Search found 178 matches

by Huge
Tue May 01, 2018 10:30 pm
Forum: Hardware
Topic: Some questions about Saturn HW
Replies: 18
Views: 1596

Re: Some questions about Saturn HW

Actually... if the VDP1 is shrinking a texture, and there are transparent and opaque texels "overlapping" in a given place, does the opaque texel always get drawn? (i.e. does it write to the same pixel on the framebuffer multiple times within a line?) I think it is different in each mode. With Scal...
by Huge
Tue May 01, 2018 10:17 pm
Forum: Hardware
Topic: Some questions about Saturn HW
Replies: 18
Views: 1596

Re: Some questions about Saturn HW

When reading doc and forums, I understand VDP1 will adapt texture to polygon. It polygon is 32x32 and texture 64x64, I understand will shrink texture to 32x32 and then change shape to adapt to polygon shape. But you wrote that will "show only 32x32 and then waste time checking pixels that don't end...
by Huge
Tue Apr 24, 2018 11:01 pm
Forum: Hardware
Topic: Some questions about Saturn HW
Replies: 18
Views: 1596

Re: Some questions about Saturn HW

You'd need to do quite some magic to "defragment" your sprite table in a way like that, although I suppose it is possible, especially if you use very large sprites. But I don't think it's practical because for animation-heavy games, the VRAM is not enough and you need to load new sprites from low ra...
by Huge
Tue Apr 24, 2018 2:32 am
Forum: Hardware
Topic: Some questions about Saturn HW
Replies: 18
Views: 1596

Re: Some questions about Saturn HW

End codes are just Sega's idea of speed optimization. They tell the VDP1 to stop sampling the texture, so if large parts of the texture are transparent, you can get a potentially significant speedup at drawing.
by Huge
Sun Apr 22, 2018 8:58 pm
Forum: Hardware
Topic: Some questions about Saturn HW
Replies: 18
Views: 1596

Re: Some questions about Saturn HW

Though after working on some software polygon routines meant to draw Saturn-like quads I'm left baffled as to why it needs to go through all pixels (is bresenham-like interpolation that hard to do in hardware? serious question), not sure what it's doing internally on that respect. It goes through e...
by Huge
Sun Apr 22, 2018 2:05 am
Forum: Hardware
Topic: Some questions about Saturn HW
Replies: 18
Views: 1596

Re: Some questions about Saturn HW

I don't know if you get overdrawn pixels when you draw a poly where the right side is larger.... logic would dictate that you get dropouts here, but the VDP1 does some aliasing to get around this, but I don't know how. Whenever the line would step diagonally in its slope it draws two pixels (on bot...
by Huge
Sat Apr 21, 2018 10:06 pm
Forum: Hardware
Topic: Some questions about Saturn HW
Replies: 18
Views: 1596

Re: Some questions about Saturn HW

- VPD1 and VPD2: VPD1 writes in framebuffer. VPD2 reads this framebuffer and copy all this info to one of its layers. Then mix all layers and send result to TV: If this is true, then all "sprites" are in one layer. This seems usual way. The Video Panda 1 draws one frame to its framebuffer 0, while ...
by Huge
Thu Aug 10, 2017 12:35 pm
Forum: Mega/SegaCD
Topic: Subcodes only for CD+G ?
Replies: 7
Views: 865

Re: Subcodes only for CD+G ?

If you are on Windows, CD Manipulator can make clonecd compatible dumps with subcode included, and it is free:
http://www.storeroom.info/cdm/

It will write a "cdm" file instead of "ccd" but the format is the same, and it can be renamed and work the same.
by Huge
Mon Nov 21, 2016 8:14 pm
Forum: Hardware
Topic: Cross Products MegaCD Development Kit in action
Replies: 2
Views: 842

Re: Cross Products MegaCD Development Kit in action

Very nice video!

Do we have board photos of the Sega interface card? The longer one in your video (not the SNASM one).
by Huge
Wed Aug 24, 2016 10:39 pm
Forum: Megadrive/Genesis
Topic: Questions on developing a Mega Drive emulator
Replies: 39
Views: 5076

Re: Questions on developing a Mega Drive emulator

There's a few menu screens on the SNES that use interlace mode, but it's pointless. Progressive fonts are perfectly legible too. Yeah but on the SNES you are heavily limited in colours and background layers if you use the interlaced mode. On the Megadrive you are pretty much only limited by whether...
by Huge
Sat Mar 26, 2016 7:27 pm
Forum: Megadrive/Genesis
Topic: Sega TeraDrive motherboard pics
Replies: 29
Views: 12531

Re: Sega TeraDrive motherboard pics

BIOS of teradrive : http://piroxilin.narod.ru/sega/teradrive/bios-27c010.bin And here I was hoping I was gonna get some work stuff done. There goes the day... EDIT: oh, it's the PC BIOS. I wonder if it includes any Tera Drive specific code or not. EDIT 2: by the way before I forget, looks like this...
by Huge
Thu Dec 10, 2015 12:26 am
Forum: Video Display Processor
Topic: VDP 128Kb Extended VRAM mode
Replies: 41
Views: 22122

Re: VDP 128Kb Extended VRAM mode

This reminds me, the recent Megadrive Collected Works has had an interview with the Megadrive hardware designer, Masami Ishikawa, where he talks a bit about the 128Kb VRAM mode. Apparently it was added as an experiment to significantly increase performance, but in the end it unfortunately didn't. Wh...
by Huge
Wed Dec 02, 2015 2:19 am
Forum: Hardware
Topic: Decapping more Genesis chips
Replies: 13
Views: 4483

Re: Decapping more Genesis chips

On the topic of chips with internal ROMs, the DCC possibly has one as well. Although that chip only handled DRAM and Boot ROM access, so it's not that interesting. It got the task of multiplexing digital audio as well on later models.
by Huge
Tue Dec 01, 2015 6:31 pm
Forum: Hardware
Topic: Decapping more Genesis chips
Replies: 13
Views: 4483

Re: Decapping more Genesis chips

Well, I was mostly mentioning what I was told by other developers. MAMEDEV is always crying about not having info on VDP1 timings. The SCSP DSP, I don't have much documents on that, but according to Steve there are docs by Yamaha about the SCSP which I'd assume include the DSP as well. EDIT: nope, w...
by Huge
Sat Nov 28, 2015 5:35 pm
Forum: Hardware
Topic: Decapping more Genesis chips
Replies: 13
Views: 4483

Re: Decapping more Genesis chips

Of course, if you are able to do "lots" of chips, the Saturn has plenty to do: https://upload.wikimedia.org/wikipedia/commons/9/9d/Sega-Saturn-Motherboard.jpg One of the chips here is the YMF292-F, which might even be of interest for you in your project. On that topic, I have a bunch of broken satu...