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Re: CVX-2 : covox adapter

Posted on 2017-12-04, 21:08

Yeah, but has anyone tested to see what the actual cut off for the frequency range for the R-2-R covox is? Can it actually output a 22.05 KHz frequency? The Covox has no filter at all (and the CVX4 also has a no-filter setting). So theoretically there is no cutoff. I think the easiest way to verify …

Re: AWE32/SB32/AWE64 SPDIF 18-bit output

Posted on 2017-12-01, 14:14

Am I correct that in order to get that HQ output you have to use a 24-bit software player with 24-bit sound card drivers? On the AWE32 PC, playing the music? No. Basically MIDI song says the EMU chip to play samples and it will do that and mix all together and that resulting mix is done within the …

Re: CVX-2 : covox adapter

Posted on 2017-11-29, 21:08

R2R ladder if you find suitable and affordable. We could make a solder kit. Would it be one of these? https://nl.mouser.com/ProductDetail/Bourns/4610X-R2R-104LF/?qs=sGAEpiMZZMvrmc6UYKmaNeW6aaSnYRiI1LIkquX0%2fPY%3d I think that would be good, except the minimum order is ten thousand because most …

Re: OPL2LPT

Posted on 2017-11-29, 11:44

But what if you make a sort of FIFO buffer? I am thinking of something similar to the Disney Sound Source: the data can come in at any rate, and it clocks it out at 7 kHz. If you were to build something like that, which can accept data at any rate (either from a COM or LPT port, wouldn't really …

Re: OPL2LPT

Posted on 2017-11-29, 07:11

Great product! Now for an LPT MPU / Midi interface for the MT32? ;) ?? LPT MIDI interfaces did exist, only need to clone one or design a new one. It will be easiest to modify SoftMPU to work with LPT connected UART/microcontroller. Full MPU emulation on a LPT dongle won't be necessary. Err... …

Re: x86 software vs hardware clocks

Posted on 2017-11-27, 12:44

in PC Emulation
Just looked at it(rotating the images 180 degrees to read the crystal values easier). The 25MHz crystals both say 25.175MHz. The 28MHz crystal seems odd indeed: VGA=28.3210MHz, PS/2=28.3220MHz Note that it reads 25.175000 and 28.322000, which do indicate it's designed for that (within tolerance) …

Re: x86 software vs hardware clocks

Posted on 2017-11-27, 11:27

in PC Emulation
Also, I've never found evidence that VGA clocks would be specifically tuned to NTSC based fractions, they were just standard crystals. The alternative (that VGA pixel clocks are unrelated to NTSC frequencies) implies that the VGA 480p signal being exactly 525 lines (exactly double standard NTSC) at …

Re: x86 software vs hardware clocks

Posted on 2017-11-27, 08:24

in PC Emulation
Then what about the VGA 25/28MHz clock? And the ET3K/ET4K clocks? Btw, anyone knows the exact EGA and MDA clocks? As well as the ET3/4K clocks? All I can find are rounded numbers, not exact values(e.g. like the VGA clocks already present in UniPCemu(25.2*1.001 and 28.35*1.001)?) EGA currently runs …

Re: x86 software vs hardware clocks

Posted on 2017-11-26, 22:15

in PC Emulation
There's also the problem of infinitely long numbers, like the (S)VGA frequencies? The same with MDA frequencies? I don't follow how are they infinitely long? Most later cards had a PLL anyway to generate target pixel clock with multipliers and divisors from commonly the 14.318MHz crystal onboard …

Re: x86 software vs hardware clocks

Posted on 2017-11-26, 00:31

in PC Emulation
I would not call it 14MHz clock, it would imply it is a 14.000MHz clock which is isn't. At least it should be called 14.318MHz clock. Good enough approximation for most use is 14.31818 MHz or 14318180 Hz. Actual definition for the clock rate comes from NTSC standards and is exactly 315/22 MHz. On a …

Re: OPL2LPT

Posted on 2017-11-25, 23:52

Hi all, Only thing is one pin is gnd (lm358) vs -ve (ca3240) power. No idea if it'll work! I thought it can't break anything anyway (opamp inputs/outputs and vcc are the same) until I can try and get the right part tomorrow, and would just give poor volume or sound quality? Ground is the negative …

Re: Reversing the Disney Sound Source

Posted on 2017-11-25, 19:01

The Noise coming from the NE555.. its exactly the 7,?khz Frequenz i can hear. And from the PS/2 Port from which i power it. Ohh, I get it now -- if you hear the sampling rate then that means you don't have a lowpass filter to properly reconstruct the DAC output. The bypass capacitor is integrated …

Re: Reversing the Disney Sound Source

Posted on 2017-11-22, 21:40

Now it works ;) its bit noisy because of the R2R Ladder. Some LPT Ports are really quiet, others let you listen to every hdd access :O But you have the FIFO chips between LPT port and DAC, so the noise must come from FIFO chips and how they are powered, but not from the LPT port. Having said that, …

Re: IBM VGA emulation

Posted on 2017-11-17, 16:52

in PC Emulation
Edit: Didn't we have part of this conversation before? https://www.vogons.org/viewtopic.php?f=9&t=52527 We did, but that was EGA, this is VGA. In CAPE I implement this as two separate pieces of code (mirroring two pieces of HW). Plus the BIOS and underlining HW is different enough. For example I …

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