Search found 3127 matches

by Stef
Tue Jan 17, 2023 9:27 am
Forum: Sound
Topic: New Documentation: An authoritative reference on the YM2612
Replies: 863
Views: 770286

Re: New Documentation: An authoritative reference on the YM2612

Yeah the address / register write delay seems quite short, still not short enough to use a Z80 16 bit write as LD (YMPORT), HL (16 cycles) or LD (YMPORT), DE (20 cycles) I really wanted to use it as even if high byte is written first (at addr + 1), it's not much of an issue as both address ports sha...
by Stef
Tue Jan 17, 2023 1:14 am
Forum: Sound
Topic: New Documentation: An authoritative reference on the YM2612
Replies: 863
Views: 770286

Re: New Documentation: An authoritative reference on the YM2612

I finally took sometime to make some tests about the minimum safe write timings for the YM2612 / YM3438 chip. I made a lot of tests but still I couldn't test every cases and every registers but hopefully that is enough to confirm (or not) data we got from official documents. I made all my tests usin...
by Stef
Fri Jan 13, 2023 11:12 am
Forum: Megadrive/Genesis
Topic: Regarding the 480i mode on Genesis. . . .
Replies: 13
Views: 1307

Re: Regarding the 480i mode on Genesis. . . .

The flickering you're speaking about is because the high resolution mode in done in 448i/480i (note the 'i' which means "interlaced resolution"). This is because that was the way TV was working back in day. Full resolution was made in 2 frames, one frame displaying odd lines, the other frame display...
by Stef
Tue Jan 10, 2023 8:33 am
Forum: Megadrive/Genesis
Topic: Regarding the 480i mode on Genesis. . . .
Replies: 13
Views: 1307

Re: Regarding the 480i mode on Genesis. . . .

This is afaik the difference between the 2 interlaced modes on MD, one use 8x8 tiles while the other switch to 8x16 tiles.
by Stef
Fri Dec 16, 2022 10:21 am
Forum: Megadrive/Genesis
Topic: Regarding the 480i mode on Genesis. . . .
Replies: 13
Views: 1307

Re: Regarding the 480i mode on Genesis. . . .

That is just the way the register is wired, actually bit 0 is for interlaced mode while bit 1 is for interlacing type (which is meaningless in no interlaced mode).
by Stef
Thu Dec 15, 2022 10:23 am
Forum: Megadrive/Genesis
Topic: Regarding the 480i mode on Genesis. . . .
Replies: 13
Views: 1307

Re: Regarding the 480i mode on Genesis. . . .

As Enforcer said, there is 2 interlacing modes on Sega Genesis, and one of them allow to preserve correct aspect. It's just that Sonic 2 used the other mode. See VDP register 0C description here: https://segaretro.org/Sega_Mega_Drive/VDP_registers LS1-LS0: Interlace mode: 00 = no interlace; 01 = int...
by Stef
Fri Dec 09, 2022 11:06 am
Forum: Video Display Processor
Topic: Capabilities of various VDPs at parallax effects
Replies: 22
Views: 1643

Re: Capabilities of various VDPs at parallax effects

Unfortunately the comparison video is completely off, i already saw it and was surprised about the title as benchmarking and compare VDP performance of the different system sound like a rather difficult task. And here what he did is basically just trying to compare the VRAM write speed from CPU for ...
by Stef
Tue Oct 11, 2022 7:12 am
Forum: SGDK
Topic: How to duplicate sprites using VRAM tiles once?
Replies: 5
Views: 2055

Re: How to duplicate sprites using VRAM tiles once?

SPR_loadAllFrames(..) This couldn´t be used due to severe memory restrictions; There is a 1000 tiles framebuffer in VRAM (some screens have more than 900 different tiles at once), and around 700 free tiles for 20+ sprites... If I execute this sentence: SPR_setVRAMTileIndex(entidad[aux].spr) without...
by Stef
Mon Oct 10, 2022 9:16 am
Forum: SGDK
Topic: How to duplicate sprites using VRAM tiles once?
Replies: 5
Views: 2055

Re: How to duplicate sprites using VRAM tiles once?

You can do that by using SPR_setVRAMTileIndex(..) so you define where the sprite tiles are located in VRAM. You have this function SPR_loadAllFrames(..) function which load all frames of a SpriteDefinition so you can easily share the tile indexes along several sprites then. The sonic sample show an ...
by Stef
Fri Aug 26, 2022 8:11 am
Forum: Announcement
Topic: Hello you all
Replies: 8
Views: 4396

Re: Hello you all

Welcome on the board ! As you noticed indeed forums are not as active than they were some years ago, new tools as Discord appeared and lot of people moved there. I've to admit myself that i rather prefer to use Discord (there is a SGDK discord server), it's just faster to discuss / provide support u...
by Stef
Mon Aug 22, 2022 8:24 am
Forum: Demos
Topic: [Sega MD] various test roms for emu's
Replies: 3
Views: 987

Re: [Sega MD] various test roms for emu's

Thanks ! These are very useful test ROMs !
First time i saw BlastEm failing on that much tests.
I don't even speak about Gens who fail everywhere :lol:
by Stef
Tue Jul 19, 2022 10:00 am
Forum: SGDK
Topic: polygon is not drawn
Replies: 19
Views: 2778

Re: polygon is not drawn

alko wrote:
Fri Jul 15, 2022 6:57 pm
:oops:

Code: Select all

 line = MEM_alloc( sizeof(Line));
No, it's really overkill and you may not release it properly later.
Just use static structure for that:

Code: Select all

 Line line;
line.pt1.x =0;
line.pt1.y =0;
line.pt2.x =100;
line.pt2.y =100;
line.col=10;

BMP_drawLine(&line);
by Stef
Tue Jul 19, 2022 9:58 am
Forum: SGDK
Topic: Form day to night, impossible to compile. gcc.exe: fatal error: -fuse-linker-plugin, but libto_plugin-0.dll not found
Replies: 2
Views: 1159

Re: Form day to night, impossible to compile. gcc.exe: fatal error: -fuse-linker-plugin, but libto_plugin-0.dll not foun

Do a complete clean of your project, you may have dirty .s files somewhere..
I also experienced it and fixed it just by cleaning some intermediate .s file not properly cleaned
by Stef
Tue Jul 19, 2022 9:55 am
Forum: Demos
Topic: Instruction timing test (68000)
Replies: 7
Views: 1579

Re: Instruction timing test (68000), wip.

Very interesting but i'm not sure to understand the VRAM/VSRAM cycles number. 85 cycles is for VRAM read operation during display ON i guess and continuous operation ? what represent the first 19 cycles ? single VRAM read operation ? I'm also very surprised by the 11 cycles obtained on long VRAM wri...
by Stef
Wed Jul 13, 2022 7:31 am
Forum: SGDK
Topic: polygon is not drawn
Replies: 19
Views: 2778

Re: polygon is not drawn

Kega isn't accurate, nor Gens is. You should test with BlastEm to see if you still have the same problem.
About the font, you can just "overwrite" it with your own tiles if you don't use it :)