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Use of Slave CPU in comercial games
luisoft - Nov 10, 2010
  luisoft Nov 10, 2010
I do a test using SSF_009_alpha_R1 ( old but work better here ) and many games using Slave cpu underclocked to see the games with bad use of Saturn hardware. Well... MANY games use one cpu only!

In SSF options go to option, program2 and slave SH2 speed % put the value and clic in ok and restart the emulator.

In this option i put many values 1% at 100 and the result...

95% GAMES USE ONLY 1 CPU TO HANDLE FMV!!!

Only 1 game tested use two cpus in FMV - Solar Eclipse ( for me the best fmv in saturn and now confirm why )

Games using 100% slave cpu:

- Daytona USA

- Daytona USA CCE

- Sonic R

- Nights ( not all time )

This games if i put to run in 90% slave cpu i see a small slowdown.

Games using 80% slave cpu:

- Virtua Fighter 2

- Virtua Fighter Kids

- Fighters Megamix

- Sonic Jam ( not all time only when have many poly in screen )

- Solar Eclipse ( only in FMVs and the annimation of beggining the rest of game

run with full speed using 20% of slave cpu)

- Hexen

Games using 60% slave cpu:

- Radiant Silver Gun ( only in 3d bosses the rest of game run at full speed with 30% )

- Initial D

Games using 20% slave cpu:

- Tomb Raider ( running with slave cpu 10% i see small slowdown but have 70% of normal speed )

- Panzer Dragoon 1

- Nipen Manmaru

- Battle Arena Toshinden Remix ( using 10% run a bit slow )

Games using 0% slave cpu:

This games i test with 1% of slave cpu speed to not crash the emulator

and this games not loose any speed with 1% in all time of game.

- All SNK fighting games

- Power Slave

- Duke Nukem 3d

- Cyber Speedway

I dunno how lobotomy create lighting with only one cpu...

 rorirub Nov 12, 2010
Using an emulator isn't a good way to determine what uses what in a game, as far as cpu usage goes. But, if you enable the cpu register tables in SSF (showregister=1 in ssf.ini, I think), you can see a bit more info. Also, you can determine which cpu is active by the five 0-1 numbers in the title bar. They represent the cpus in the saturn, in this order: Main SH2, Slave SH2, 68k, SCU DSP, SCSP DSP. 0 is inactive, 1 is active.

X-Men COTA and Alien Trilogy never activates the slave sh2. And most games use it for something very trivial.

 luisoft Nov 12, 2010

rorirub said:
Using an emulator isn't a good way to determine what uses what in a game, as far as cpu usage goes. But, if you enable the cpu register tables in SSF (showregister=1 in ssf.ini, I think), you can see a bit more info. Also, you can determine which cpu is active by the five 0-1 numbers in the title bar. They represent the cpus in the saturn, in this order: Main SH2, Slave SH2, 68k, SCU DSP, SCSP DSP. 0 is inactive, 1 is active.

X-Men COTA and Alien Trilogy never activates the slave sh2. And most games use it for something very trivial.


Tnx for this info , rorirub!

I do my tests using this way of see register and confirm what i see in old test. 80% games not use slave cpu for fmv and in many cases enable the slave cpu but do nothing or use in really small routines. In my list now the power slave and duke nukem use the slave cpu but really small routines and not use 68k to sound. ( 68k disabled ) and ONLY 1 game tested use SCU - Sonic R! All games disable the SCU and i dunno why...

 rorirub Nov 14, 2010
I never noticed that about Duke 3d... well, Lobotomy were wizards when it came to the Saturn. Still, that's the first Saturn game I saw that doesn't use the 68k to process sound.

All games use the SCU, they just don't use the DSP chip in the SCU. From the top of my head, the SCU DSP is used in Xmen vs SF, Marvel vs SF, Sexy Parodius, Pandemonium, Quake, Dead or Alive, Croc, VF, VF Remix, and a few very late (1998) EA Sports games plus Grandia for FMV.

 mrkotfw Nov 15, 2010
A game won't be 'better' if a game simply uses an extra processor. If anything is written incorrectly (the scheduler or even the context switch part), there would be more overhead than simply using a single processor. That and synchronization issues.

 chenke Dec 22, 2013
How about Zero Divide?
It seems to use both SH2s and the SCU DSP.



  
	
	

		
		

			The programmers have actually made good use of the Saturn's two processors which is why it says FEATURING "SH-2" just above the Zero Divide logo.  This results in a high resolution game with some very high in detail solid looking robotic characters.  The character Zero for example has a metallic shine to his body which changes its look every time he moves.  The arenas even feature 3D backgrounds !  And unlike Sega's own efforts these 3D arenas don't shudder or disappear then reappear as in the likes of Fighters Mega Mix, Last Bronx or Fighting Vipers.  Zero Divide looks much more sold than all of them.


 vbt Dec 24, 2013

chenke said:
How about Zero Divide?
It seems to use both SH2s and the SCU DSP.

certainly, let's find if it uses a lot the slave cpu.

 chenke Dec 27, 2013

rorirub said:
Also, you can determine which cpu is active by the five 0-1 numbers in the title bar. They represent the cpus in the saturn, in this order: Main SH2, Slave SH2, 68k, SCU DSP, SCSP DSP. 0 is inactive, 1 is active.


How can I find the five 0-1 numbers in the title bar?

 chenke Dec 27, 2013
Games using 100% slave cpu:

Grandia (also using main SH-2 + slave SH-2 + SCU DSP in FMV)

Games using 60% slave cpu:

Burning Rangers

Dead or Alive

Zero Divide The Final Conflict

 vbt Dec 27, 2013
nice, burning rangers should use dsp

 chenke Dec 28, 2013

vbt said:
nice, burning rangers should use dsp


No, it doesnt use SCU DSP...