Sound Blaster Emulator for Dos?

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Re: Sound Blaster Emulator for Dos?

Postby gdjacobs » 2017-7-16 @ 02:42

The advantage of something like DOSBox with a new native core is that you don't have to completely re-engineer it if you run into compatibility issues. VDMsound is great, but NTVDM is a black box if you run into a corner case which doesn't work.
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Re: Sound Blaster Emulator for Dos?

Postby koverhbarc » 2017-7-16 @ 03:34

I wasn't proposing actually using NTVDM, since we have no source for it (the leaked source is for the wrong version, as I understand, anyway) and it requires Windows at a basic level. I was only using it as a comparison - as I already have - that might be familiar. Obviously we could do at least as much as that, if people put the effort into it. But those few that are willing and interested seem to have gravitated to DOSBox.
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Re: Sound Blaster Emulator for Dos?

Postby Jo22 » 2017-7-16 @ 03:46

@koverhbarc You're right, it would nolonger be DOS. It would be a modern OS compatible with the DOS ABI.
In the late 80s, such OSes existed. Namely PC-MOS, Wendin DOS, Real/32 and Multiuser DOS.
My point is, that there's little reason to create sound drivers which take up a significant amount of DOS memory.
I'd be more elegant to create an compatible system with the ability to run multiple copies of the command line interpreter.
Not serial, like DOS, but in parallel. Core devices, like VGA and audio could be emulated, while direct access to hardware would be retained.
An inferior example for this is the Win9x DOS window. This sure can be done better, if Windows is left out of the door.
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Re: Sound Blaster Emulator for Dos?

Postby gdjacobs » 2017-7-16 @ 06:30

I'm curious if DOSBox would be precluded from operating like this? I'm not familiar enough with the internals to know one way or another, although I suspect it has enough modularity built in to do the job.
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Re: Sound Blaster Emulator for Dos?

Postby mr_bigmouth_502 » 2017-7-16 @ 07:55

Stiletto wrote:
mr_bigmouth_502 wrote:A Soundblaster emulation with inbuilt FM synthesis would be like a holy grail for DOS, or even Win9x. It would make it so much easier to get a retro rig up and going since you wouldn't have to worry about ISA compatibility. Merely running DosBox on DOS would be interesting, but I'd be more interested in a soundcard emulator that could be used to run games natively.


There was a Win9x port of VDMSound. It worked in many cases. That'd at least help you on Win9x/Me.
http://www.vogons.org/viewtopic.php?f=17&t=900

I'm guessing it doesn't do FM synthesis though, or does it?
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Re: Sound Blaster Emulator for Dos?

Postby dr.zeissler » 2017-7-16 @ 09:35

Thx for that, I'll check this out too.
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Re: Sound Blaster Emulator for Dos?

Postby Jo22 » 2017-7-16 @ 15:44

FM synthesis doesn't require ISA DMA, just port writes. In theory, any bus should do.
Assumed that bus allows writing data to a given memory location ($388, for example).

But the idea is interesting. I wonder, since some people here already made AdLib and MPU clones,
would it be possible to create a new PCIe sound card ?

There are PCIe bridges (sample), and some of the other DOS sound standards were
less dependend on ISA DMA. WSS/GUS/PAS, maybe ?

The latter had an high-level API and could be implemented as a synthetic device.
Or somone people could create a new sound card type and write some DOS drivers for Miles Sound System, etc. ?
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Re: Sound Blaster Emulator for Dos?

Postby mrau » 2017-7-16 @ 15:54

sorry, i dont get how that bridge matters, if one is ready to write specific drivers then any sound chip will do, no?
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Re: Sound Blaster Emulator for Dos?

Postby Jo22 » 2017-7-16 @ 16:13

Uhm, a bridge makes it easier to port normal DIY ISA circuits to PCIe.
I imagine it would be fun to build your own sound card. :)
Besides, an OPLx PCIe card would be interesting and wouldn't require any drivers.

mrau wrote:sorry, i dont get how that bridge matters, if one is ready to write specific drivers then any sound chip will do, no?

If he/she is willing to write them for two dozen models, then that's fine.
But they are moving targets, I think. There will always be one person, who has a recent on-board chip that's no supported.
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Re: Sound Blaster Emulator for Dos?

Postby mrau » 2017-7-16 @ 18:03

so You would like to use an old sound chip with an isa interface with pcie? that sounds fun, there was this story that it was the direct interrupt line access that really makes think work like the old software expects.. how would You circumvent that? frankly i myself never understood why pci's way if informing of an interrupt was not good enough... imho having a dedicated well implemented bridge one could actually attach old isa cards to a new pc just like that?

regarding drivers - it is my understanding that for quite some time now only 2 standards matter - ac97 and HDA, for these open drivers exist already
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Re: Sound Blaster Emulator for Dos?

Postby Jo22 » 2017-7-16 @ 19:05

Hi, I agree to what you said. Attaching an existing ISA/PCI sound chip to a bridge isn't trivial and interrupts are sure causing some headaches.
I was rather thinking in smaller scales, like using FPGA or an ATMega chip to create a fictional sound card (playback only, mono or maybe stereo).
The bridge was only mentioned, because it allows us to use traditional homebrew parts, like 74 series address decoders and such.
If there was something like a PCI or PCIe development kit, we could *perhaps* skip that and create a sound card (or rather a simple DAC)
without the help of ISA technology..

Now that I think of it, a PCIe card with both an OPL2/3 compatible chip and an IRQ-less parallel port would be interesting.
If the port was hard-wired to port $278 and had some sort of Covox-style DAC attached to it, perhaps stereo-on-1 compatible,
most of the existing demoscene stuff and mod players would work, too. Real-Mode games could be supported by old SB emulators or Temu then.
It's not ideal, but would work with a decent number of games. Also, it would work around the issue with PnP LPT cards.
I know, it's not on par with a 192KHz 24Bit sound chip, but it would at least kinda work with modern i7 and i9 machines.

Perfect compatibility is perhaps out of reach, anyway, since also pure VGA support in modern GPUs is nolonger a selling feature,
but rather an afterthought. I assume, todays VGA implementation is similar to the synthetic VGA device which VirtualBox has got.
IMHO the last Windows that required VGA for installation was Windows 2K/Me. Windows XP is using 800x600 resolution, an SVGA/VBE mode.
So VBE3 support is maybe be still beeing cared of, since it is still required for installing Windows and since it is also beeing used by Linux.

mrau wrote:regarding drivers - it is my understanding that for quite some time now only 2 standards matter - ac97 and HDA, for these open drivers exist already

Hi, yes, I believe that's true. So far I thought these were specifications, though. Dunno if they (the chips) are compatible to each other.

Edit: Sorry for the bad wording. There are many typos, also. I really have to take some English lessons again.. :blush:
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Re: Sound Blaster Emulator for Dos?

Postby mrau » 2017-7-16 @ 20:15

so quite frankly, because graphics is the probably most important part of this, the virtual machine approach is still better than making up hardware, which i'll admit would be far more interesting than emulation;
maybe the generic driver code in dos could be improved a bit so it would cooperate better with the vm?
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Re: Sound Blaster Emulator for Dos?

Postby Jo22 » 2017-7-16 @ 20:46

I think so. From what I've seen, classic games like Commander Keen don't run that well on modern GPUs..
But I haven't checked FPS games! Some of them use VBE and may run OK or even benefit from VBE3 features.
In either case, it would be nice to have an emulated VGA as a fallback.

A VM -running on DOS or any other OS- could help with that. Maybe it is also possible to create some sort of
VM-Operating System (a hypervisor ?) for DOS. It would either boot before DOS, or could be launched afterwards.
Similar as to how EMM386 operates. With one or more V86 machines running a copy of DOS or Command.com.
Maybe also with its own drivers, so emulation of sound and graphics can be done transparently.
Whatever. The advantage would be, that normal DOS drivers and applications could still be used.
Sorry, that matter is not my special subject. But I know early multi-tasking DOSes had similar features,
so perhaps it can be done in such a fashion ?

Edit: Regarding the VGA thing.. I forgot to mention: My knowlegde about recent GPUs is quite behind the times.
It also has been several years (~08/09?) since I tried DOS games natively (which means in 16-Bit DOS) on a modern PC.
Unfortunately, I have no access to a modern PC at the moment (-> Athlon 64 user speaking).
So I can't re-check my former experience. But if there is some kind of "VGA compatibility test", please let me know.
Perhaps it would be a good idea to test modern graphics cards for bare metal VGA compatibility.
By modern, I'm thinking about something from this decade (2010 onwards).
I'm a proud err.. desperate user of a Geforce GF210, by the way. :(
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Re: Sound Blaster Emulator for Dos?

Postby Jorpho » 2017-7-17 @ 06:19

Jo22 wrote:I'd be more elegant to create an compatible system with the ability to run multiple copies of the command line interpreter.
Not serial, like DOS, but in parallel. Core devices, like VGA and audio could be emulated, while direct access to hardware would be retained.
An inferior example for this is the Win9x DOS window. This sure can be done better, if Windows is left out of the door.
Windows 95 went to exceptional lengths to accommodate DOS games written in all sorts of incorrect ways that did things to hardware and memory that they were not supposed to do. Any attempt to improve on this "inferior example" would encounter the same obstacles.

Jo22 wrote:But the idea is interesting. I wonder, since some people here already made AdLib and MPU clones,
would it be possible to create a new PCIe sound card ?
Like I said before, wouldn't any machine with a PCIe slot likely be much, much too fast for any DOS game to function properly?
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Re: Sound Blaster Emulator for Dos?

Postby koverhbarc » 2017-7-17 @ 11:39

As far as I know, there is no upper limit to CPU speed for properly-written DOS games, any more than there is for Windows games. Speed-sensitive games have already been a problem for a long time.

But a PCIe sound card seems a bit of a stretch. PC hardware just isn't normal hobbyist territory, except for simple interfaces like the serial and parallel ports which have disappeared by now.
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Re: Sound Blaster Emulator for Dos?

Postby keenmaster486 » 2017-7-17 @ 15:52

koverhbarc et al, I like where you're going.

I've wanted this damn "universal SB+FM emulator" since I was about 11 years old :lol: :lol: :lol:
I flermmed the plootash just like you asked.
Very silly indeed: https://audaxeundum.wordpress.com
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Re: Sound Blaster Emulator for Dos?

Postby Jo22 » 2017-7-18 @ 08:09

koverhbarc wrote:But a PCIe sound card seems a bit of a stretch. PC hardware just isn't normal hobbyist territory,
except for simple interfaces like the serial and parallel ports which have disappeared by now.

Uhm, hasn't this been done before (well, sort of) ?

From the ModPlay Pro what.new file:
"User definable output port for Mono and/or Stereo mode (for people with D/A's on a PC bus card)."

Making a Covox "sound card" should be feasible, at least.
It's essentially a bunch of 74 series chips and a resistor ladder.
For a basic model, we won't even require the interrupt or status lines.

http://retired.beyondlogic.org/spp/parallel.htm

The more complicated part is to figure how to connect it to PCIe (1x is fine).
A cheap PCIe-ISA bridge may or may not suffice for that purpose.
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