LPT DACs in stereo

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LPT DACs in stereo

Postby zbiggy » 2006-7-06 @ 11:53

Hi!

This patch is not finished yet. It is just the same as 'DAC on LPT1, covox emulation added' previous patch but with little fixes and first attempt to stereo implementation.

I finally understood how LPT stereo DACs autodetection works and since this patch dosbox tells DOS applications about Stereo-on-1 LPT DAC presence.

After running mp.com from mp219b.zip the stereo-on-1 output device is autoselected instead of SoundBlaster. Without this patch in dosbox the SoundBlaster is autoselected and Stereo-on-1 is greyed out/unavailable.

There is another kind of stereo on LPT which is also implemeted in this patch. However could not find any application with autodetection of this format the emulation should work.

Sound output is still in mono because could not find in documentation how to feed dosbox mixer with 8bit stereo data.
If anyone knows how AddSamples_s8 function works tell me.
Reading sources can lead to misinterpretation.
Google shows me only 1 link to 1 header file. Not too much...

I learned that all commercial games and commercial LPT DAC designes were pure mono.

LPT stereo design by hardware limitation just simply toggle signal to left or right dac from single mono 8bit output from LPT port using strobe signal lines.
Such design cuts sample rate by half to feed both DACs which reduces quality of signal.
Stereo DAC support was available only in module players and some demo productions. Such appliactions usually supports better sound outputs like GUS or SB so developing stereo LPT DAC support in dosbox has no sense. There are many better module players for current operating systems with much better sound rendering and hardware support so using oldies has no reason.

My patch at present adds raw LPT DAC support (known as covox or intersound MDO species) and autodetection support (described inside patch as 'stereo') which can improve current emulation in dosbox. I think that in this way the goal of dosbox to support DOS games is met without adding redundand mess. Autodetection will help in DOS games where there is no user config but everything is done internally before falling down to PC Speaker or No sound at all.

have a nice day,
Zbigniew 'zbiggy' Luszpinski
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Re: [patch] LPT DACs in stereo

Postby robertmo » 2006-7-14 @ 20:22

How does it exist together with Disney Sound Source? Normally only one device can be connected to LPT, so how game/dosbox know what to play disney or covox? Will a game detect both Disney and Covox available?
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Re: [patch] LPT DACs in stereo

Postby robertmo » 2006-12-24 @ 13:06

Has anyone been able to run Prince of Persia v1.0 with Covox?

I doesn't want to play for me with Covox neither in dosbox, nor with real 386 with real covox when a type:
prince covox

Some information on the different DOS versions of Prince of Persia.
(Press Ctrl-V during gameplay to find out which version you have).

Prince of Persia v1.0 : 1990
Original PC version; Has original color scheme (Level 3 dungeon is dark blue)
No Setup program; uses manual command line parameters:
j (joystick); vga, mcga, tga, ega, hga, herc, cga (graphics);
stdsnd, adlib, covox, gblast, ibmg, sblast, tandy (sound)
Cheat activation code is 'megahit'

Prince of Persia v1.3 : 1992
Same levels, but with new color scheme on some levels (Level 3 dungeon is dark green)
Complete Hardware configuration startup Setup program.
You can specify Graphics Mode, Input Device, Sound Device and Music Synthesizer.
Cheat activation code is 'improved'

Prince of Persia v1.4 : 1993 (from Prince of Persia CD Collection)
Levels and color scheme identical to v1.3 (Level 3 dungeon is dark green)
Limited choice for Hardware configuration startup Setup program.
You can only set Sound Device and Music Synthesizer (PC Speaker, Sound Blaster Pro, Other Drivers).
Cheat activation code is 'improved'
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Re: [patch] LPT DACs in stereo

Postby robertmo » 2006-12-24 @ 18:10

Unless of course covox parameter is for Covox Sound Master. I guess we won't know it without the possibility to check with a real card, or with original manual where it was explained. So has anyone got original manual for Prince of Persia 1 v.1.0? ;)
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Re: LPT DACs in stereo

Postby h-a-l-9000 » 2008-1-16 @ 16:06

I've worked on it for the two demos that don't like soundblaster.

Features:

- sample rate auto-detection
- mono/stereo auto-detection
- anti-click strategies
- data underflows less noticable

Apps:
Wish demo
Crystal Dreams demo
Crystal Dreams 2 demo
Lunatic demo
Modplay (all modes)
Shadow President
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Re: [patch] LPT DACs in stereo

Postby jmk » 2008-5-05 @ 16:15

robertmo wrote:Unless of course covox parameter is for Covox Sound Master. I guess we won't know it without the possibility to check with a real card, or with original manual where it was explained.

I may as well bump this old thread to mention that I've been looking into the Covox Sound Master and V1.0 of Prince Of Persia does indeed use it (the original card with the AY8930). Well, it does support practically every other PSG, so why not this one as well. :happyhappy:

As usual, there's some mysterious sample playing hardware in there that causes everything to get stuck, but the title screen will play until the point of the first (attempted) sample.
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Re: LPT DACs in stereo

Postby Great Hierophant » 2008-5-05 @ 22:46

Nothing concrete is really known about the Covox Sound Master 1.0 other than it used an AY8930 synthesis chip, two digital 9-pin gameports and it had some sort of DAC capability. The AY chip is a modest improvement of the famous '8910.
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Re: LPT DACs in stereo

Postby jmk » 2008-5-06 @ 12:49

The fact that there are a number of Covox cards does make things more confusing. :s-face:

(All numbers below assume a base address of 0220).

Some games support DAC at 022F (probably CSM+ and CSM II / Voice Master?).
Some games support DAC at 0222 (CSM?).

Finally, there seems to be a third method of playing samples, which I've yet to figure out (likes to make a horrible high-pitched noise over the AY though). The AY I/O registers (0E and 0F) are used for something...

According to one document I've read, CSM II and Voice Master use ports 0228-022F, but I can't find a thing on the older cards.

Mobygames bundles all Sound Master type cards in the one and a lot of games just say "supports Covox" to make the job a bit harder...

Here's a list of games (so far) that actually support the AY, although mostly in 8910 mode:
    Ultima 6
    Sim Earth
    Prince of Persia v1.0
    Spirit of Excalibur
    Vengeance of Excalibur

DAC list:
    Sim City - "3rd method".
    Big Business - 0222.
    Space 1899 - 0222.
    Prince of Persia v1.0 - "3rd method".
    Megatraveller 1 - 0222.
    Megatraveller 2 - (not sure).
    Alone in the Dark - 022F.
    Shadow of the Comet - 022F.
    Wizardry VII - (not sure).
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Re: LPT DACs in stereo

Postby WhosAsking » 2009-6-14 @ 18:45

jmk wrote:DAC list:
    Sim City - "3rd method".
    Big Business - 0222.
    Space 1899 - 0222.
    Prince of Persia v1.0 - "3rd method".
    Megatraveller 1 - 0222.
    Megatraveller 2 - (not sure).
    Alone in the Dark - 022F.
    Shadow of the Comet - 022F.
    Wizardry VII - (not sure).
I suspect this "3rd method" has to do with the original Covox Speech Thing (you know, the glorified LPT DAC). I recall that Sim City only supported the Speech Thing (and was the only thing supported--it predated the Sound Blaster, IIRC).
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Re: LPT DACs in stereo

Postby Great Hierophant » 2009-7-14 @ 05:51

WhosAsking wrote:
jmk wrote:DAC list:
    Sim City - "3rd method".
    Big Business - 0222.
    Space 1899 - 0222.
    Prince of Persia v1.0 - "3rd method".
    Megatraveller 1 - 0222.
    Megatraveller 2 - (not sure).
    Alone in the Dark - 022F.
    Shadow of the Comet - 022F.
    Wizardry VII - (not sure).
I suspect this "3rd method" has to do with the original Covox Speech Thing (you know, the glorified LPT DAC). I recall that Sim City only supported the Speech Thing (and was the only thing supported--it predated the Sound Blaster, IIRC).


Sim City also supports the Tandy DAC, at least in some versions.
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