Re: Unpowered speakers/using PC speaker for audio

Posted on 2016-01-14, 13:38

by

by Scali

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I've had sound cards that only had one jack. That's exactly what I'm saying, is it not? Early sound cards had one output jack, which was multi-function (if they didn't have an ADC, such as the Adlib, the output was all they had). Even on most current onboard audio chips, there is one output ( …

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Re: Unpowered speakers/using PC speaker for audio

Posted on 2016-01-14, 13:32

by

by Scali

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

You are assuming all speakers and sound cards ever built complied with industry standards. That would be called a novice mistake On the contrary. It isn't exactly 'industry standard' to have a single output and (ab)use it for three different uses. They are 'bending the rules' somewhat, and made a …

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Re: Unpowered speakers/using PC speaker for audio

Posted on 2016-01-14, 13:16

by

by Scali

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

We are talking about a 386, back when many sound cards either had separate line out/speaker out or a jumper to use or bypass an amp. They did? In the 386 age, you mainly had Adlib, Sound Blasters and clones. The original Adlib only had a single jack. Sound Blasters had 2 or 3 jacks on the back: - …

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Re: Unpowered speakers/using PC speaker for audio

Posted on 2016-01-14, 11:54

by

by Scali

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Anyway, as per the link you provided, line out is meant to be a low impedance output driving a high impedance input. A 600ohm output driving a 10ohm speaker means that most of the power will be dissipated on the card itself, drastically reducing signal strength. If you are talking about a pure, …

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Re: Unpowered speakers/using PC speaker for audio

Posted on 2016-01-14, 09:43

by

by Scali

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

How exactly does a sound card -drive- its line- IN ? The sound card's output (which is usually designed as 'multi-function', so both for headphones and line-out) has to drive the line-in of an amp obviously (should have been obvious, since I also mentioned headphones, which also aren't part of the …

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Re: Unpowered speakers/using PC speaker for audio

Posted on 2016-01-14, 08:51

by

by Scali

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Not all of them. I've had some that couldn't be heard at all through unpowered speakers. As I say, that is physically impossible if they can drive a line-in or headphones. If you can't power speakers, then the output is broken, and you wouldn't be able to hear much via an amp or headphones either. …

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Re: How to make my PC speaker emulation support PCM audio?

Posted on 2016-01-14, 08:45

by

by Scali

in PC Emulation

in PC Emulation

Well, if your PIT emulation and downsampling work correctly, you should just get a regular PCM stream as output. I think you have to take it one step at a time... How about converting a .WAV file with PCM data to a 1.19 MHz PWM stream first, and then convert it back, to see if it works? You can make …

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Re: DOSBox-X notice: If microsoft pulls this stunt, I will be dropping Windows support

Posted on 2016-01-14, 08:31

by

by Scali

in DOSBox Development

in DOSBox Development

Microsoft now has an official support page documenting how you can block the Windows 10 upgrade: https://support.microsoft.com/en-us/kb/3080351 Doesn't look like MS wants to push Windows 10 to everyone.

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Re: Worst 90's computer brands?

Posted on 2016-01-14, 08:09

by

by Scali

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Ah yes, SiS... they produced some pretty dreadful chipsets back in the day. I'd also like to mention VIA. They refused to license technology from Intel, such as PCI, AGP, USB etc. So instead, VIA would try to reverse-engineer it themselves. The result was poor compatibility and often lousy …

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Re: Unpowered speakers/using PC speaker for audio

Posted on 2016-01-14, 08:03

by

by Scali

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Yes sound cards have amps but they aren't necessarily powerful enough to drive unpowered speakers. I would say they are. The output is either meant for line-level output or for headphones. Line-out level is more than enough to drive headphones or speakers directly. And unpowered speakers are …

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Re: Worst 90's computer brands?

Posted on 2016-01-13, 13:29

by

by Scali

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Quite ironic that IBM was so bad in the 90's when THEY designed the first x86 pc... Where exactly is the irony? The first IBM PC was a pretty horrible design as well. Compared to competing machines at the time, the IBM PC was way overpriced, and needed far more components than other machines. It …

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Re: How to make my PC speaker emulation support PCM audio?

Posted on 2016-01-13, 13:12

by

by Scali

in PC Emulation

in PC Emulation

One problem: If I would synchronize it at the framerate (60Hz or 70Hz depending on VGA screen resolution and pixel clock(25/28MHz clock)), it would only execute 60 blocks of instructions each second. So it would execute lots of instructions in 1/60th second, then wait. Since the PC speaker …

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Re: How to make my PC speaker emulation support PCM audio?

Posted on 2016-01-13, 11:31

by

by Scali

in PC Emulation

in PC Emulation

I'll make the 8086/8088 cycle accurate someday (but not for now). I think I will change the CPU to set its ticks passed to 1 tick per instruction for now and modify the speed correction routines to use the count of executed ticks and current running time to synchronize it's instructions 'cycle'- …

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Re: How to make my PC speaker emulation support PCM audio?

Posted on 2016-01-12, 08:05

by

by Scali

in PC Emulation

in PC Emulation

It doesn't make a difference if I process a loop calling tickPIT 1.19 million times per second or do it within the function itself? It will only generate more function overhead compared to the current method? (Function being called ~1190000 times a second) It does if you only record one PIT state …

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Re: How to make my PC speaker emulation support PCM audio?

Posted on 2016-01-11, 15:29

by

by Scali

in PC Emulation

in PC Emulation

Actually it's 3 states: one state for each channel (port 40 channel 0, 41 channel 1 and 42 channel 2). Yea, but that's what I mean. Only one state per counter per timespan. Read what I said again, in that context. I was only looking at a single counter, because it's the same problem for all …

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Re: How to make my PC speaker emulation support PCM audio?

Posted on 2016-01-11, 13:31

by

by Scali

in PC Emulation

in PC Emulation

I just took a quick look at your PIT code, but I'm not sure if I understand correctly. You seem to only record a single status for the PIT. So you have one status, and one reload point. That doesn't work if tickPIT() is not called often enough. Worst case, the PIT is set to a count of 1, which means …

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Re: 286 BIOS detecting 1.44Mb floppy drive as a 1.2Mb

Posted on 2016-01-11, 11:34

by

by Scali

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I don't think there *is* a way to autodetect what type of floppy drive is connected (you can detect if a drive is present or not, but that's it). I've not seen it on any of my systems, and I wouldn't know how the floppy interface would even make it physically possible to detect. IDE is different, …

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Re: 286 BIOS detecting 1.44Mb floppy drive as a 1.2Mb

Posted on 2016-01-11, 08:10

by

by Scali

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I wonder... on an AT the configuration is just stored in the CMOS memory of the MC146818 chip. See here: http://bochs.sourceforge.net/techspec/CMOS-reference.txt So I wonder what happens if you were to manually poke the right values in there from BASIC or debug. Since it is CMOS memory, the values …

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Re: 286 BIOS detecting 1.44Mb floppy drive as a 1.2Mb

Posted on 2016-01-10, 18:02

by

by Scali

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Is that a thing on I/O cards, jumpers setting the drive type? Well, I'm not sure. I've seen some XT-clones with jumpers to set the drive configuration on the motherboard (IO was integrated on the board). 286 systems tend to have CMOS configuration for this stuff, but perhaps you have some kind of …

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Re: So what do you guys do... you know, in real life?

Posted on 2016-01-09, 20:13

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by Scali

in Milliways

in Milliways

I'm not a software engineer, but I play one on TV.

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