Heh, I might manage up to E1:M6 in text mode, ('coz I know those well enough) but after that would struggle. The question is, is it better than the aalib doom. 🤣

(Though the real competition looks like this one using libaca with SDL ports... https://vimeo.com/139774508 )

I'm having strange centering issues with a CL-GD5428 when using UniVBE, the screen is shifted to the right. Any ideas on how to fix that?

appiah4 wrote on 2021-07-20, 21:53:

I'm having strange centering issues with a CL-GD5428 when using UniVBE, the screen is shifted to the right. Any ideas on how to fix that?

Same happens to mine, I usually fix it by adjusting the monitor.

BTW i'm adding a new mode with vertical monitor support, similar to TOOM (Tate Doom, featured in the LGR youtube channel https://youtu.be/V74eiGAbvDk). For now it renders on a backbuffer and then transposes and scales the frames to a VGA planar mode (320x400). The aspect ratio will be wrong, but this way is much easier to implement. If this results to be very slow, i'll do the same but without the scaling process on a 320x350 resolution, leaving black bars on the borders.

ViTi95 wrote on 2021-07-20, 17:23:

Edit: Do exist any ISA video card that supports LFB? The only card I have that is supposed to support it is a Cirrus Logic GD-5429, but UniVBE doesn't enable it at all (even with less than 16Mb of RAM). The same motherboard works fine with a GD-5426 and LFB enabled. Maybe someone here can try this new mode with a compatible ISA one.

dug out my old comments answering similar question:
"afaik only ISA Tseng ET4000 and ATI Mach64 supported LFB, with ATI being only one allowing mapping more than 1MB at once. ISA is limited to 24 bits of address space = up to 16MB, so new Bios option appeared in 386 and later motherboards called "Memory Hole At 15M-16M" to make room for 1MB of ISA card address space when computer has more than 15MB of ram. If you had 4MB ATI Mach64 and wanted it all mapped linearly you had to contend with 12MB ram max installed etc"

"Bios companion book covers VGA LFB ISA bios options https://books.google.com/books?id=69648Y1sOew … &q=LFB+ISA+card Page 270
ET4000: 3d4h index 36h (R/W): Video System Configuration 4 Linear addressing if set (4000) Video Memory is mapped as a 1 Meg block above 1MB. 5 ? Enable Tseng Addressing Mode (W32x) If set enables Memory Mapped registers. Three MMU areas exist.... 3CDh (R/W): Segment Select 6-7 Segment Configuration. 2 1M linear memory 3d4h index 30h (R/W): (W32x ?) bit 0-? Linear Frame Buffer Address in units of 4Mb"

"looking up VBE/AF documentation they only supported banked modes for ET4000/6000 chips"

tldr: there is a possibility ISA ATI Mach64 will support LBF

Here is DOOM on EGA dithering samples.

Top left is superior to the others in every way IMO.

Hello ViTi95,
I know maybe it's too much to ask but... any chance to see FastDoom running on Next186 FPGA core (recently ported on MiST and SIDI board)?
It's a 0186 / 286 implementation, but CPU clock is 50 MHz, SDRAM clock is 100 MHz, it has Disney Sound Source / COVOX implementation, and even MPU-401 for MIDI support.

https://github.com/mist-devel/mist-binaries/t … r/cores/next186

It would be awesome, thank you!

32bit protected mode is almost impossible to convert to 16bit. It needs a totally new engine.

@Cyberdyne is right, it's a huge task as nearly all the code has to be rewritten (Doom was built with 32 bit registers in mind)

I understand. Thank you so much anyway for your kind feedback. 😉

Guess if you want Doom on MIST you have to follow this https://github.com/MiSTer-devel/ao486_MiSTer

Thank you, but the ao486 core is too big for MiST and SIDI. On the other hand, it seems that Next186 core manages better the smooth scrolling of games like Crystal Caves, Commander Keen etc.

Yeah I meant to keep an eye on it, in case they do a super tight recode to fit early GPU emulation in alongside it or something, then it might fit a MIST with plain VGA.

Nice Doom port!

On my Socket 7 computer with a K6-2+/450 CPU and S3 Trio3D/2X video card the performance improved even in mode Y.

I ran the following benchmark using The Ultimate Doom WAD demo3 without sound for each executable.
- Original DOOM.EXE: 3863 gametics in 1049 realtics. FPS: 128.889 (Calculated using 35*gametics/realtics)
- FDOOM.EXE: 3864 gametics in 958 realtics. FPS: 141.066
- FDOOM13H.EXE: 3864 gametics in 426 realtics. FPS: 317.191
- FDOOMVBR.EXE: 3864 gametics in 401 realtics. FPS: 337.084
- FDOOMVBP.EXE: 3864 gametics in 402 realtics. FPS: 336.165
- FDOOMVBD.EXE: 3864 gametics in 868 realtics. FPS: 155.382

I enabled the K6 write combining prior to running the benchmark. One suggestion here which is to remove the verbose which reports that the real interrupt vector has been modified, there is an utility called SS (SUNSYS Setup Utility) for DOS/32A which has an option to disable these messages from displaying up.

Thanks for the idea @Gmlb256, the latest release (0.8.7) has those messages disabled. Didn't know it was possible to configure DOS/32A in so many ways!

My idea brainfart regarding asset dithering:

(Probably not for cache/memory reasons) On load of a graphic/pic/etc, alternate between a premade LUT of four [256][4] per col/row for a 2x2 dithered load (so darker colors get dithered appropriately)? Maybe a little CLI tool to swizzle a wad's graphics to a EGA-ready dithered/optimized pwad? Edge detection to make outlines on monsters and items (inspired by id's earlier Catacombs/Hovertank)? Individual tweak LUTs made for certain sprites i.e. flesh to switch to EGA greys/whites (like id's earlier games)?

The 4 [256] LUTs would differ slightly in saturation and intensity and would map to the EGA colors to retain some of the tone/detail.

so what's next? PC-9801 modes?

leileilol wrote on 2021-08-24, 22:34:

...

The LUT idea works very well for dithering the B&W modes, since it avoids lot's of branches, so I guess it's also a good idea for 4-color and 16-color modes. For now I won't be doing anything very specific for CGA/EGA modes, since most of the 8-bit ISA cards aren't able to sustain good framerate with the 320x200 resolution. I guess it's possible to implement a dithered version for the 640x200 EGA resolution, since the loss of resolution won't be as noticeable, but again it will be slow as hell (EGA cards are insanely slow).

For now the roadmap is this one:

• Add support for new sound cards (AC97, Game Blaster, Tandy 3-voice, OPL2LPT, IBM PS/1 DAC, ... ?)
• Re-enable hardware mixing on Gravis Ultrasound cards (disabled 7/24/95 on the Apogee Sound System), original code is missing
• Add support for some obscure video cards (IBM PGC, IBM 8514, TIGA, ... ?)
• Fix CGA 320x200x4 mode (ugly as f***)
• Speed-up new video modes (CGA, EGA, Hercules,...) since they are updating the whole screen every frame (use partial update as in 13h and VBE2 modes).
• Fix FreeDoom 2 MAP15
• Add SIGIL support

Also the development process will slow down a little bit, my girlfriend broke up with me some weeks ago and I'll spend some time on getting better.

I was thinking on load of the pic/texture data rather than real-time dithering the screen. Skipping the dither on the 3d sprites would probably help for visual clarity (and dithered sprites would shimmer a lot)

Great project , keep going =)

P.S. oh i know how it is, keep your self. And don't let girls destroy you that easily. I never let me crash on someone. just relation ships without that deep feelings.

Hello ViTi95, I took some time to test the latest version (Fdoom v0.8.7) and I noticed it's a bit slower compared to the version I tested before v0.8.
With the Am5x86 133 and the Permedia 2 graphics card it lost less than half fps (49,89 49,56), the same was with virge card (50,91 50,53).
At 160 mhz the performance loss is lower (61,22 60,87).
The same pattern with the UMC cpu: 25,19 24,94

All those values are the fps.