emulation speed

evildragon · Post by **evildragon** » Wed Mar 21, 2007 6:57 pm

while trying to develop something on the genesis, i noticed a trait, and want to verify it... I am going to use Sonic 2, the Aquatic Ruins level as a demonstration...

KEGA Fusion: At top of the level, jumping around the trees, causes the game to lag greatly.

Sega Genesis with MC68000: This lag does not happen, and if it does, I had to be trying REALLY hard for it to occur..

Sega Genesis with SCN68000: Same as KEGA Fusion..

I have not tried Gens to test this, but do emulators only emulate the poor speed of the Signetics CPU? I will be testing Gens right after this post to see if it occurs too..

evildragon · Post by **evildragon** » Wed Mar 21, 2007 7:04 pm

UPDATE: Gens does it too, it lags with the leaves falling from jumping around the tree..

My way of testing this: Get the blue powerup, and it should flash 60 times a second.. Well, if the leaves are falling, and it lags, the flashing turns to 30 times a second.. But on my MC68000 based Genesis, this does not happen..

Stef · Post by **Stef** » Wed Mar 21, 2007 9:52 pm

It lags on Gens as it lags on Fusion. But i believe that also happen on real hardware (i'll test it). Actually the lags depend a lot from the place you are.

Edit : as expected lags also happen on real hardware (more than emulator in fact). I guess you tested in NTSC mode on emulator where you tested on a PAL megadrive. My megadrive is modded, lags are almost absent in PAL (50 Hz) but really here in NTSC (60 Hz).

You have to know than emulators are generally "optimist". They can be faster than real hardware in some case (due to some missing "wait state" emulation) but they are never slower

evildragon · Post by **evildragon** » Wed Mar 21, 2007 10:06 pm

Stef wrote:It lags on Gens as it lags on Fusion. But i believe that also happen on real hardware (i'll test it). Actually the lags depend a lot from the place you are.

Edit : as expected lags also happen on real hardware (more than emulator in fact). I guess you tested in NTSC mode on emulator where you tested on a PAL megadrive. My megadrive is modded, lags are almost absent in PAL (50 Hz) but really here in NTSC (60 Hz).

You have to know than emulators are generally "optimist". They can be faster than real hardware in some case (due to some missing "wait state" emulation) but they are never slower

i live in america, i only have NTSC stuff..

Here's the thing, I have to Genesis units, one lags, and the other does not lag.. One that DOES lag has the Signetics SCN68000 CPU, and the one that doesn't has the MC68000 CPU.. both systems are not modified in anyway...

I will record a video to show the difference, shortly after I wire it up to the DVD recorder...

evildragon · Post by **evildragon** » Wed Mar 21, 2007 10:36 pm

ok, i recorded the videos, and after i watched them, my Moto one DOES lag, but not as bad.. my signetics one looks like it just wants to die, lol

i'll pass this one off as a "who knows" kinda thing.. we'd need a way to run a benchmark on them (one that works via the Sega Loader, as I don't have an EEPROM)

Stef · Post by **Stef** » Thu Mar 22, 2007 9:01 am

evildragon wrote:ok, i recorded the videos, and after i watched them, my Moto one DOES lag, but not as bad.. my signetics one looks like it just wants to die, lol

i'll pass this one off as a "who knows" kinda thing.. we'd need a way to run a benchmark on them (one that works via the Sega Loader, as I don't have an EEPROM)

You have 2 differents megadrive ? both are ogininals (no clone) ? it's definitly not normal to see some speed difference between your 2 systems.

TmEE co.(TM) · Post by **TmEE co.(TM)** » Thu Mar 22, 2007 10:26 am

I have PAL MD2 (can be NTSC if I flip a switch

) and it is overclockable aswell. Since I'm using PAL, less ints/sec, more time for CPU, none of the games I have lag, even Sonic2 (VERY slightly in dual screen though). Overclocked it doesn't lag at all. There's a HD68C000 CPU inside. My pirate MD with MC68000 didn't lag also. What can I say, OC your genny of switch to PAL.

evildragon · Post by **evildragon** » Thu Mar 22, 2007 3:19 pm

Stef wrote:
evildragon wrote:ok, i recorded the videos, and after i watched them, my Moto one DOES lag, but not as bad.. my signetics one looks like it just wants to die, lol

i'll pass this one off as a "who knows" kinda thing.. we'd need a way to run a benchmark on them (one that works via the Sega Loader, as I don't have an EEPROM)
You have 2 differents megadrive ? both are ogininals (no clone) ? it's definitly not normal to see some speed difference between your 2 systems.

yep, both original, no clones.. Over on the overclocking underground forum, epicenter, the one who found the overclocking on the genesis, says that the SCN68000 used in the early Genesis are ineficient, and run 20% slower, thus why Sega changed it...

Here's videos to show.. notice the one with the MC68000 don't lag as "much".

http://blackevilweredragon.spymac.com/SCN68000.mp4

http://blackevilweredragon.spymac.com/MC68000.mp4

Stef · Post by **Stef** » Fri Mar 23, 2007 8:54 am

evildragon wrote:
Stef wrote:
evildragon wrote:ok, i recorded the videos, and after i watched them, my Moto one DOES lag, but not as bad.. my signetics one looks like it just wants to die, lol

i'll pass this one off as a "who knows" kinda thing.. we'd need a way to run a benchmark on them (one that works via the Sega Loader, as I don't have an EEPROM)
You have 2 differents megadrive ? both are ogininals (no clone) ? it's definitly not normal to see some speed difference between your 2 systems.
yep, both original, no clones.. Over on the overclocking underground forum, epicenter, the one who found the overclocking on the genesis, says that the SCN68000 used in the early Genesis are ineficient, and run 20% slower, thus why Sega changed it...

Here's videos to show.. notice the one with the MC68000 don't lag as "much".

http://blackevilweredragon.spymac.com/SCN68000.mp4

http://blackevilweredragon.spymac.com/MC68000.mp4

Honestly i don't see real differences... if you were able to reproduce the exact movement, i'm sure the slowdowns would have been almost identical.

TmEE co.(TM) · Post by **TmEE co.(TM)** » Fri Mar 23, 2007 10:05 am

evildragon wrote:yep, both original, no clones.. Over on the overclocking underground forum, epicenter, the one who found the overclocking on the genesis, says that the SCN68000 used in the early Genesis are ineficient, and run 20% slower, thus why Sega changed it...

Epicenter said that Signetics CPU sucks, and it won't overclock. He is a damn awesome guy, at the moment, we're kind of doing some FC projects.

BTW, I couldn't watch the videos, what codec did you use ?

evildragon · Post by **evildragon** » Fri Mar 23, 2007 5:12 pm

TmEE co.(TM) wrote:
evildragon wrote:yep, both original, no clones.. Over on the overclocking underground forum, epicenter, the one who found the overclocking on the genesis, says that the SCN68000 used in the early Genesis are ineficient, and run 20% slower, thus why Sega changed it...
Epicenter said that Signetics CPU sucks, and it won't overclock. He is a damn awesome guy, at the moment, we're kind of doing some FC projects.

BTW, I couldn't watch the videos, what codec did you use ?

i used Quicktime 7, MPEG4 (i only have a Macintosh)

evildragon · Post by **evildragon** » Fri Mar 23, 2007 5:12 pm

Stef wrote: Honestly i don't see real differences... if you were able to reproduce the exact movement, i'm sure the slowdowns would have been almost identical.

that's why im gonna try and write a benchmark utility