4-D (Sports) Boxing - No Tandy DAC

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4-D (Sports) Boxing - No Tandy DAC

Postby Great Hierophant » 2016-12-19 @ 22:46

4-D Boxing, also known as 4-D Sports Boxing in Europe, supports the Tandy DAC on top of the Tandy 3-voice music chip in those Tandy 1000 systems which have a Tandy DAC. DOSBox as of r4000 won't play back the digitized speech ("Fight!") and notes (percussion). I have linked to a file which gives a recording from my Tandy 1000 TL : http://www.mediafire.com/file/8z4jpz3mw ... oxing.flac The digital sound works with the Sound Blaster option.
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Re: 4-D (Sports) Boxing - No Tandy DAC

Postby NewRisingSun » 2016-12-20 @ 00:12

TD15.DRV uses direct DAC mode. DOSBox only supports DMA-driven mode.

Adding support would be as trivial as adding one line ("tandy.dac.chan->AddSamples_m8(1, &data);" below the "// direct output" comment), but then the sample rate will be whatever the game writes to ports C6 and C7, which unfortunately does not resemble the speed at which the game's Interrupt 8 handler actually writes bytes into the DAC. I tried and failed to understand how sblaster.cpp's command 10h (Direct DAC output on the Sound Blaster) detects the sample rate in a similar situation.
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Re: 4-D (Sports) Boxing - No Tandy DAC

Postby Great Hierophant » 2016-12-20 @ 04:07

Is there any difference then between the Direct DAC mode of the Tandy and the Sound Blaster versus a Covox Speech Thing or other non-Disney Sound Source parallel port DAC dongle?
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Re: 4-D (Sports) Boxing - No Tandy DAC

Postby NewRisingSun » 2016-12-20 @ 08:31

I think I figured it out now. At least it now produces samples in 4-D Boxing seemingly at the correct speed while not negatively affecting Sim City and Space Quest III v1.0P with its Tandy DAC driver. It does not sound as clean as your recording, but then again, your recording seems to be low-pass filtered anyway. As this is a patch against SVN r4000, it also includes my correction to low-frequency notes in Zak McKracken, which still has not been included into the main source.

Note that direct hardware access to the Tandy DAC was, and still is, disabled whenever the Sound Blaster is active. I have added a warning message to notify users of this. When direct hardware access to the Tandy DAC is disabled, Int1A-based accesses were, and still are, redirected to the Sound Blaster, which is why most people, including me, were not even aware of that limitation.

Edit: Direct hardware access to the Tandy DAC is now only disabled if the DAC actually does occupy the same port, IRQ or DMA. The original source did not bother to check whether they did, only if a Sound Blaster was active at all.
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Last edited by NewRisingSun on 2016-12-20 @ 11:34, edited 7 times in total.
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Re: 4-D (Sports) Boxing - No Tandy DAC

Postby NewRisingSun » 2016-12-20 @ 08:43

I have compiled a build of SVN r4000 with that source patch applied. And again, remember to disable the Sound Blaster via sbtype=none.

Edit: Direct hardware access to the Tandy DAC is now only disabled if the DAC actually does occupy the same port, IRQ or DMA. The original source did not bother to check whether they did, only if a Sound Blaster was active at all.
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Re: 4-D (Sports) Boxing - No Tandy DAC

Postby Great Hierophant » 2016-12-21 @ 04:50

Great job!

As far as a low pass filter goes, I did not consciously record with one. I simply connect the audio output from the Tandy to the line in on my PC' motherboard's sound hardware. My Audacity settings are pretty basic. I think any filtering is from the TL itself.

Speaking of patches overdue for SVN incorporation, I wonder if this Game Blaster patch here was ever included :
viewtopic.php?f=41&t=38350
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Re: 4-D (Sports) Boxing - No Tandy DAC

Postby NewRisingSun » 2016-12-21 @ 09:00

Don't be silly. ;)
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Re: 4-D (Sports) Boxing - No Tandy DAC

Postby DOSUserDude » 2016-12-21 @ 17:26

Great Hierophant wrote:Great job!

As far as a low pass filter goes, I did not consciously record with one. I simply connect the audio output from the Tandy to the line in on my PC' motherboard's sound hardware. My Audacity settings are pretty basic. I think any filtering is from the TL itself.

Speaking of patches overdue for SVN incorporation, I wonder if this Game Blaster patch here was ever included :
viewtopic.php?f=41&t=38350


DOSBox .75 will be released long before that happens...
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Re: 4-D (Sports) Boxing - No Tandy DAC

Postby NewRisingSun » 2017-1-04 @ 23:17

Aw crap, r4002 breaks this patch. :( Something funny going on in mixer.cpp in AddStretched...
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