[Ravenfreak]

This is something I've been pondering since I first got this game a few months back. I've first played Earthworm Jim in my Model 1 Genesis, and noticed the game lags and even hangs up sometimes at the beginning of New Junk City. So I played it on the Model 2 Genesis I gave my girlfriend, and not once did it lag or freeze. Any particular reason why? BTW this is the only game I own that does this, all my other games play just fine on my model 1 Genesis.

[SoullessSentinel]

Some versions of the Model 1 megadrive use a different brand of 68000 cpu (Signetics) than others, these systems cannot be overclocked sucessfully, and most likely have other issues too. This is the only reason I can think of to why a game would lag only on a Model 1, unless any of the hardware guru's here have a better explaination.

[MarkeyJester]

I ran a google search and it seems that "some" megadrives might contain a different processor "MC68SEC000", possibly the Megadrive 2's, it was apparently a low cost downgraded version of MC68000, but functioned more or less the same for megadrive games (considering megadrive games don't appear to use ALL MC68000 instructions that the MC68SEC000 may not have).

So yeah, it might be as lukeusher123 said.

[GerbilSoft]

All Mega Drives have a 68000 rated for 8 MHz operation. Whether a given CPU can be overclocked or not has nothing to do with the CPU's operation at the standard 7.61/7.67 MHz clock rate.

My best guess would be memory latency. Sega probably used faster memory in later models.

This post has been edited by GerbilSoft: 11 November 2010 - 02:22 PM

[doc eggfan]

Aren't the sprites in EWJ compressed? So the lag would possibly be due to decompressing the sprites?

Is there a similar issue with Aladdin, or EWJ2?

[Billy]

Could this possibly also affect the Sega CD version of EWJ?

[TmEE]

Get rubbing alcohol and give your games and cartslots a good clean. Don't forget pencil eraser, it does wonders with dirty carts. Usually such problems happen with 32X with loose ribbons, but they can happen without 32X aswell, though very rare as game should just outright crash on any problem.

[DigitalDuck]

Get rubbing alcohol and give your games and cartslots a good clean. Don't forget pencil eraser, it does wonders with dirty carts.

Alcohol and rubbers. Sounds like a normal night out.

[TmEE]

Get rubbing alcohol and give your games and cartslots a good clean. Don't forget pencil eraser, it does wonders with dirty carts.

Alcohol and rubbers. Sounds like a normal night out.

hahahaha

[Jaseman]

I have both my Model 2 and my Model 1 set up. I must find an EWJ cart and try this out, for great justice!

[TomoAlien]

Some versions of the Model 1 megadrive use a different brand of 68000 cpu (Signetics) than others, these systems cannot be overclocked sucessfully, and most likely have other issues too. This is the only reason I can think of to why a game would lag only on a Model 1, unless any of the hardware guru's here have a better explaination.

Quite possibly this. Slight differences between hardware can lead to bad things and well... PS2 has some slowdown problems with some of the PS1 games even though it has the PS1 hardware in it. I've heard that Gradius Gaiden's 7th stage has a slowdown on PS2 that makes it nigh-impossible to play, but there aren't any videos on it, though.

Hmm... Could you record how the glitch looks? I am interested in such things.

[TmEE]

The Signetics CPU stuff is all lies. You can put a Signetics into a VA6 and it will nicely overclock to 12MHz, even 14MHz but lot of games get glitchy then (and they would with Motorola or Hitachi CPU too).

[Ravenfreak]

So I recently bought Jurassic Park and Jurassic Park Rampage Edition, both use the GEMS sound driver, and they lag too. Spinball also lags... so is it possible that GEMS uses more processing power than SMPS?

[Andlabs]

...that's really odd, since GEMS mostly runs in the Z80 with very little 68000 interaction — there are a few "mailboxes" that you can set to change what the music does. I wonder how GEMS's 68000 routines could cause lag...

[TmEE]

I'm more willing to believe some resistor is loose or wrong in that MD, causing some open drain bus control signal rise too slowly, thus potentially causing such issues... I really want to see inside that MD...