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Curt Vendel

Happy New Year... XM shipping this month

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I don't even think the YM is really necessary for this title, but obviously more options is always a good thing. I think an A8/5200 POKEY audio option would rock... then again, that goes for all of the 7800 titles that were available on the A8/5200/XEGS....

Listen to how good these YM samples are. http://atariage.com/forums/topic/174793-help-choose-my-next-sound-update/?do=findComment&comment=2173581

Dig Dug needs YM.

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More like 190 boards. Most fab houses will put all the TTL logic and other population like resistors, capacitors and other like components on for a song. It's not even worth putting them on yourself for the price you can get a machine to do it for you.

 

Usually, fab houses these days, only use pick & place machines, which is all SMD. I doubt they still have through hole machines, but what do I know.

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Usually, fab houses these days, only use pick & place machines, which is all SMD. I doubt they still have through hole machines, but what do I know.

 

Ya but that is worth it to change around some eagle files for I think you would agree.

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Ya but that is worth it to change around some eagle files for I think you would agree.

 

Depends on the user. :P But yeah, once the board works, I would change it to SMD and only place needed DIP parts myself.

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Depends on the user. :P But yeah, once the board works, I would change it to SMD and only place needed DIP parts myself.

 

That would save a ton of time and a ton of headaches.

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Is there a chance to know, that my order-confirmation was successful?

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If youve filled in the form at 7800xm.com with your current mailing info and whatever previous order information you had Ill do my best to make sure your XM pre-order ships

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I just purchased an "Atari 5200" with 12 games for it yesterday and a 600XL computer... Looks like I'm going to have to get myself an Atari 7800 system as well where as I sold my old one a couple of years ago. Can't wait to get my hands on the XM; I've been wanting to learn to program the 7800 for a long time.

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I just purchased an "Atari 5200" with 12 games for it yesterday and a 600XL computer... Looks like I'm going to have to get myself an Atari 7800 system as well where as I sold my old one a couple of years ago. Can't wait to get my hands on the XM; I've been wanting to learn to program the 7800 for a long time.

Why the quotes? Is it an exotic modded FrankenConsole? In any case, I’ve really warmed to the 7800 over the years, and homebrews make it worth owning irrespective of the XM.

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I think the 7800 is superior to the 5200.

The 5200 being a game console near exact to the Atari 8-bit Home Computer designed 5 years before Atari 7800.

Always opted for the 800XL or XEGS over the 5200 due to the fact that nearly every 5200 title is covered on the Home Computer, plus so many more games, software loaded from SIO devices from original Disk Drives to SIO Flash Card devices.

 

Atari 7800 is the evolution of the 2600 with a Sprite Engine, more RAM, and designed to have external hardware I/O (in cart, high score - which are finally realized with the XM's Pokey, Yamaha, High Score, etc. hardware).

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Why the quotes? Is it an exotic modded FrankenConsole? In any case, I’ve really warmed to the 7800 over the years, and homebrews make it worth owning irrespective of the XM.

 

You're right... Ever since the "Cuttle Cart" the 7800 has been an interest of mine for some time and I'm currently without one at the moment. I'll eventually get a 7800 at some point in time, possibly before the year is out. It's just when the XM ships, I'll most likely be getting much sooner than later.

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I think the 7800 is superior to the 5200.

 

In terms of graphics in my opinion... My only interest with the 5200 is learning to program using a Atari XL computer an possibly porting over to the 5200, but I've been wanting to make games for the 7800 for a while.

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FYI... Still tweaking on the Opamp section.... I get the pokey onboard all smooth, then the gain in the external pokey is off, I get them working together, then I loose the volume on the Yamaha, I get the Yamaha working but the gain sounds aweful.... so sorry about the long quiet period, just been going around a bit on this trying to get everyone playing nicely on the share audio line...

 

Taking a step back tonight, gonna clear off everything, move the DAC up to a breadboard and try to isolate things a little better, also I notice if I just combine Ch1 and Ch2 together into 1 connecting resistor the volume increases substantially.

 

If I didn't have so many 3012's I'd switch the the 3014's instead.

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When you compare games like Pac Man (Ms Pac Man) Centipede, Dig Dug and several others, the 7800 clearly has better graphics and with the pokey is toe to toe on par sound wise to the 5200/800... but the 7800 graphics are definitely better.

 

 

I think the 7800 is superior to the 5200.

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FYI... Still tweaking on the Opamp section.... I get the pokey onboard all smooth, then the gain in the external pokey is off, I get them working together, then I loose the volume on the Yamaha, I get the Yamaha working but the gain sounds aweful.... so sorry about the long quiet period, just been going around a bit on this trying to get everyone playing nicely on the share audio line...

 

Taking a step back tonight, gonna clear off everything, move the DAC up to a breadboard and try to isolate things a little better, also I notice if I just combine Ch1 and Ch2 together into 1 connecting resistor the volume increases substantially.

 

If I didn't have so many 3012's I'd switch the the 3014's instead.

 

Hi Curt :)

 

Sorry to hear you are still having problems with the XM audio. On my projects I switched from using op-amps to a simple NPN transistor mixing stage which actually works very well. As you can see when looking at the schematic below, I have several audio source options, including dual Pokey chips, and there is enough current to also drive into headphones if desired. Perhaps you can give a variation of my circuit a try to see if that helps.

 

Since you're not running stereo, the HCT4053 analog switches would not be required, and only a single transistor stage would be needed. The resistors feeding into the base of the transistor form the mixing and individual gain setting circuit. 100K input resistors set an appropriate gain for the Pokey audio output, which already has a high amplitude, whereas for more standard audio sources that produce a 1V p/p signal, 22K input resistors work well. If you have a stereo output that you wish to mix down to mono, simply use two matched resistors feeding into the common transistor base (one from the right channel and one from the left channel source). Be sure to include the series 0.1uf capacitors in order to not pass the DC aspect. See attached example circuit.

 

1088XLD Audio Circuit

 

post-42561-0-77366600-1553662203_thumb.png

 

Proposed XM Audio Test Circuit

 

post-42561-0-99772000-1553663461_thumb.png

 

I'm not sure how 'hot' the audio is coming out of the Yamaha DAC, so you might need to substitute a different resistor value in place of the 22K resistors. A higher resistance will make it quieter, and a lower value will make it louder.

 

This should be easy to breadboard, so just get in there and tweak the input resistors to get what you want. The value I show for Pokey should be good as is. Oh and I forgot you also have TIA's sound, so treat that the same as the Yamaha by mixing in those outputs as well (just add two more input resistors with series capacitors).

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I'm not sure what the point is of mixing the right and left channels of the Yamaha DAC when we can just code our music for mono. Even if there are existing stereo music files, they could easily be changed to output both channels to one channel of the DAC. It's just a setting in the Yamaha configuration registers. Let's simplify the hardware.

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Thanks guys,

 

I've got some trimmer pots coming in and some fresh breadboards, I've cleaned off the entire audio section and I'm going directly from the 3 test points I have and I've wired 3 lines from it along with Analog GND and +5v that'll go to the breadboard and I'm going to spend some time working this through. I agree with Perry.... instead of running both Ch1 & Ch2, what I found was the volume increased substantially from the DAC when I combined the two lines. I went down as low a 4.7k on the resistor and while volume was improved, the gain and distortion was too high.

 

Michael - did try your suggestion of the .1uf caps and I saw mixed results, but I haven't tried them in the scenario you propose... whats interesting if you essentially eliminating the opamp all together? Hmmmm... a 2222 Q? Okay, I'm game to try that, I don't think I have any of those in my parts box, so I'll get a couple sent in.

 

I'd really like to get this wrapped up, run a couple of boards with the final designs and the cut & straps implemented and populate, make sure everything is working good and get these off to the dev's so I can then rework all of the components from through hole to SMD and be ready to have the PCB factory run and populate the boards, then I can just add in the remaining items by hand.

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Atari 7800 is the evolution of the 2600 with a Sprite Engine, more RAM, and designed to have external hardware I/O (in cart, high score - which are finally realized with the XM's Pokey, Yamaha, High Score, etc. hardware).

 

The 7800's MARIA has just about nothing to do with TIA. The GITA is more accurately an evolution of the TIA.

 

Think of the 7800 as a completely new graphics engine that happens to contain 2600 hardware for backwards compatibility.

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The MARIA is more akin to how arcade games are done, there is no relation to the TIA and Drac is correct, the GTIA is the evolution of the TIA, both figuratively and literally.

 

 

 

The 7800's MARIA has just about nothing to do with TIA. The GITA is more accurately an evolution of the TIA.

Think of the 7800 as a completely new graphics engine that happens to contain 2600 hardware for backwards compatibility.

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2N3904's would also work in place of 2N2222 (PN2222 is the plastic equivalent that I use). The 2N3904 is a commonly used Atari part, so you might have that one on hand.

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Thanks Mike. I got in some 2222s and some variable resistors and some breadboards.

 

Spending tomorrow on the bench working the problem. Also Mark sent me a BIOS update to try out.

 

Just got tied up with work and things for the house. But tomorrow I have an open day finally to work on the XM

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