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I notice Lotharek has released a Stereo POKEY board with 'U-Switch' (digital/analog logic switching adapter) built in, so enabling and disabling the second POKEY via the U1MB M0 signal is now possible without any additional hardware whatsoever.


While you're here ;):

Lotharek's not one to waste words, so just wanted to check if it is really sufficient to bridge/connect to each other the 1 and 2 pads on the U-switch and connect the BIN connector to M0 on the Ultimate1MB?

[attachment=637215:stereo.jpg]

I am so tardy in installing my upgrades that most have been superseded by improved stuff...

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Yeah: you can bridge those pins with a little sliver of wire, which I had to do on a 600XL where there was no room for pins/jumper. You can pick VCC and GND off the back of the second POKEY socket.

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You can pick VCC and GND off the back of the second POKEY socket.

Thanks. I thought Vcc and GND would come via the 6-pin header the U-switch is mounted on.

BTW: what is "SR"?

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Thanks. I thought Vcc and GND would come via the 6-pin header the U-switch is mounted on.


No: the 6-pin header optionally wires direct to a physical two-position switch whose behaviour is emulated by the U-Switch.

BTW: what is "SR"?


Now... I used to know this. Anyone?

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No: the 6-pin header optionally wires direct to a physical two-position switch whose behaviour is emulated by the U-Switch.
 

 

Ah, then I could actually use the channel selector to switch the stereo, if it's not too hard to connect to that. (I removed the RF modulator.)

 

I can't think of another use or is there any U1MB function that benefits from a hardware switch?

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If you already have U1MB in the machine, it makes no sense to use the channel switch instead of U-Switch. But in the absence of U1MB, the channel selector switch will work fine to turn stereo on and off. :)

Offhand, the only repurposed use I've made of the channel switch I can remember making is indeed turning stereo on and off on U1MB-less Ataris. I did originally use the channel selector switch in my heavily modified 1200XL to turn the internal PBI HDD adapter on and off, but I later added a second U-Switch so I could do that in software via an U1MB BIOS plugin. :)

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No: the 6-pin header optionally wires direct to a physical two-position switch whose behaviour is emulated by the U-Switch.


Now... I used to know this. Anyone?

Could "SR" be output for an internal speaker like the 400/800 have? Read something that it could be taken off a GTIA pin.

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BTW: what is "SR"?

 

"Sound right". You can attach a wire from this pad to pin 6 of the LM358 (the 8 pin chip near the RF modulator). This enables a feedback of the right channel to the standard (always mono) monitor output and RF modulator sound, too.

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SR is Serial Audio In (SIO)

 

Sure? The current version (Simple Stereo V2) hasn´t this pad anymore, the predecessor I´ve seen several times has SR as an output (see my post above). Maybe there´s more different versions out...

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"Sound right". You can attach a wire from this pad to pin 6 of the LM358 (the 8 pin chip near the RF modulator). This enables a feedback of the right channel to the standard (always mono) monitor output and RF modulator sound, too.

 

Oh, I always thought it was to mix-in Serial audio, just like Bell. But this sounds plausible, too :)

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Sure? The current version (Simple Stereo V2) hasn´t this pad anymore, the predecessor I´ve seen several times has SR as an output (see my post above). Maybe there´s more different versions out...

 

OK, so this would be useful for Stereo games that don't have a mono mode. Probably not a killer feature if it's no longer there in the new version. (I have yours too, tf_hh, but lean towards installing the old one in the 1200XL where I have pulled the RF modulator after converting it to PAL (figuring it would be useless anyway) and could use the RF switch to switch Stereo on or off.

 

One more thought: is there actually any good reason to turn stereo off, especially if you have the SR connected? Is there software that doesn't run with Stereo enabled or does it otherwise affect the system.

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One more thought: is there actually any good reason to turn stereo off, especially if you have the SR connected? Is there software that doesn't run with Stereo enabled or does it otherwise affect the system.

 

IIRC If stereo is enabled, all mono software can only be heard on the left channel.

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Simple Stereo came with two cinch connectors. As I plan to install a Sophia DVI as well, I will probably connect to a PC monitor. Most PC monitors with speakers and most PC speakers use a 3.5mm audio connector. AFAIK the difference would be common ground vs. individual ground for the cinch connectors. The 3.5mm connector would be much smaller and obviously need a single hole only.

 

Are there any other pros and cons to using a 3,5mm connector for stereo vs separate left/right cinch?

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One more thought: is there actually any good reason to turn stereo off, especially if you have the SR connected? Is there software that doesn't run with Stereo enabled or does it otherwise affect the system.

 

 

Atari800 emulator doesn't work correctly with Bounty Bob Strikes Back if Stereo is enabled, I don't know if that behaviour is the same on real hardware, it doesn't happen in Altirra. I've yet to find anything else that doesn't work with stereo installed and enabled.  

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Bounty Bob writes to one of pokey's mirror locations ($D210-$D2FF) and ends up on one of the mirrored stereo pokey locations. Might be that Altirra detects that and acts on it. I believe Phaeron was the one who found out why it didn't work.

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I checked it, and I remembered incorrectly. The BBSB issue was not a pokey thing, but VCOUNT. It uses $D47B instead of $D40B. It's mentioned in the Altirra Hardware Reference Manual.

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I'm seeing the same behavior in Atari800 and Altirra with stereo, but not all cart versions lock up.

 

The issue is that BBSB! uses $D25F (SKCTL mirror) to reset POKEY's random generator and then polls $D26A (RANDOM mirror) to wait for a specific value to appear. With stereo, this doesn't work reliably because the SKCTL write goes to the secondary POKEY and then the reads come from the main POKEY. The catch is that BBSB! runs as a diagnostic cart and no other POKEY init happens before this code, so this is actually relying on the power-up state of the shift register. If it has already been initialized by the U1MB/Incognito BIOS, or it's still at least partially initialized from the computer not being off long enough from the last time it was on, or the power-up state being good enough, then the random number generator will run and the check will pass. This means that on the real hardware, there are a whole bunch of reasons why this might or might not work with stereo.

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