Re: why sb emulation require virtual 86 mode

Posted on 2021-01-18, 21:22

by

by Benedikt

in Marvin \ Sound

in Marvin \ Sound

The bottom line is that you need some form of virtualization or code patching. Virtualization can be hardware-assisted as in Virtual 8086 mode, which emulates real mode, or as provided by VT-x and AMD-V which go far beyond that but require a much more recent CPU. The dedicated interception …

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Re: VESA mode programming from real mode

Posted on 2021-01-18, 15:14

by

by Benedikt

in Marvin \ Software

in Marvin \ Software

If you are going to use some sort of PutPixel function, buffer the current bank number somewhere and check whether you really have to update it. A PutPixel function that explicitly sets the bank via VBE call every time is abysmally slow.

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Re: Getting CGA Stable on Composite Monitor

Posted on 2021-01-18, 14:16

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

Potential modifications: If your JVC monitor uses a TDA4510 as PAL decoder, you could convert it to NTSC by replacing the TDA4510 and its support circuitry with a TDA4570 NTSC decoder and its support circuitry. JVC is a Japanese brand (NTSC territory), so a sufficiently flexible PCB design would not …

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Re: SID LPT (and maybe SSI 2001 LPT.. :-) )

Posted on 2021-01-18, 12:45

by

by Benedikt

in Marvin \ Sound

in Marvin \ Sound

There will certainly be opportunities for future collaboration on the software side.

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Re: Getting CGA Stable on Composite Monitor

Posted on 2021-01-17, 15:36

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

The ATI Graphics Solution in your picture is definitely not going to output a PAL signal via its composite port. It's either NTSC or black and white, both usually with 60Hz. However, you could write a TSR driver that intercepts video BIOS calls and sets the CRTC registers to values that result in …

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Re: MUS-2020 Prototype - Creative Game Blaster Clone

Posted on 2021-01-13, 21:39

by

by Benedikt

in Marvin \ Sound

in Marvin \ Sound

While we're at it, you could also add a few keep-out areas for the copper pours and try to keep the different parts of the ground plane connected in as many places as possible to avoid unwanted antennas.

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Re: Newly written driver(s) for Sierra's Creative Interpreter – Starting with Plantronics ColorPlus

Posted on 2021-01-13, 21:23

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

Your changes mostly relate to the memory offset calculations for the scan lines, right? I think that the fastest and most portable technique would use another lookup table, but I'm not entirely sure.

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Re: GLX Player the only XT player ? Check Mod Master...

Posted on 2021-01-08, 10:42

by

by Benedikt

in Marvin \ Sound

in Marvin \ Sound

Maybe your sample rate is too high or your MOD files are too complex. Additionally, your 286 card cannot magically widen the system bus. It is still an XT bus.

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Re: ID help: Taiwanese CGA/mono(?) video board + ROM type

Posted on 2020-12-31, 17:30

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

VileR wrote on 2020-12-31, 17:06: Still can't find any data/jumper info about that one, but at least that does confirm it as CGA. Which jumpers? I only see one jumper. J2 and J3 look suspiciously like RF modulator and light pen connectors, if you ask me.

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Re: ATI Color Emulation Card

Posted on 2020-12-31, 16:47

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

Anonymous Coward wrote on 2020-12-24, 01:52: Does anyone know where this card was found? Was it a system pull? Presumably on a junk pile. Pin headers don't bend themselves. There's also some visible corrosion.

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Re: ID help: Taiwanese CGA/mono(?) video board + ROM type

Posted on 2020-12-31, 16:38

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

Well, the board does have 16 KiB of video memory and no 16(.257) MHz oscillator. That screams CGA. I can only speculate about the nature of the second RCA jack. Maybe separate composite signals with and without color? As far as the ROM chip is concerned, try to get data sheets for both variants and …

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Re: Early Covox uses:

Posted on 2020-12-28, 13:12

by

by Benedikt

in Marvin \ Sound

in Marvin \ Sound

FreddyV wrote on 2020-12-27, 19:11: Speech synthesis hardware was doing the calculation, here, it is a simple DAC, the CPU will need to do everything and it may be too slow. Unless it's diphone concatenation. Then it's primitive.

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Re: Early Covox uses:

Posted on 2020-12-26, 20:02

by

by Benedikt

in Marvin \ Sound

in Marvin \ Sound

kolderman wrote on 2020-12-26, 19:25: Does that Tandy laptop have Tandy sound? If not, one nice use of a COVOX plug is in emulating Tandy sound using TEMU. I doubt that a 7.16MHz machine will be able to run TEMU. Doesn't it need a 386?

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Re: Why is ADPCM so important?

Posted on 2020-12-26, 16:10

by

by Benedikt

in Marvin \ Sound

in Marvin \ Sound

In my opinion the biggest advantage of the various types of adaptive differential pulse code modulation techniques is their relatively low complexity overhead compared to normal linear PCM or companded PCM. Typical variants allow you to save 50% space with relatively small quality loss. The IMA …

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Re: ATI Color Emulation Card

Posted on 2020-12-23, 22:15

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

Good point! I missed that somehow. It just occurred to me that the switch settings might be similar to those of the ATI Graphics Solution. The following diagram is from its manual. (AGA is Commodore's OEM name for that card.) aga_switch_settings.png Assuming that the meaning of the individual …

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Re: How does onboard Soundblaster emulation work???

Posted on 2020-12-23, 10:55

by

by Benedikt

in Marvin \ Sound

in Marvin \ Sound

Maybe this thread is what you are looking for: VIASBCFG - VIA SBPro configuration tool for VIA VT8231 & VT82C686/A/B chipsets (v0.12d)

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Re: Socket 5 - Dallas RTC replacement gone bad

Posted on 2020-12-23, 10:37

by

by Benedikt

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I guess it's time to go through the checklist: Did you work in an ESD-safe environment while handling the motherboard? How smoothly did the desoldering go? Could you have pulled out a VIA? Is the new RTC chip compatible and inserted the right way around? Does the keyboard work on a PS/2 port with an …

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Re: ATI Color Emulation Card

Posted on 2020-12-22, 13:24

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

Interesting. So it does have the same gate array, just like I assumed. It is also not a pure color emulation card, because it clearly has a composite video header and there are too many traces running to the DE9 socket. There is no 16(.257)MHz oscillator, though, i.e. the MDA/Hercules pixel clock is …

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Re: Newly written driver(s) for Sierra's Creative Interpreter – Starting with Plantronics ColorPlus

Posted on 2020-12-15, 11:52

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

I've thought about audio drivers, as well, but it does not have the highest priority, right now. Anyway, Ravi's Sound Drivers (also LGPL) would then be a good starting point.

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Re: Newly written driver(s) for Sierra's Creative Interpreter – Starting with Plantronics ColorPlus

Posted on 2020-12-13, 11:08

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

NASM expects the prefix within the square brackets and with a colon as separator. Rewriting the offending line of code like this should work: Copy code to clipboard 1 mov [cs:.AddLine-2],ax But I'm not sure about self-modifying code in a dynamically loaded driver.

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