should be nice so you can have audio line out.

1021479[/snapback]

 

Not to de-rail the thread, but does anyone know the reason that Atari did the keyclick in the 1st place? What I really find odd is the fact that because the clicks are generated via some WSYNCs, any code using DLIs gets disturbed by key presses. Seems like a dumb thing to do, considering how useful the DLIs are.

 

Stephen Anderson

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It is hardware level. Key clicks are generated in GTIA and mixed with POKEY output. I have not seen this mix in any stereo upgrade. And I am sometimes missing it. So I think it is good idea to mix the signal to both POKEYs outputs. 

 

Also I think it is not the best to have raw output from POKEYs. Small stereo amplifier should be nice so you can have audio line out.

1021479[/snapback]

 

Not to de-rail the thread, but does anyone know the reason that Atari did the keyclick in the 1st place? What I really find odd is the fact that because the clicks are generated via some WSYNCs, any code using DLIs gets disturbed by key presses. Seems like a dumb thing to do, considering how useful the DLIs are.

 

Stephen Anderson

1021714[/snapback]

I think the "keyclick" probably came about as an idea that originated on the 400. It had a membrane keyboard which was crap, unless you had some sort of positive feedback letting you know that you had pressed a key. I remember in the early 80s, the Timex/Sinclair machines also had a membrane keyboard, and one of the popular add-ons was a keyboard "beeper". This actually greatly increased typing efficiency because you KNEW when you had successfully tiggered a key input stroke.

 

As far as the use of the GTIA chip to produce these "klicks" (they sound more like a crappy 8-bit sample of a "wood-block" percussion instrument to me) I have no earthly idea why they decided to use this method, other than the fact that they didint want the keyclick to interrupt the atari's normal pokey audio. Who knows. But I've alwayse liked the keyclicks, personally.

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Ok.. Here it is...

 

 

ATTENTION:

 

FRIDAY IS THE DEADLINE FOR ORDERING THIS BOARD.

 

So if you want one, let me know by Friday, February 24.

 

I already have enough orders to make a production run of these boards

the question now is just how many. So after friday, I will submit the order to

the PCB manufacturer, and order the 74LS14 ICs from Mouser.

 

I would really like everyone who possibly can to go ahead any pay by Sunday, February 26. This way I can pay for the PCBs and the ICs.

 

I'll post another message to this effect on Friday, including Payment instructions via Paypal.

 

If I can place the orders by Monday, the 27th, I should have all the materials in hand by Thursday or Friday of next week, and assemble/test the boards over the weekend, and be ready to ship them out to you by Monday, March 6th.

 

Thanks in advance to all of you who have helped make this possible.

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Ok, I thought you guys might like to see what you are buying...

 

XS21.GIF

 

Any comments or suggestions are welcome.. After all, you guys are paying for this.. I'm in essence working for you...

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Ok.. Here it is...

 

 

ATTENTION:

 

FRIDAY IS THE DEADLINE FOR ORDERING THIS BOARD.

 

So if you want one, let me know by Friday, February 24.

 

I already have enough orders to make a production run of these boards

the question now is just how many. So after friday, I will submit the order to

the PCB manufacturer, and order the 74LS14 ICs from Mouser.

 

I would really like everyone who possibly can to go ahead any pay by Sunday, February 26.  This way I can pay for the PCBs and the ICs.

 

I'll post another message to this effect on Friday, including Payment instructions via Paypal.

 

If I can place the orders by Monday, the 27th, I should have all the materials in hand by Thursday or Friday of next week, and assemble/test the boards over the weekend, and be ready to ship them out to you by Monday, March 6th.

 

Thanks in advance to all of you who have helped make this possible.

1022216[/snapback]

 

 

Count me in for one!!

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Its also worth noting on the 'keyclick' that the Atari 800 had a seperate internal speaker that producing this sound which prob exlpains why the click sound is coming from the GTIA vs Pokey????

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Its also worth noting on the 'keyclick' that the Atari 800 had a seperate internal speaker that producing this sound which prob exlpains why the click sound is coming from the GTIA vs Pokey????

1022550[/snapback]

 

Yeah I am aware of that, and I guess that furthers the reasoning behind why the Pokey is not used to generate the keyclick. I still have no idea why they chose to use the GTIA (or prior CTIA in the 400/800 "Color Television Interface Adaptor") to generate sound of any kind.

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You have to remember that the GTIA is really a 2nd generation TIA (ala the Atari 2600). The TIA chip in the 2600 is both the video chip and the sound chip. It has what could be considered to be a crude 2-channel out-of-tune POKEY inside of it.

 

So from that angle, it's no big mystery that the GTIA has some vestigial sound capabilities.

 

Remember that the Atari 400/800 used an internal speaker for keyclick sound so that although POKEY scans the keyboard, the keyclick itself was originally routed differently from traditional audio.

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You have to remember that the GTIA is really a 2nd generation TIA (ala the Atari 2600).  The TIA chip in the 2600 is both the video chip and the sound chip.  It has what could be considered to be a crude 2-channel out-of-tune POKEY inside of it.

 

So from that angle, it's no big mystery that the GTIA has some vestigial sound capabilities.

 

Remember that the Atari 400/800 used an internal speaker for keyclick sound so that although POKEY scans the keyboard, the keyclick itself was originally routed differently from traditional audio.

1022693[/snapback]

 

Yeah good point. I never really thought of the 2600 as a predecessor to the 8-bit computer systems, but I guess technically, it could be considered somewhat so, especially when you consider the nature of the 5200 which was the 2600's direct successor. What's interesting as hell is that they went back towards the TIA type display architecture in the 7800. Id be willing to bet that the 5200 architecture was less cost effective, due to its home computer design origins. Maybe they realized that the 7800 type design, while more of a challenge to coders from a display tracking/manipulation standpoint (no ANTIC decoding bitmaps and "spoon feeding" the graphics chip,) could accomplish the same speed (for game purposes) and could be produced alot cheaper.

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I still have no idea why they chose to use the GTIA (or prior CTIA in the 400/800 "Color Television Interface Adaptor") to generate sound of any kind.

 

The real answer is probable this one (copied from a post on the "Console Keys" thread):

 

GTIA was designed to be the graphics output chip for both a game console and a computer device.

 

So it is basically the same reason why GTIA handles the Console keys and not pokey.

 

Also note that it is not used only for keyclicks. The "Buzz" sound also comes from GTIA/Internal speaker. The buzz/bell is perhaps, more important than the keyclicks.

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There's no need IMHO for a pre-amp becuase you ae either going to PC self-amplified speakers, some entertaninment surround system or a regular stereo/surround amplifier. The sound will get amplified. Even if you just plug it into stereo inputs on a modern TV, it get's amplified some. If you aren't going to use at least ONE of these options, then why are you doing the upgrade?

1021635[/snapback]

 

I don't know whether the POKEYs output a constant-impedance signal. If they do not, a preamp will be necessary to prevent distortion (one of the things I've noticed with my 7800 video mod is that for whatever reason its video output impedance is very inconsistent, so the wave shape changes totally based upon loading).

1021641[/snapback]

I KNOW from expoerience it works fine as I suggested. I have the upgrade in my XE and I have it hooked up to PC speakers and it works fine, very loud, no distortion, as is. Just like the one Pokey, standard, going to your TV through the RF modulator or out the audio line of the monitor jack to a monitor speaker, etc.

 

You do realize that the POKEY stereo upgrade has been around for like 15 years, right? It's been a "hack" by piggy-backing another Pokey on top of the first, he's just creating and easy-to-install board for the "masses." This is a LONG proven upgrade. That's why there are so many programs&demos out for it.

Edited by Gunstar

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So from that angle, it's no big mystery that the GTIA has some vestigial sound capabilities.

 

1022693[/snapback]

 

That's one thing I am not confirmed with.

So what are the sound capabilities of GTIA exactly. I mean, with TIA you can create music pieces and it is half a POKEY already.

Perhaps the GTIA would be interesting for FX generation while POKEY plays a tune?

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Atari realised their mistake using WSync in their keyclick routine. The XL/XE OS instead reads/compares VCOUNT to generate it's delay, making it unobtrusive to DLIs.

 

The GTIA CONSOL register is supposedly an I/O port. There aren't any data direction bits addressable, so it could be assumed that it's hardwired for 3 inputs, 1 output.

 

As for doing sound effects, check out Night Mission Pinball. It's one of very few games which use it.

 

Since POKEY can do forced volume to 16 levels (or more if you add extra voices), it's obviously the way to go since the GTIA only does 2 levels.

 

With some tricky programming, you could probably get some passable sound effects out of GTIA, but you would have very few cycles left over to do much else.

Edited by Rybags

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Atari realised their mistake using WSync in their keyclick routine.  The XL/XE OS instead reads/compares VCOUNT to generate it's delay, making it unobtrusive to DLIs.

 

The GTIA CONSOL register is supposedly an I/O port.  There aren't any data direction bits addressable, so it could be assumed that it's hardwired for 3 inputs, 1 output.

 

As for doing sound effects, check out Night Mission Pinball.  It's one of very few games which use it.

 

Since POKEY can do forced volume to 16 levels (or more if you add extra voices), it's obviously the way to go since the GTIA only does 2 levels.

 

With some tricky programming, you could probably get some passable sound effects out of GTIA, but you would have very few cycles left over to do much else.

1023001[/snapback]

 

 

Well... I never realized using GTIA as a sounddevice... But seeing POKEY reduced to two channels when doing IO, and the possibility of digitizing at the same time, it must be possible to play 3 voice tunes while disk I/O.

 

Or another aspect: Using triangles makes pokeys volume setting problematic. But with GTIA as FX/digi voice, you can play two full triangle voices and have a digitized FX/drum channel via GTIA ....

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