Detailed information on Sega Virtua Processor (SVP); The MD/Gen DSP used for V-R

[Farid]

V-R being virtua racing. The title couldn't contain the whole game's name.

Anyway, I just stumbled upon detailed docs of the SVG chip Sega used for its Megadrive/Genesis version of the cult arcade racer. It's been written by emulation enthusiast and programmers, Tasco and Grazvydas Ignotas:

SVP document by G. Ignotas
SVP Reference Guide by Tasco
SVP Register Guide by Tasco
Samsung's SSP1601 DSP data sheet (PDF)

### Info ###

Chip: Sega Virtua Processor (SVP)
Part: Sega 315-5750
Type: DSP - custom reportedly based on Samsung SSP16xx core (!precise core model is unknown!)
Clock: Unknown (!reported to be 23Mhz, but unconfirmed!)

(!clock of Mhz can be derived from dividing the M68000's clock [VCLK] by 3!)

The SVP includes an arithmetic-logic unit (ALU) and a 16x16->32 multiplier.

The exact architecture of the SVP is currently unconfirmed.

The V-R cartridge contained:

• Samsung SSP160x 16-bit DSP core, which includes [3]:
  • Two independent high-speed RAM banks, accessed in single clock cycle,
  • 256 words each.
  • 16 x 16 bit multiply unit.
  • 32-bit ALU, status register.
  • Hardware stack of 6 levels.
• 128KB of DRAM.
• 2KB of IRAM (instruction RAM).
• Memory controller with address mapping capability.
• 2MB of game ROM.

It's always interesting to index the ressources about old hardwares used for 3D rendering, hence the thread. Even if it doesn't interest most these days.

 

[Sdw]

Interesting stuff! Must be quite a bit of work behind reverse engineering all that info...

 

[Quaz51]

compare to the starfox Super FX... fight!

 

[Crayon]

Virtua Racing Genesis runs so fast and smooth. And it was one of the early examples of Sega AM's almost supernatural ability to downport state of the art games. Besides an issue with down-track visibility due to resolution, the genesis game really does recreate the gameplay of the arcade. I play it all the time. I love the gameplay and the perfectly balanced challenge. And besides that, I still get a kick out of my Genesis spitting out environments and action that SHOVES STARFOX'S CRYING FACE INTO IT'S PILLOW.

 

[kyetech]

lol crayon.

OK, heres the deal Virtua racing ROCKED on the Megadrive. And I loved Starfox so much that I completed all the routes and found all the secrets. That game was ROCK hard in later levels of the third route.

Starfox had wonderful presentation and atmosphere. and had a superb 1 player game experience. The sound production was awesome.

Virtua racing had pure unadulterated gameplay goodness. Virtua racing was chucking around more comprehensive environments, but there was a certain rawness about the visuals. The framerate and draw distance was poor. But the gamplay was FUCKING superb.

In many senses Daytona on the saturn was the same. V poor frame rates, poor draw distance. (and shit res and shit textures for that matter).... but..... and its a very BIG ASS BUT.... the gameplay was and still is to this day, one of the all time greatest experiences that can be had from a racing game.

F355 (dreamcast) and Sega rally (saturn) FTW.

amen

 

[I.S.T.]

The SVP was just recently emulated for the first time. I believe the latest Picodrive can do it, and I know for a fact that the new emulator Regen can.

 

[Urian]

Its strange but it seems to be one of the Hitachi SH inside 32X.

 

[Megadrive1988]

Cool stuff Farid, thanks for making this thread.

I never really knew anything about the SVP because I wasn't interested in Virtua Racing on Genesis (my reason was I wasn't going to pay $100 for a massively downgraded Model 1 game that would potentially be much better on then-upcoming 32-bit systems) but this is indeed interesting!

 

[mjdted]

Good, I'm guessing this info helps for emulation purposes.

 

[Reznor007]

Emulation purposes is where this came from really. The game is now emulated in a few standalone emulators, and support for the chip was added to MAME/MESS in the latest source update.

 

[Johnny_Physics]

Here's both versions on youtube playing the first track for those interested:

Genesis/Megadrive:
http://www.youtube.com/watch?v=cO7dbgTIUYs

Arcade:
http://www.youtube.com/watch?v=mwh6CxPRt3g

I remember how awestruck I was when I first saw and played Virtua Racing in an arcade, back in '92 I think? 3D wasn't something entirely new to me, but it was so sharp and vibrant compared to the games I'd seen and played on various home computers!
This feeling was only amplified when playing Virtua Fighter and seeing the small touches in animation, like the characters stumbling a bit when they stepped outside the ring or Pai losing her hat when hit hard enough.

 

[hey69]

is it the video? megadrive version is like running at 15fps...

 

[pipo]

F355 (dreamcast) and Sega rally (saturn) FTW.

amen

+1.

I miss the old Sega...

 

[Johnny_Physics]

is it the video? megadrive version is like running at 15fps...

No, it is really, really slow compared to what you would expect in a modern game. It was quite fast compared to Stunt Race FX, a SuperFX-game released a year or two after Starfox, that often seemed to chugg along in a single digits framerate which made steering the jellylike-car quite a challenge.
Here's a vid of it, running on an actual super nintendo.
http://www.youtube.com/watch?v=iEaflsH0Oro


I don't mean to derail this even further so perhaps I'll make a thread later on with some of the stuff that doesn't fit in here.

 

[Johnny_Physics]

edit: completely wrong thread

 

[swaaye]

I rented this for Genesis once. It was neat, but just like Stunt Race FX for SNES (SuperFX2), it just didn't run quite fast enough. It wasn't that much of an issue though. I played the 5-10fps Stunt Race FX to death. These hybrid carts were the only 3D that really was around for home games back then.

I'm not that big on Virtua Racing though. It was a cool arcade racer, but it's a pretty shallow game really. Only a few tracks. Very poor driving simulation. It reminds me of why I went nuts over Gran Turismo and Top Gear Rally when they finally arrived. Ironically, prior to those, the PC had better racers than consoles.

 

[darkblu]

Here's both versions on youtube playing the first track for those interested:

Genesis/Megadrive:
http://www.youtube.com/watch?v=cO7dbgTIUYs

Arcade:
http://www.youtube.com/watch?v=mwh6CxPRt3g

I remember how awestruck I was when I first saw and played Virtua Racing in an arcade, back in '92 I think? 3D wasn't something entirely new to me, but it was so sharp and vibrant compared to the games I'd seen and played on various home computers!
This feeling was only amplified when playing Virtua Fighter and seeing the small touches in animation, like the characters stumbling a bit when they stepped outside the ring or Pai losing her hat when hit hard enough.

unsurprisingly the arcade version blows the genesis version out of the water by resolution alone, if by nothing else, but scene complexity is also clearly higher on the arcade.

at the same time (early '90s) the desktops of the day (read: the pc and the amiga) had something called 4D driving/stunts by mindscape/broderbund - a game i must've spent a lifetime playing. in comparison, VR/arcade looks clearly better (but 4D had an impressive sim model, whereas i can't tell much of VR from that youtube video alone), and VR/genesis is clearly inferior to 4D - in both look and feel.

btw, in the successful emu stories department, just wanted to add that VR/genesis runs fine on genplus/wii. well, if ~15fps can be fine for a racer, that is.

 

[swaaye]

Genesis/Megadrive:
http://www.youtube.com/watch?v=cO7dbgTIUYs

Oh yeah there's the other problem with early 3D games: polygons popping into view not-so-far away. It looks to be running fast enough though!

Stunts is definitely a classic. There were other excellent PC racing games like Grand Prix Circuit, Indianapolis 500, Indycar Racing, and NASCAR. PC was actually pretty big on racing sims for many years. It still gets a few very serious sims, actually.

I think Virtua Racing wasn't anything new to folks other than arcade goers (console-only folks I suppose too then). PC and consoles were way more separate markets back then.

 

[I.S.T.]

Emulation purposes is where this came from really. The game is now emulated in a few standalone emulators, and support for the chip was added to MAME/MESS in the latest source update.

>.> I mentioned that already.

 

[Farid]

Talking about old 3D racers...

4D Sports Driving was really advanced for its time. It supported a complex implementation of replays, for instance.

On the topic of old 3D racers, let's also mention Atari's 1988 Hard Drivin' (Arcade):

This game was mighty impressive back in the days, since not only it was 3D but it had some force feedback.

The problem with this game was that there was virtually no sense of speed at all. So, it wasn't hard drivn' and crashing your car into some obstacle without really noticing you were going too fast

Spoiler

(yes, the pun was intended)

.

Interestingly enough, there were various home versions of this game, including a ZX Spectrum one! But given the topic of the thread, here's a video from the Megadrive/Genesis version:

http://www.youtube.com/watch?v=pi1qT4jBNAg
(I post it in link only since the video once embedded gives a "Sorry, video is not available anymore" error for some reason)

Another 3D polygonal racer game I remember from the heydays of the non-IBM-PC personal computers era, was the Atari ST version (maybe the Amiga version also, but I'm not sure, since I didn't play it) of the Bervely Hills Cop:

http://www.mobygames.com/game/atari-st/beverly-hills-cop/screenshots

The game was a mix between a Rolling Thunder like action shooter and racing sections. Only the drivng section used any form of polygonal 3D, of course. For information, It was released in 1990 according to Mobygames.