On my Tandy 1000 HX (GW-Basic v2.02) using SOUND OFF will still play the sound. I have to use BEEP OFF in order to disable the sound from playing. Internal speaker tested. 😉

Could you do one more test for me, just to be clear. Please open GW-BASIC, and run the following program:

10 BEEP OFF: SOUND ON
20 BEEP
30 SOUND 500, 30, 15, 0
40 NOISE 0, 15, 30
50 PLAY "C D E F"

When you run this without an external speaker attached, do any of the statements play audio, or do you just get silence for all four?

Thanks for the help Chilly Willy. You must be frozen through-and-through! 😁

SOUND OFF or ON has no effect on my Tandy. SOUND and PLAY functions will always play until, BEEP OFF. NOISE gives me an "Illegal function call". I'm not sure why. Looking into it now.

I see now. If I use SOUND OFF, the NOISE function throws an illegal call. So... SOUND OFF only seems to effect the NOISE function and BEEP OFF effects SOUND and PLAY functions. Which is weird. You would think SOUND OFF wouldn't play SOUND 500, 30, 15, 0. Interesting...

For some reason, the designers labeled the commands weirdly. SOUND ON/OFF toggles audio going to the RCA jack (external speaker), while BEEP ON/OFF toggles audio being played on the internal speaker.

According to the manual, NOISE is set to only work on the external speaker, it purposely throws an error if SOUND is set to OFF. I'm not sure why, but the manual suggests that it uses the TV or monitor's built-in speaker to produce the noise, so I wonder if the first models lacked the ability to play noise on their internal speakers?

So, if you run this line: "BEEP ON : SOUND ON : NOISE 0, 15, 30" do you hear noise from the internal speaker?

Yes. On a Tandy 1000 HX, it only has the internal speaker. No external speaker option except for a headphones jack.

You might find this article on GH's blog interesting: http://nerdlypleasures.blogspot.com/2013/06/i … 1000-sound.html
There appears to be some lack of consistency between models.

Since this topic is in regard to DOSBox, at least initially, I should point out that DOSBox does not implement multiplexer bits on port 61h, and the related BIOS function (INT 1Ah/80h) does nothing but fake success.

Chilly Willy: Thank you very much for helping me. I've been trying to get a more detailed explanation of the audio capabilities of BASIC on the PCjr and Tandy 1000 for the Video Game Music Preservation. Here is my current attempt: http://www.vgmpf.com/Wiki/index.php?title=Tandy_BASIC_MML

ripsaw8080: Thank you for that link, that clears up a lot of my questions about the oddly-named BEEP OFF and SOUND OFF features. This also confirms my suspicion that DOSBox currently does not accurately emulate toggling the speakers on and off for the Tandy or PCjr and explains why the behavior of BASIC in DOSBox was acting contrary to the Tandy manual.

I'm thankful that DOSBox focuses is on playing games rather than mere accuracy, and I doubt speaker toggling will ever have a detrimental affect on a published game, so, no need to address this.

Does DOSBox keep track of known inconsistencies that won't/shouldn't be addressed? If not, I'd like to help create one. I think it would be useful to direct people to it when they ask about why a particular feature doesn't behave as expected.

No problem. 😉

Thanks for writing that up. Specially when you have quirky things like BEEP and SOUND in GW-Basic, all because of how a Tandy was built. It's nice to have a better understanding of how and why it works the way it does.