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Overclocking Your Sega Genesis/MegaDrive

Posted by simoniker on from the sonic-go-faster dept.

Deven "Epicenter" Gallo writes "I've recently been working on a project to alleviate the slowdown inherent in older game systems. How you ask? By overclocking them! I've managed to perfect overclocking the Sega Genesis / MegaDrive. The processor (a Motorola 68000, running at a stock speed of 7.6 MHz) can be pushed to 16.0 MHz in my experience, and I am still working on higher. The machine doesn't overheat and is entirely stable at these higher speeds."

28 of 372 comments (clear)

  1. I already have a hard enough time... by tsunamifirestorm · · Score: 4, Funny

    keeping up with Sonic ;)

    1. Re:I already have a hard enough time... by Cornelius+the+Great · · Score: 5, Informative

      "That may be justification alone for why the systems were underclocked at the factory. The clock in many games is based not on an actual clock but the speed of the processor... speed things up and you speed everything in the game up, and that's not very playable."

      You're right. Even on newer consoles, like the Xbox, a 1.4 ghz cpu and 128 mb ram upgrade tends to have problems in certain games. Most console games, unlike their PC counterparts, run proportional to the CPU clock for actual game speed.

      In a PC, overclocking the CPU will usually increase frame rate in newer games. Consoles, with their unified architecture, begin to run into compatibility problems when you make certain components run faster, or will usually speed up gameplay proportionally to the clock speed increase.

      Yes, the above applies to the PC-like xbox too, but not to every game. From what I've been told, running Halo co-op splitscreen on that 1.4ghz xbox runs as smooth as silk.

      --
      Sigs are for losers
    2. Re:I already have a hard enough time... by LocalH · · Score: 5, Informative

      The center of your mindset should rest on the vertical blank - that's your 'unit of time', unless you're doing some splitscreen stuff (like the water effect in Sonic), then you utilize the horizontal IRQ (I also call it a line IRQ) to get there. No busywaiting necessary. Frame rate is mostly constant on the classic consoles, in the sense that it's mostly synched with the refresh rate.

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      FC Closer
    3. Re:I already have a hard enough time... by Spy+Hunter · · Score: 5, Informative

      His site explains that the games don't, in fact, run faster. Most Genesis games must actually be based on a clock instead of the processor speed. The only effect of the overclocking is that slowdown is eliminated. Don't you remember in Sonic games how if you had more than 20 or so rings and you got hit, the Genesis would slow to a crawl as it drew all the rings bouncing around on the screen? In two-player mode slowdown was even more common. Well if you overclock your Genesis, that can apparently be fixed.

      --
      main(c,r){for(r=32;r;) printf(++c>31?c=!r--,"\n":c<r?" ":~c&r?" `":" #");}
    4. Re:I already have a hard enough time... by zeno_2 · · Score: 4, Interesting

      I used to work the help desk at microsoft. (Ok, it was another company, I was never employed by microsoft, thank god.). Anyway, there was this problem when Links 2003 came out, with pretty much any Dell laptop. The problem was, the golfer would swing about 10x fast as normal. After infestigating the problem, we found out that these specific dell laptops would not keep track of windows uptime correctly. We would reboot the laptop, and bring up a program that showed windows uptime, and it would give us completely wrong times. As an example, we would reboot, and the dell laptop would show 48 days uptime. Now, as a "microsoft employee", we didn't have a lot do to, when it came to fixing that particular problem. (it only happened on dell laptops, and we could use windows to verify the uptime was not being recorded correctly. Links 2003 would use that uptime figure to calculate how fast the golfer should swing). In any caes, I was never able to get a straight answer from either Microsoft or Dell as to why the newer dell laptops would not keep the Windows uptime correctly. It was kinda one of those issues that was swept under the rug. So, I can atest to the games out there that use the system clock as a timer to find out how fast to play certain things (probably mainly with animation). This is probably something that is used quite often, especially in a situation (like the xbox)where every system is the same. Oh ya, and I hope the Xbox dies a miserable death.

  2. That does it... by SteveTheRed · · Score: 4, Funny

    I'm going to overclock my Timex Sinclair!!!

    --

    I, for one, welcome our new robot overlords
  3. This is about as interesting by Anonymous Coward · · Score: 5, Funny

    ... as the time I slapped a Type-R sticker on my Casio FX-1000 solar-powered calculator. Before I did that, it took 950 milliseconds to calculate 69! Afterward, it calculated 69! in 940 milliseconds flat.

    Or, wait, maybe it was because the sun came out.

    1. Re:This is about as interesting by toddestan · · Score: 4, Interesting

      The factorial function is about the most intensive thing you can do on a little scientific calculator. 69! is ~1.711E98, which is the largest most calculators can go, as 70! factorial has an exponent of over 100. Unless your calculator can handle 3 digit exponents, then you can compute 449!

      Ahh... the memories... back in middle school we used to glitch our solar powered calculators by doing 69! then covering the solar cells, which sometimes resulted in some pretty weird stuff (we could make TI-30's go into some kind of octal mode, also the calculator could sometimes go into some kind of trippy looped animation on the display, or it could change layouts to another TI model, like the TI-30STAT).

      To bring things kind of back on topic, I once overclocked my TI-85. And some of the games did break, though the good ASM programmers didn't rely on the CPU speed, as it would slow down as the batteries wore out, even if you didn't overclock.

  4. Hmmm.. by LordK3nn3th · · Score: 5, Interesting

    If you can overclock it so much with a noticeable performance, then why didn't Sega set it like that already, if it's so stable? Certainly it would have given them an edge...

    Pushing a 7.6 --> 16MHz is over 100% more than the original! I have yet to see most people get anywhere near that on normal processors.

    --

    ---
    Never criticize religion on Slashdot. You will be modded down for "Troll" no matter how factual it is.
    1. Re:Hmmm.. by BW_Nuprin · · Score: 5, Interesting

      Its possible that later production Gennys had better processors that were clocked down to maintain the same speed as the older models. In the five or so years that Genny was around, I'd expect that there were many many improvements to the 68000. I'd wager that the last couple Gennys off the line could be overclocked three or four times over without a sweat.

    2. Re:Hmmm.. by Arker · · Score: 4, Insightful

      That's the point. The article apparently claims that it remained stable at over an additional 100%. Now, not all processors are alike, but if one of those can handle up to that, shouldn't others be able to handle a fairly good amount of overclocking as well?

      Well you've got to remember that these things were made for several years. Just a guess, but I'm thinking by the time the last ones they sold were made, Motorola probably had long since quit making 7.6mghz chips, and were just shipping whatever their bottom of the line was at the moment and underclocking it.

      Also, you have to remember even if that's not the case, there's a lot of variability in chips. Just because this guy got his to run at this speed reliably, doesn't mean they all would.

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  5. Check results first? by BW_Nuprin · · Score: 5, Insightful

    I don't recall exactly, but I think you could 'overclock' the genesis in older emulators like Genecyst, so perhaps that would be a good way to check to see how well games run overclocked before you actually futz with your real Genny. I would think that many games would have timing problems at a speed greater than stock, particularly those that use raster effects. I can't say for certain, but I know my old Gameboy Color raster effects would break completely if I overclocked them. I would wager that racing games would probably suffer the worst.

  6. sega genesis by Coneasfast · · Score: 5, Informative

    for those of you who don't know, 'genesis' is the north american term whilst 'mega drive' is the UK (and european?) term

    here are the specs and some history

    --
    Marge, get me your address book, 4 beers, and my conversation hat.
    1. Re:sega genesis by IntergalacticWalrus · · Score: 5, Informative

      In fact "Mega Drive" is the original japanese name too. That stupid "Genesis" name was in north america only.

  7. Videos.. 26 meg? by E1ven · · Score: 4, Informative

    The site, including the videos, are convieniently mirrored to sq7.org

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    Colin Davis
  8. 16mhz is fast! by Snagle · · Score: 5, Funny

    16mhz is what the Palm Zire runs at too. That means if someone ports Palm OS 4.1 and you attach a VGA/LCD thingy you can have a Sega brand PDA. True, you are sacrificing portability, but hey, I think there are some kids at my school with pockets big enough for a Genesis.

  9. Re:Correct me if I'm wrong... by YOU+LIKEWISE+FAIL+IT · · Score: 4, Interesting
    But since games that can't run well on a console platform simply aren't published for that platform, isn't this somewhat useless?

    There isn't enough correction in the world. A lot of games get released for consoles with noticable periodic slowdown - the classic example is the Metal Slug series. Still happening today too, I notice the occasional wad of dropped frames playing my XBox or Gamecube.

    --
    One god, one market, one truth, one consumer.
  10. Poor Server by General+Sherman · · Score: 4, Funny

    It's a shame he didn't overclock his server to twice it's original speed. Those 10-25MB .avi's really don't help.

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    - Sherman
  11. An easier way... by wardomon · · Score: 4, Funny

    Plug it into the 220 outlet behind the stove. It'll run really fast for a couple of seconds and then you can get on with your life.

    --

    - - - If the sun is a star, why can't I see it at night?
  12. Re:And this is good? by ...+James+... · · Score: 5, Interesting

    You'd think it would be most, but that doesn't appear to be the case:

    I've written my own Nintendo Emulator. Just modified it to execute 5000 CPU instructions per scanline instead of the typical 114. Fired up Super Mario Brothers, Contra, and a few other games and they all appear to work fine.

    I suspect (and I would've thought otherwise before this test) that many games are sychronized with the v blank interval or interrupts. I haven't tested sound, however, since I haven't written that part of the emulator yet.

    --
    get nemulator
  13. How does it work with other genesis attachments? by Recovery1 · · Score: 4, Interesting

    Now here's an interesting thought. What would happen if you hooked one of these overclocked Genesis into the Sega CD or 32X attachments? As I recall the whole process of getting the Genesis and Sega CD to work together in parallel was a challenge to begin with because of different clock speeds between the two CPUs in each device.

    My guess is he hasn't tried it or it doesn't work, as he doesn't elaborate on it.

  14. Sega slowdown... by Anubis333 · · Score: 5, Informative

    Slowdown is an integral part of older consoles. Modern day emulators that can easily push these consoles with no slowdown at 60FPS impliment a technique to fake "slowdown." It's a lot easier to just grab a genesis emulator for your Dreamcast or Xbox than attempt a hardware mod like this.

  15. Famous last words... by djupedal · · Score: 4, Funny

    The machine doesn't overheat and is entirely stable at these higher speeds.

    The machine doesn't overheat and is entirely stable...

    The machine doesn't overheat ...

    The machine doesn't ... ...work ?

  16. Any way to get homebrews on real hardware? by Kris_J · · Score: 4, Interesting
    Overclocking an; Atari 2600, Atari 7800, Gameboy, GBA, C64 (or any system with a disk drive option) or even a PSX/PS2 is really cool because you can get homebrew code onto real hardware with some sort of RAM or flash cart, or writable media. Enthusiasts can subsequently write new programs that use the extra clock cycles. However, I don't know of any way to get ROMs onto a Genesis/Mega Drive -- is there one?

    Meanwhile, anyone in the Perth area that wants a Mega Drive to try this on, you can have one of mine if you'll convert a second for me.

  17. You know... by TWX · · Score: 4, Funny

    " ... as the time I slapped a Type-R sticker on my Casio FX-1000 solar-powered calculator. Before I did that, it took 950 milliseconds to calculate 69! Afterward, it calculated 69! in 940 milliseconds flat."

    Personally, I prefer my sixty-nine bangs to take a little longer than that...

    --
    Do not look into laser with remaining eye.
  18. Re:- Overclocking DOES NOT cause games to speed up by LoadWB · · Score: 5, Insightful

    I am glad to see this as a root post. Anyone who has ever dug into the internals of the Amiga, Mac, or Atari ST hardware has found that moving to faster 680x0 CPUs did not affect game speed, only the amount of lag (we called it "bog") in a game.

    I have nearly two decades of experience with the 680x0 CPUs in the Amiga systems. I remember being absolutely thrilled when Sega used the 68000 CPU in the Genesis. I hacked an original unit which had the 68-pin package with a 68010. Honestly, I do not remember the full results, but I recall I was still able to play the majority of my collection (two carts at the time, hahahaha.)

    I also toyed with the idea to replace the 68000 with an MTec 68020 accelerator pulled from my Amiga 500. I never tried it, and I still am not so sure it would have worked anyway. If the AmigaOS was a little less hard-wired to the Amiga hardware architecture, given a little work, we might could have seen AmigaOS running on a Genny ;) Hell, we might still be able to see that just for kicks.

    Having gone from 68000 to 68040 in all its discernable steps (I still dream of a 68060/PPC accelerator for my A4000,) I have been able to bring all of my games with me. The only problem I have is with expected timing of the OCS chipset versus the AGA chipset. But there are a number of great hard drive installers which over come this, as well as system "degraders" which place the computer in a state almost identical to the original Amiga hardware.

    In any case, I'm inspired by this article and look forward to dropping a 12MHz clock generator in my Sega II (provided its CPU will support it.)

    (climbing up on soap box) It is also worth mentioning that us old-hat gamers take a lot of shit for being so nostalgic and blah blah blah, aching for an era long-past. I got news for those who cast stones, many of those games were FUN, and down-right phuqn great. I will not say that none of my collections are nostalgic -- I have a number of Atari 2600 carts which I never played then and do not play now other than for testing, simply because they are Atari. But the majority of the games I collect (Amiga, Atari, Sega, NES, TI, C64, and others) WERE fun, and are STILL FUN.

    How many people are still playing a "dead" console because the games rocked and you cannot get them for "modern" consoles? PS1 is almost 10 years old, and yet it still has a large following. I bet in 10 years there will still be a large faction of people playing the original XBox because some of the titles will not be available on newer consoles, or just will not play the same. (I do wonder how game play of XBox 1 games will be on the XBox 2...)

    Well, enough of that.

    END OF LINE

  19. No... by hyc · · Score: 4, Informative

    You're off by at least a decade. Maybe the original Pong and Atari 2600 were cycle-counters. Everything made after that used VBI timing. Newer arcade boxes like the NeoGeo used 68020s, which of course had instruction caches that made cycle-counting impossible.

    I'd love to get an Atari ST emulator up and running Spectrum Holobyte's Falcon, overclocked. It would be cool to see it running at a smooth frame rate.

    As I recall, by the end of life the Motorola 68000s were all made as 16MHz parts. The slower parts were simply not made or sold any more. Also, even when they were genuine 8MHz parts, they were pretty reliable with 50% overclocking; we did this sort of thing all the time in Atari STs before the 68020 and 68030 upgrades got popular.

    There were limits to what you could gain though, since the 68000 had no on-chip caches of any kind and the system bus generally couldn't handle as much of a speedup. The better upgrades included a memory cache with the accelerated 68000 on a daughterboard that plugged into the original CPU socket, to allow the processor to run at full speed without disturbing the rest of the system. It was all a dicey job though; the tolerances in the rest of the system were pretty ragged. I remember having to desolder a bunch of 74LS series buffers and replace with 74HC or AS series or somesuch that worked at faster clock rates, more noise immunity, etc., adding tantalum capacitors everywhere, etc... Ah, the good old days.

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    -- *My* journal is more interesting than *yours*...
  20. Nintendo did this... by Chordonblue · · Score: 4, Informative

    A lot of SNES stuff had 'assist' chips in the cartridges. Most were basic 'blitter' chips, but there were some that actually had co-processing on board for 3D graphics (SuperFX). Games like Starfox and Stunt Race FX simply would not have been possible on that console otherwise.

    I wonder if you're thinking of a special version of Ecco that ran on the 32X Genesis co-processor.

    --
    "...Well, there's egg and bacon; egg sausage and bacon; egg and spam; egg bacon and spam; egg bacon sausage and spam..."