Super VDP for SegaCD

[tomaitheous]

I thought I read somewhere that the SegaCD was going to receive a video upgrade but was canceled. Considering the ASIC is sort of a mismatch for the Genesis original VDP, it would make sense that the extra 68k@12.5mhz and the ASIC be paired with the Super VDP of a version of it (which isn't really super - just a simple BITMAP display controller - probably low cost to boot).

What do you guys think?

[evildragon]

The ASIC in the Sega CD was designed to output tiles to the Genesis VDP.

What you are thinking about is exactly what the 32X does, adds the Super VDP, even to the Sega CD for access.

Don't forget, most of the people here don't even know what a Super VDP is.

[Joe Redifer]

The video would still have to be handled externally like it is with the 32X... wires going everywhere.

[tomaitheous]

Yeah, I know the ASIC output is 4bit pixel packed tiles, but who's to say it wasn't originally for variable sized bitmap images? I mean changing internal rom of the ASIC chip couldn't have been that difficult.

And it seems silly that they added an additional 68k without the increased video hardware (and the fact that the sub-cpu can't access the VDP) to go along with it. It's a bit overkill just to handle additional functions like collision detection and other game physics. In all honestly they could of cut cost and included a cheaper/lower cost MCU. To me, a 68k@12.5mhz + ASIC + Super VDP(or something similar) makes perfect sense. Take out the additional VDP and well.. it's kind of a waste of cost/effort IMO.

Just my two cents..

[evildragon]

If the Sega CD had video mixing hardware, then the 32X wouldn't have worked out too well. TWO video overlay systems? That sounds like trouble.

Besides, I don't think the side card connector on the Genesis even has HSync and VSync, let alone YS for the Genlock system.

[tomaitheous]

If the Sega CD had video mixing hardware, then the 32X wouldn't have worked out too well. TWO video overlay systems? That sounds like trouble.

Besides, I don't think the side card connector on the Genesis even has HSync and VSync, let alone YS for the Genlock system.

Are you sure? YS should be on the expansion connector. I'll have to dig around my docs and see if I have the expansion layout.

[evildragon]

Are you sure? YS should be on the expansion connector. I'll have to dig around my docs and see if I have the expansion layout.

I don't think it is, im 70% certain on this.

[Aarzak]

I used to believe that the combined hardware of the Genesis+Sega CD was capable of handling at least really close conversions of Sega's coin-op sprite monsters (Outrun, After Burner, Super Hang-On, Space Harrier........NOT "Galaxy Force II", good god) with all of that combined hardware under the belt, and I bet many people back in 1990/1991 (when the Mega CD was announced and released) believed that as well.............but we were all dead wrong.

The MCD, 32X and Saturn all suffered from bottlenecks or lack of features that impaired their performance or graphic output, didn't they? Seems like the SMS/GG, Genny and Dreamcast were the only solidly developed Sega consoles, especially for their time.

[tomaitheous]

Anyone have scans of early specs? Maybe from some Japanese mags?

[j_factor]

Saturn's performance impairment came from really poor SDK's and an overall lack of dev support from Sega. That kind of ties in to how it was more successful in Japan -- shitty devkits aren't a big deal for RPGs and dating sims. But developers making more intensive games really had to go out of their way if they wanted to support the Saturn. I believe it was Core Design who created their own Saturn middleware from scratch by programming it in assembly, and Psygnosis made unauthorized modifications to their dev systems. Most developers would never go to such a bother (Core and Psygnosis were a bunch of crazy Amiga programming veterans who probably relished the challenge). But why am I talking about the Saturn?

If the Sega CD had video mixing hardware, then the 32X wouldn't have worked out too well.

All the more reason it should've had it. Maybe then they wouldn't have gone ahead with the ill-advised 32x.

[Aarzak]

Let's not dwell anymore on Sega's lapse of judgement between 1992-1997.

[j_factor]

You mean 1992 to present.

And 1983 to 1990.

Really, Sega sucks.

[Aarzak]

Hey, they were trying their damnest with the Master System but Nintendo shut them out! And they were ripping arse (heh) in the arcades throughout the mid-to-late '80's.

[Psy]

Saturn's performance impairment came from really poor SDK's and an overall lack of dev support from Sega. That kind of ties in to how it was more successful in Japan -- shitty devkits aren't a big deal for RPGs and dating sims. But developers making more intensive games really had to go out of their way if they wanted to support the Saturn. I believe it was Core Design who created their own Saturn middleware from scratch by programming it in assembly, and Psygnosis made unauthorized modifications to their dev systems. Most developers would never go to such a bother (Core and Psygnosis were a bunch of crazy Amiga programming veterans who probably relished the challenge). But why am I talking about the Saturn?

True, and later on Japanese developers did figure out how to work with the Saturn.

All the more reason it should've had it. Maybe then they wouldn't have gone ahead with the ill-advised 32x.

That would have made the SegaCD even more expensive, if Sega had put sprite rotation and scaling into the VDP of the Genesis the SegaCD could have been cheaper, really the lack colors on the Genesis was a minor issue as most people used RF hookups that caused color bleeding anyway (turn the sharpness of the TV all the way down when playing Genesis games to emulate how the Genesis looked back in the day and remember even if you had composite back then TVs have far better comb filters now).

[tomaitheous]

That would have made the SegaCD even more expensive, if Sega had put sprite rotation and scaling into the VDP of the Genesis the SegaCD could have been cheaper, really the lack colors on the Genesis was a minor issue as most people used RF hookups that caused color bleeding anyway (turn the sharpness of the TV all the way down when playing Genesis games to emulate how the Genesis looked back in the day and remember even if you had composite back then TVs have far better comb filters now).

I don't think it would have been much more. They could have easily eaten the small cost. The Super VDP is a very simple/low cost bitmap display controller. I bet the add confusion of the video cable scheme probably deterred more than anything (assuming the rumors of the additional VDP in the original design were true).

Worst cast scenario, they could have used an upgraded TI VDP(with a faster DMA for screen updates, i.e. scaling/rotation) for the base unit that only the sub-cpu could access, and have software turn off the Genesis VDP - no signal mixing. They'd just have to supply a mixer cable like they did for the stereo audio part, so you could still see video for Genesis carts.

Anyway, I'm not trying to discuss Sega's poor decision on the matter. I just like to discuss some of the evidence that the additional VDP was indeed part of the original design by looking at the final release design.