Re: USB2ISA? I'm Skeptical...

Posted on 2020-09-10, 10:48

by

by Benedikt

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

cyclone3d wrote on 2020-09-10, 07:59: I haven't actually tried it with an ISA card yet but it looks like it will auto detect resources... at least on non-pnp cards. I think you may have to manually add the needed resources for pnp cards from the looks of it but not 100% sure. Not the other way …

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Re: CGA monitor (Samtron SC-452) in need of revival

Posted on 2020-09-10, 10:44

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

If that guy down the street is running a CRT TV repair shop, he might have access to one of these babies: https://youtu.be/YikOY8WTnLU. (Title: Rejuvenating a Macintosh CRT with equipment from 1969)

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Re: Using an ISA VGA card on an AVR

Posted on 2020-09-06, 12:35

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

Could this project be transferred to an STM32? They are 3.3V parts, but 5V tolerant and the 3.3V I/O voltage is 5V TTL compatible. The higher processing power, integrated DMA peripherals and often integrated USB support would simplify a lot of things. If 5V TTL compatibility is not sufficient, a …

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Re: Early Video Codec Comparison with Samples

Posted on 2020-09-05, 09:21

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

If you really want to go the extra mile, and need a very particular dithering algorithm which isn't supported by 'paletteuse'... then you could use FFMPEG to break up the video into .png frames, and feed them to something like ImageMagick (which even supports custom ordered-dither patterns, for …

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

Posted on 2020-09-04, 21:22

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

Interesting! Now that I think about it, the memory models of the M24 640x400 monochrome mode and the 320x200 16-color Plantronics mode are actually quite similar. The second and third line in every group of four lines are swapped, but you would still get a somewhat sensible picture. Let me try …

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

Posted on 2020-09-04, 20:06

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

I was previously thinking of making a driver to support the 640x400 monochrome mode from the Olivetti M24 as mentioned here. I have an old Toshiba T1000SE laptop which supposedly supports this mode on its monochrome LCD screen and could potentially have a better dithered mode than the stock 640x200 …

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

Posted on 2020-09-04, 10:40

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

I think that while the original Plantronics ColorPlus card came very early, somewhat widespread support in budget PCs wasn't a thing until the mid to late 80s, in other words until the gaming industry had largely moved on to EGA and the Amiga. Another important factor is speed: While EGA can be …

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Re: Anyone know where to find ATX 20 pin -5v adapters in 2020?

Posted on 2020-09-03, 16:46

by

by Benedikt

in Marvin \ Sound

in Marvin \ Sound

It could be done with a small solderable breadboard. Even without, in fact. If you don't need fancy looks, take a screw terminal strip and call it a day. Yes, a clean mod would put everything inside the PSU itself, but for a beginner project let's not open that. I'm not aware of ATX-related examples …

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

Posted on 2020-09-03, 15:58

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

I can only assume that the mode itself went largely unnoticed and that not only game developers, but even the system owners themselves often did not know about it. In other words: Bad marketing all around! Budget PC manufacturers could have used this kind of driver to boost their sales, but didn't. …

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Re: Anyone know where to find ATX 20 pin -5v adapters in 2020?

Posted on 2020-09-03, 15:42

by

by Benedikt

in Marvin \ Sound

in Marvin \ Sound

I'd recommend the DIY route, nonetheless. You need a 7905 negative voltage regulator to turn the -12V into -5V. It is a three-pin device that looks roughly like a transistor. The 7905 needs a 100nF capacitor for its input voltage and another one for its output voltage. That's it!

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Re: Using an ISA VGA card on an AVR

Posted on 2020-09-03, 12:06

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

Yes with a disassembler (e.g. debug.exe in DOS) you could easily take a peek at the BIOS init code too. I'd rather read out the entire VGA BIOS at once and use more sophisticated tools like Sourcer Commenting Disassembler v.8 or the Ghidra disassembler/decompiler. And with a microcontroller you can …

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Re: Using an ISA VGA card on an AVR

Posted on 2020-09-03, 11:46

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

When in doubt, a disassembler can help. The VGA BIOS is not a black box, after all. Whether expanding the data bus to 16 bits makes sense depends on whether the ATmega 2560's external memory interface is involved. AFAIK, it supports 8 bit buses, only.

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Re: What is the purpose of "Restart into MS-DOS mode" for you ?

Posted on 2020-09-03, 11:33

by

by Benedikt

in Marvin \ Software

in Marvin \ Software

The deciding factor is usually whether a program tries to set up its own protected mode without DPMI. A DPMI compatible DOS extender would notice that there already is a DPMI (provided by Windows) and simply use that, instead. Certain types of hardware access can also be problematic. The timer, for …

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Re: Video playback on a 286? - here's how to do it

Posted on 2020-09-02, 16:25

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

The later demo 8088 Domination is even more advanced.

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Re: Using an ISA VGA card on an AVR

Posted on 2020-09-02, 16:20

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

In case of memory word access via 8-bit bus there have to be two MEMW or MEMR strobes, because you are changing the address in between. If there were only one, you would only access one of the two bytes. Maybe the interface to the ISA card is somehow flawed. Can you somehow verify that the VGA card …

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Re: Using an ISA VGA card on an AVR

Posted on 2020-09-02, 14:42

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

Interesting project, indeed! What happens on 16bit memory read instructions on an 8bit ISA bus? My current behaviour is just to do 2 bus cycles: memoutb(addr, *val & 0xFF); memoutb(addr + 1, (*val << 8) & 0xFF); But that also causes 2 strobes of the IOR/IOW lines. How does a normal CPU behave here? …

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Re: Tandy Nano - 3 Voice Soundcard ISA - Lowprofile

Posted on 2020-09-01, 15:07

by

by Benedikt

in Marvin \ Sound

in Marvin \ Sound

The PS/1 sound card uses a big custom chip with integrated PSG, but it should be compatible. A port list is probably fine, but you'll have to wait for matze79's answer. What does "Emul" stand for? An emulator TSR using int 0c0h or something else?

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Re: Tandy Nano - 3 Voice Soundcard ISA - Lowprofile

Posted on 2020-09-01, 14:53

by

by Benedikt

in Marvin \ Sound

in Marvin \ Sound

FreddyV wrote on 2020-09-01, 14:31: Hi, what are the I/O port of Tandy Nano ? IIRC, the supported ports are at least 0c0h and 2c0h. Maybe also 0e0h, 1e0h and 2e0h. The PS/1 sound card, on the other hand, uses port 205h. If I were you, I'd allow arbitrary port numbers with 0c0h as the default value. …

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Re: Video playback on a 286? - here's how to do it

Posted on 2020-09-01, 13:23

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

Jo22 wrote on 2020-09-01, 12:47: Thanks for the information! 😀 This makes me wonder - how compared it to CD-i ? Skimming through it, CD-i appears to be just yet another constant bit rate format, i.e. one with very similar limitations. I don't see any aspect ratio support beyond 4:3 and 16:9, either …

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Re: Video playback on a 286? - here's how to do it

Posted on 2020-09-01, 12:19

by

by Benedikt

in Marvin \ Video

in Marvin \ Video

Yes, I second that. MPEG-1 wasn't that bad, actually. Just watched a commercial made VideoCD (StarTrek IV) and it looked fine. Even on the big screen (BD Player). In fact, it aged better than some VHS cassettes that I've got. :) The biggest problem with MPEG1 VideoCDs wasn't so much the coding …

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