Overclocking & 68010: Annotated Compatibility List

[SwampFox56]

Received these 5 Minutes ago.
I'd like to give away 3 of these to anybody who wants to try it out for free.

Very cool. The way I got both oscillators into my own, personally Genesis - was by using two switches. One to switch from onboard clock - to oscillator. I then soldered the GND, and Clock pins of both oscillators together, so I only had to have one ground and clock wire. Then the second switch I soldered to the VCC pin separately on each oscillator - which determines which crystal get power thus determining the clock signal.

I like this board much better though...

EDIT:

Oh is this Model 2 compatible?! That makes a world of difference!

[Helder]

It allows you to use a 68k CPU in the PLC form factor which is used on the Model 2 on a Model 1. The size of the dip package CPU on the Model 1 is huge and this is a drop in replacement using pin headers and a smaller form factor CPU and the extra components to take roughly the same space the giant dip package took.

Nice work and design as well as thought went into it, I'd like to see ArcadeTV or someone else showcase it in action.

[MegaDriver]

Something just crossed my mind... This may sound silly, but has anyone tried (just for comparison purposes) how reproduction carts of games on the overclock list perform? Better, worse or simply the same as the official cartridges?

I only have one so far (out run) but I will test it today just to check.

[Barone]

I haven't tested any, but if they're using recently produced ROMs they should perform as the Everdrive MD did. I mean, we shouldn't see problems like the ones found in some of the old copies of Super Hang-On, which seem to be related with ROM access constraints.

[OldSchoolBobby]

(I can finally post here, thanks !)

Hello everyone.

I have a PAL model 1 VA4 (exactly the one referred to in this post).

NB : All of this below comes from memories of 1-2 year(s) ago. I'm pretty sure of it but I could have forgotten things along the way. My apologizes if it happens.

I basically confirms everything already tested on various shoot 'em ups, and can add that...

Alien Soldier forced to PAL 60Hz (accelerated then) mostly works at 12Mhz (graphical glitches can happen against Seven Force Kaede), all on Mega EverDrive [video].

Dune II works fine at 12Mhz, again on Mega EverDrive. I've played hours and hours, with lots of units, up to the end of a campaign. I'm not knowledgeable enough to tell if all slowdown is removed but for sure there's much less than in normal conditions.

Thunder Force IV (tested on Japanese cartridge) has some intentional slowdown which cannot be removed by overclocking (but disappear in higher difficulty modes). I know this is more or less well-known but I've read contradictory things on the subject (so, here's mine based on a solid test at least), and it may be useful to specify in the original post, perhaps.

I also played Herzog Zwei but can't remember well enough the results so... I prefer not tell anything in such case.
I'll be glad to contribute more when I get back to my Mega Drive anyway ! Thanks for this very useful thread.

[Eep386]

I used to own a 68010-fitted Genesis some years back (fitted to an NTSC VA3 Model I no less), and I can remember the results of some of my tests:

Air Diver works on a 68010, but you cannot skip the opening intro otherwise it locks when you start the game. In-game play is noticeably faster and less choppy, also the title screen effects are way faster.

Gain Ground doesn't seem to mind the 68010, until it skips the third time zone entirely! Might be handy for speed-running

Super Hang-On gains a bit of a boost from a 68010 with no visible problems. It tends to speed up around the checkpoint markers and slow back down around the other competitors.

Super Street Fighter 2 locks up on the opening cutscene for Ryu.

Sonic 3 and Sonic and Knuckles also don't care much for the 68010 either, boot-looping at the Sega logo. This is well-known though I think.

[Barone]

It looks like a lot of games would need to be patched to work with the 68010.
Thanks for the input, guys. I'll update the table based on the new info.

[CrossBow]

What is the difference if any between the standard 68k such as the Signetics and Motorola ones vs a Motorola 68000L10? My understanding is that the L10 on the end just means it is rated for 10mhz speed? And according to the spec sheet, the 68000L10 CPU can run as low as 4mhz to the rated 10mhz.

I'm asking because I have an HDG va3 with the Signetics in it. I installed a 64pin socket and have been trying different 68k CPUs in it. However, only the Signetics 68k that came with it originally will work for anything. I am able to at least get Sonic Spinball to load up and sometimes start a game with the 68000L10, but then it will always lock up at some point within. In fact none of the games I've ever tested with a 68000L10 work etc for Gunstar Heroes amazingly. It will start and get about halfway through the first level and then usually lock up in the same place each time.

Point is, I'm trying to find alternative 68ks that could be used in a standard 64pin Dip based Genesis. I even ordered some Hitachi ones with the same exact model numbers as the Hitachi's found in Genesis units and same thing. In fact, I can't get most games to even give me a title screen with these chips in them.

There isn't a real point to any of this other than my own curiosity, but it would appear that the Sega Genesis isn't just using a stock 68k clocked at 7.76 either... Because if that were the case, then any 68k that could handle that clock speed (Nearly all of them), should work as a drop in replacement, but I'm finding this to not be true.

Thoughts on this at all?

[MegaDriver]

@CrossBow:
Sorry, I don't understand what you are trying to achieve.
All I can say is that I once replaced a 68000P8 with a 68000P10 and so far the Megadrive has been working fine.

Returning to the thread topic, I noticed that OutRun has a graphical glitch while playing overclocked. When going through corners a triangular shaped piece of the road appears from either side.
This same glitch seems to occur even at normal clock speed, but it is so reduced that it is almost imperceptible. It appears that overclocking worsens it.

[CrossBow]

@CrossBow:
Sorry, I don't understand what you are trying to achieve.
All I can say is that I once replaced a 68000P8 with a 68000P10 and so far the Megadrive has been working fine.

As I said. mainly just for curiosity sake. I do have a pair of Hitachi P08 chips but neither will work. Granted the Hitachi's came from China...but the two Motorola gold ceramic L10s I have came from a reliable US distributor and were pulls from Classic Macs I believe. The only thing I can figure is that somehow there just isn't that great a contact with these other chips and using my 64pin socket I installed. But I really don't want to desolder the socket and then solder in these chips to find they still won't work right. That is a lot of heat and wear on the pins and chips...hence why I installed the 64pin socket.

[MegaDriver]

But when you put the original Signetics on the 64pin socket you installed, the Genesis works ok with games?

Have you tried putting a regular MC68000P8 just to see what happens?

I am not familiar with the 68000L10, you are certain it is pin-to-pin compatible?

[MegaDriver]

Forgot to mention that I have been playing Undeadline and @10Mhz the game plays faster and I didn't noticed anymore slowdowns!

[CrossBow]

But when you put the original Signetics on the 64pin socket you installed, the Genesis works ok with games?

Have you tried putting a regular MC68000P8 just to see what happens?

I am not familiar with the 68000L10, you are certain it is pin-to-pin compatible?

According to the data sheets, the L10 is pin to pin compatible. As an update, I did go ahead and desolder the socket and solder the L10 straight in. Doing this, I was able to get Dune, Gunstar Hereos, Wardner and a few other games to load up without issue and play. However, none of the sonic games would load up. Sonic 1 and 2 just give me a black screen, blue screen, or corrupted Sega logo with garbled FM tones being generated. Sonic 3 would sometimes start with a corrupted sega logo and then lock up during the intro at fairly random places. Even now with the signetics Sonic 3 is iffy from time to time though everything else I pop in seems to work fine. No idea really... I have another HDG va6 model that isn't molested so if this one continues to be too much of a problem child then I will swap them out.

So little more testing involving Sonic 3 and it appears that only Sonic 3 has issues with my genesis. Turns out that if I play another sonic game that runs just fine, or most any other game really, and then plug sonic 3 in, it will start up and play fine? Beginning to wonder if the issue is my sonic 3 cart.

[Peeteris]

Sega Mega Drive (EU), VA6.5/8, region set to North America - NTSC, Motorola 68000, overclocked to 10MHz.
5 min - Psycho Pinball - title screen music sounds terrible.
30 min - Sonic 3 & Knuckles - no crashes, but graphical glitches between water and ground (white dots following between ground and water until entire screen is only water or ground), no ice cap music problems found.
10 min - Vectorman 1 and Vectorman 2 - no problems found at all, smoother gameplay.
5 min - Ristar - slowdowns not present in intro sequence anymore.
Completed game - Streets of Rage 3 (JAP, translation) - no problems found.

P.S. I found out that Sonic 3 isn't the only game with graphical glitches between water and ground. I found this in Ristar and some other games I can't remember. Probably every game with water like in these games is affected. So as far as I understand, there are graphical glitches (vertical pixelation) between color palete swaps. Correct me, if I'm wrong, as I'm not really sure, what's going on.

[ironnick23]

Something just crossed my mind... This may sound silly, but has anyone tried (just for comparison purposes) how reproduction carts of games on the overclock list perform? Better, worse or simply the same as the official cartridges?

I only have one so far (out run) but I will test it today just to check.

Tested a bootleg of Eliminate Down (blank uk shell) with the 10mhz overclock VA3. It plays but without sound. There is a simple glue chip inside the cart. I referenced this chart to see if this was the case with a legit cart (which its not).

Also sidenote, Ren & Stimpy: Stimpy's Invention plays fine and has no effect with a 10mhz overclock.