Model 3 hardware stepping

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Re: Model 3 hardware stepping

Postby LsrgcBath » Tue Nov 08, 2016 12:10 pm

solitarius576 wrote:
Bart wrote:1. I talked about meshes being uploaded but in fact, Model 3 had very limited memory for this. Only about a megabyte or so. Very few meshes are uploaded this way. The Scud Race and Daytona vehicles (but only the player's) are uploaded because they can be dynamically deformed. But nearly everything else is actually stored in VROM and the VROM is directly connected as a memory region to the Real3D. The CPU can't even see the VROM -- it just passes VROM addresses of meshes and textures to the Real3D, which then can fetch them directly when it needs them.


This is like in older arcade boards and old consoles where even the program was executed directly on the rom, I wonder why they needed to transfer the program into ram on model3, maybe slow execution from rom?
Another question, does sega model 2 have or not texture filtering?, wherever I looked I found contradictory information. With Namco I know that their first platform with texture filtering was System Super 23, but with Sega I don't know if it's Model 2 or Model 3.


If I am not wrong, the first Model 2 use some kind of bilinear interpolation filtering, but i found that in Model 2C, Sega has put a new set of features, things like gourad, trilinear texturing and mipmapping.

Model 3 I believe that in addition to the bilinear filter, also supports trilinear and mipmapping, anyway, bart should has the answers about the guts of the system.

One thing I didn´t know for a long time is that Model 3 has native tiled rendering support. I've tried it, but I've never been able to figure out how this kind of solution works, what are the pros e cons with this kind of render solution.
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Re: Model 3 hardware stepping

Postby Bart » Tue Nov 08, 2016 12:55 pm

solitarius576 wrote:
Bart wrote:1. I talked about meshes being uploaded but in fact, Model 3 had very limited memory for this. Only about a megabyte or so. Very few meshes are uploaded this way. The Scud Race and Daytona vehicles (but only the player's) are uploaded because they can be dynamically deformed. But nearly everything else is actually stored in VROM and the VROM is directly connected as a memory region to the Real3D. The CPU can't even see the VROM -- it just passes VROM addresses of meshes and textures to the Real3D, which then can fetch them directly when it needs them.


This is like in older arcade boards and old consoles where even the program was executed directly on the rom, I wonder why they needed to transfer the program into ram on model3, maybe slow execution from rom?


That's my assumption. You can bet there must have been a very good reason. Model 3 Step 1.0 only has 2MB RAM. Step 2.x expands this to 8MB.

Another question, does sega model 2 have or not texture filtering?, wherever I looked I found contradictory information. With Namco I know that their first platform with texture filtering was System Super 23, but with Sega I don't know if it's Model 2 or Model 3.


ElSemi is the expert on that but my understanding is that it does indeed have bilinear filtering and I think it supports mip-mapping as well, possibly with trilinear filtering. It is a very different beast from Model 3 in terms of architecture, though. A completely different system from end-to-end, although there are a few inconsequential similarities I noticed when I looked at the Model 2 programming manual (e.g., bit field layouts in polygon headers). It even lacked a z-buffer.
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Re: Model 3 hardware stepping

Postby Bart » Tue Nov 08, 2016 1:01 pm

LsrgcBath wrote:One thing I didn´t know for a long time is that Model 3 has native tiled rendering support. I've tried it, but I've never been able to figure out how this kind of solution works, what are the pros e cons with this kind of render solution.


Don't confuse the tile generator with PowerVR-style tiled rendering. Completely unrelated. Whenever I talk about tiles or tilemaps, I'm referring to the System 24 tile generator chip used by Model 2 and 3 for 2D layers. A strange design choice but it probably saved them the cost of providing memory for a second frame buffer. The two tile layers are mixed with the 3D frame buffer output according to a priority setting.
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Re: Model 3 hardware stepping

Postby Bart » Tue Nov 08, 2016 1:09 pm

ferrarifan wrote:Gunblade NY & LA Machineguns are ports of the arcade versions on a home console. Why they should port other SEGA arcade only exclusive titles? Well because the Wii and compared to consoles today are powerful. Also games like SCUD Race is to awesome that got left in the arcades,especially other arcade only titles. But, if SEGA is working on Model 3 ports, doesn't need a emulation code. They just need the actual source code of the hardware. I'm no expert about hardware. I think the reason why certain arcade games are arcade only because of it's short length. Most arcade games aren't that long but some ports will require more game modes like Daytona USA on PSN and XBLA has more features than the original.


Yup. I think that honestly speaking, many of these games would not have been successful at home. Daytona 2, maybe, but by the time the Dreamcast was launched, it was certainly too late for Scud Race and its 1996-era vehicles. They probably decided to focus their efforts elsewhere and decided to do a new Daytona from scratch. Strange that they didn't include the Daytona 2 courses, though.

Many of the Model 3 games just weren't good enough for home ports, IMHO. But several did make it over nevertheless, including VF3, FV2 (I think), Virtual On 2, and Spikeout (a version of which made it to XBox).

I really love the cinematic feel of the Gunblade/LA Machineguns series but the games are extremely short, have limited replay value, and don't translate well to the home format. It's not the same without that giant vibrating machinegun. If you haven't experienced these games in working order (with a functioning gun motor) at an arcade, you're really missing out on the experience. I think to make them interesting in a console format would have required completely redesigning the game mechanics to make them less linear, and at that point you're developing an entirely new game from scratch around a risky, niche franchise. These were expensive and comparatively rare games in the arcades.
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Re: Model 3 hardware stepping

Postby ferrarifan » Tue Nov 08, 2016 1:16 pm

Bart wrote:
ferrarifan wrote:Gunblade NY & LA Machineguns are ports of the arcade versions on a home console. Why they should port other SEGA arcade only exclusive titles? Well because the Wii and compared to consoles today are powerful. Also games like SCUD Race is to awesome that got left in the arcades,especially other arcade only titles. But, if SEGA is working on Model 3 ports, doesn't need a emulation code. They just need the actual source code of the hardware. I'm no expert about hardware. I think the reason why certain arcade games are arcade only because of it's short length. Most arcade games aren't that long but some ports will require more game modes like Daytona USA on PSN and XBLA has more features than the original.


Yup. I think that honestly speaking, many of these games would not have been successful at home. Daytona 2, maybe, but by the time the Dreamcast was launched, it was certainly too late for Scud Race and its 1996-era vehicles. They probably decided to focus their efforts elsewhere and decided to do a new Daytona from scratch. Strange that they didn't include the Daytona 2 courses, though.

Many of the Model 3 games just weren't good enough for home ports, IMHO. But several did make it over nevertheless, including VF3, FV2 (I think), Virtual On 2, and Spikeout (a version of which made it to XBox).

I really love the cinematic feel of the Gunblade/LA Machineguns series but the games are extremely short, have limited replay value, and don't translate well to the home format. It's not the same without that giant vibrating machinegun. If you haven't experienced these games in working order (with a functioning gun motor) at an arcade, you're really missing out on the experience. I think to make them interesting in a console format would have required completely redesigning the game mechanics to make them less linear, and at that point you're developing an entirely new game from scratch around a risky, niche franchise. These were expensive and comparatively rare games in the arcades.
But at least we have arcade emulation.
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Re: Model 3 hardware stepping

Postby LsrgcBath » Tue Nov 08, 2016 1:43 pm

Bart wrote:
LsrgcBath wrote:One thing I didn´t know for a long time is that Model 3 has native tiled rendering support. I've tried it, but I've never been able to figure out how this kind of solution works, what are the pros e cons with this kind of render solution.


Don't confuse the tile generator with PowerVR-style tiled rendering. Completely unrelated. Whenever I talk about tiles or tilemaps, I'm referring to the System 24 tile generator chip used by Model 2 and 3 for 2D layers. A strange design choice but it probably saved them the cost of providing memory for a second frame buffer. The two tile layers are mixed with the 3D frame buffer output according to a priority setting.


Yes, yes, i know this.

All my little knowledge about Model 3 specs had gotten from system16.com, but these days I was boring, and decided to take a look in wikipedia, searching for any Model 3 info, and in the article, there was that tiled-rendering support info, but now I suppose it to be just another case of bad unconfirmed citation of who made the article about it.

https://en.wikipedia.org/wiki/List_of_S ... ga_Model_3

I also imagine that in the SDK docs, some kind of information is not implicit, maybe because the HW abstract and take automatic control of some features, or even some other things that only Sega could especify.
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Re: Model 3 hardware stepping

Postby Ian » Tue Nov 08, 2016 1:51 pm

Bart wrote:
LsrgcBath wrote:One thing I didn´t know for a long time is that Model 3 has native tiled rendering support. I've tried it, but I've never been able to figure out how this kind of solution works, what are the pros e cons with this kind of render solution.


Don't confuse the tile generator with PowerVR-style tiled rendering. Completely unrelated. Whenever I talk about tiles or tilemaps, I'm referring to the System 24 tile generator chip used by Model 2 and 3 for 2D layers. A strange design choice but it probably saved them the cost of providing memory for a second frame buffer. The two tile layers are mixed with the 3D frame buffer output according to a priority setting.
#

I think one reason maybe due to the fact I don't think the model 3 supported ortho projection. Without a 1:1 pixel mapping you'll always get some sort of blurring of the textures. With the tile generator this simply wouldn't have been a problem.
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Re: Model 3 hardware stepping

Postby ferrarifan » Tue Nov 08, 2016 2:42 pm

Yu Suzuki was also involved developing many SEGA arcade hardware like Sega Space Harrier, Model 1, Model 2, and Model 3, and was involved in the development of the Dreamcast console and its corresponding NAOMI arcade hardware.
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Re: Model 3 hardware stepping

Postby Walker69921 » Thu Nov 17, 2016 7:14 pm

Bart wrote:Kind of but not really. Supermodel emulates the PowerPC at a much lower frequency than any of the steppings by default (I think it was 30-something MHz in v0.1a and now is 50 MHz or so) and it uses the same default value regardless of stepping. In fact, the reason this was done in the first place was to improve performance. I've written in other posts why this works. If you choose to run Step 2.x games at their actual 166 MHz, it will of course degrade performance. Try running with VSync and frame throttling disabled and observe the frame rate running at 50 MHz vs. 166 MHz. Modern PCs are fast enough that it doesn't matter in practice because you can achieve 60 FPS performance even with the correct PowerPC clock speed.

We don't emulate graphics chipset timing. We don't know enough about the hardware to simulate it at that level and even if we did, it would be cumbersome and unnecessary resulting in an extremely slow emulation done entirely in software. The graphics hardware is basically a black box. We know the data and commands fed into it and we know what the rendered output should look like. We try our best to use OpenGL to render frames that look as visually similar as we can get them. The actual process doesn't resemble what happens on the Real3D hardware at all but it doesn't matter if the results are indistinguishable.

Higher steppings will tend to push more polygons and more complex scenes. A Step 2.x game like Daytona USA 2 is indeed more performance intensive than Virtua Fighter 3 (Step 1.0) or Lost World (1.5), if only because it is rendering more triangles. There are also some small differences in how data is laid out between Step 1.0 and 1.5/2.x, but nothing major. As with the PowerPC, any modern computer with a GPU from the last ~4-5 years is plenty powerful enough that the difference between emulating Step 1.x and 2.x games is generally imperceptible.
Even with some frame drops,the games are playable,which is not that big of a deal. :) PC's today are even powerful to handle certain emulators( depends on your system) . My system can handle the New 3D Engine.
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Re: Model 3 hardware stepping

Postby ferrarifan » Thu May 25, 2017 11:47 pm

Bart wrote:
ferrarifan wrote:Gunblade NY & LA Machineguns are ports of the arcade versions on a home console. Why they should port other SEGA arcade only exclusive titles? Well because the Wii and compared to consoles today are powerful. Also games like SCUD Race is to awesome that got left in the arcades,especially other arcade only titles. But, if SEGA is working on Model 3 ports, doesn't need a emulation code. They just need the actual source code of the hardware. I'm no expert about hardware. I think the reason why certain arcade games are arcade only because of it's short length. Most arcade games aren't that long but some ports will require more game modes like Daytona USA on PSN and XBLA has more features than the original.


Yup. I think that honestly speaking, many of these games would not have been successful at home. Daytona 2, maybe, but by the time the Dreamcast was launched, it was certainly too late for Scud Race and its 1996-era vehicles. They probably decided to focus their efforts elsewhere and decided to do a new Daytona from scratch. Strange that they didn't include the Daytona 2 courses, though.

Many of the Model 3 games just weren't good enough for home ports, IMHO. But several did make it over nevertheless, including VF3, FV2 (I think), Virtual On 2, and Spikeout (a version of which made it to XBox).

I really love the cinematic feel of the Gunblade/LA Machineguns series but the games are extremely short, have limited replay value, and don't translate well to the home format. It's not the same without that giant vibrating machinegun. If you haven't experienced these games in working order (with a functioning gun motor) at an arcade, you're really missing out on the experience. I think to make them interesting in a console format would have required completely redesigning the game mechanics to make them less linear, and at that point you're developing an entirely new game from scratch around a risky, niche franchise. These were expensive and comparatively rare games in the arcades.
Speaking of source code, i heard some people on SEGA forums said SEGA isn't that great keeping source codes for archives. Actually it is true that SEGA did lose the source code for The House of the Dead. Some may explain why SEGA didn't port some Arcade exclusive titles. Thank goodness for Arcade Emulation because things won't get lost like documentations,ROMS and other stuff. This is why Emulation is important. Read this at http://kotaku.com/5028197/sega-cant-fin ... cade-games. This isn't the SEGA forums.
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