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Classic Games (Games) Entertainment Games Hardware

Overclocking Your Sega Genesis/MegaDrive 372

Posted by simoniker 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."
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Overclocking Your Sega Genesis/MegaDrive More

Overclocking Your Sega Genesis/MegaDrive

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  • I already have a hard enough time... (Score:4, Funny)

    by tsunamifirestorm ( 729508 ) on Wednesday March 10, 2004 @11:51PM (#8529055) Homepage
    keeping up with Sonic ;)
    • The question is, can you overclock Dr. Robotnik?
    • Now its super sonic the hedgehog.

    • Re:I already have a hard enough time... (Score:4, Interesting)

      by LostCluster ( 625375 ) * on Thursday March 11, 2004 @12:11AM (#8529182)
      keeping up with Sonic ;)

      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.

      Unless somebody's found a way to get this thing to run Linux and other non-cartrige programs, this isn't going to be very useful.

      • 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.

        Err, you might be right about programmer's being relatively lazyish (/efficient) and relying on the processor speed for timing...but they could always easily slow down a game that was too fast, but not the opposite.

        Actually...programers don't JUST

        • Re:I already have a hard enough time... (Score:4, Informative)

          by Monkelectric ( 546685 ) <slashdot@NOSpam.monkelectric.com> on Thursday March 11, 2004 @12:40AM (#8529318)
          i'd be surprised if even sega games were so poorly programmed that they depended on the hardware clock speed. Generally what one does is define a unit of time (actual time, clock ticks, cycles, etc -- doesn't matter as long as its uniform), then you define all the motion/game logic as functions of a time delta (time elapsed between the last frame and this current one), since the frame rate is never constant. This way, things happen at a constant rate regardless of frame rate.

          That being said, ive never done any console programming, so who knows :)

      • Re:I already have a hard enough time... (Score:5, Informative)

        by Cornelius the Great ( 555189 ) on Thursday March 11, 2004 @12:38AM (#8529308)
        "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 [gamestron.com] 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.
        • On a PC, there's usually a "system time" that can be accessed by a program to keep the in-game timing in line with real time, but most consoles have no system clock and therefore no need to keep track of time relative to real time, so they don't have any timer to count against.

          Anybody know what the status of this on the current consoles? I guess the XBox might be close enough to a PC to keep a clock, but I don't see why any of the other consoles would go out of their way to do that.
          • You're confusing the concept of time with time...bear with me :) Consoles don't know the time of day. They simply need a high resolution TIMER so they know how much time has elapsed, console doesn't care if its 1904 or 2004, it just cares how much time has elapsed since it generated its last frame.

            That being said, the XBOX, PS2, and GameCube will all allow you to set the system time in their OS.

          • Almost every computer-like machine in existance has a clock in it. This clock isn't necessarily a clock like you'd use for viewing the current date/time, but is in some cases internal to the CPU.

            What units this clock runs in varies from chip to chip, but most of the time, the OS that you're using provides you with a decent way of using it, in some sort of standard measure of time (vxWorks with the BSPs that I've used, for example, provides you with 60ths of a second, which is very convenient).

            This is ve

          • Re:I already have a hard enough time... (Score:5, Interesting)

            by zeno_2 ( 518291 ) on Thursday March 11, 2004 @03:25AM (#8529947)
            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.

      • Re:I already have a hard enough time... (Score:5, Informative)

        by Spy Hunter ( 317220 ) on Thursday March 11, 2004 @12:54AM (#8529381) Journal
        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.

        • You can often "overclock" emulators too. Many have a setting somewhere that say something like "instructions per scanline" or "percent of instructrions to execute". Just increase that number and you have an instantly faster (emulated) processor.

      • 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.

        The CPU speed is usually NOT used for game timing in cases like this (well, in older NES games it was, but usually not for the faster systems). The main source of timing in video games is the video refresh which, on game consoles, is always 60Hz. Increasing the clock speed simply allows the game to get more work done during each fram


      • Remembering back to my demo coding days (on various Acorn/ARM systems) the reason the game doesn't scream along at some insane rate when the machine is clocked higher is because the update of the framebuffer is synchronised with the v-sync of the display, which on TVs / non multisync monitors was either 50Hz or 60Hz depending on where in the world you bought your equipment.

        If the machine is clocked higher, the only difference is that more code can execute between v-syncs, so the game appears not to slow do

  • That does it... (Score:4, Funny)

    by SteveTheRed ( 244567 ) on Wednesday March 10, 2004 @11:52PM (#8529056) Homepage
    I'm going to overclock my Timex Sinclair!!!

    • Re:That does it... (Score:2, Interesting)

      by fpga_guy ( 753888 )
      Or better still, build a Timex/Spectrum in an FPGA [sourceforge.net] and clock it as fast as you like...

    • Re:That does it... (Score:3, Interesting)

      by Kazymyr ( 190114 )
      I know the parent is supposed to be funny - but I did have my Sinclair ZX Spectrum overclocked to 6 MHz (from the original 3.5). Some games would run, some not. The clock speed could be changed on-the-fly without any ill effects. Of course at 6 MHz the cassette load/save routines were totally off, so that for loading commercial programs I needed to switch it back to the original speed. But files saved at 6 MHz would load back perfectly fine at 6 MHz. Loading/saving was quicker, too (higher pitch of the carr

  • This is about as interesting (Score:5, Funny)

    by Anonymous Coward on Wednesday March 10, 2004 @11:52PM (#8529063)
    ... 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.

    • You know... (Score:5, Funny)

      by TWX ( 665546 ) on Thursday March 11, 2004 @01:27AM (#8529534)
      " ... 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...

  • And this is good? (Score:2, Redundant)

    by djocyko ( 214429 )
    I wonder how many games out there assumed they were running on a 7.6MHz machine and now run too fast...

    • Most of them... (Score:3, Informative)

      by LucidityZero ( 602202 )
      Most (if not all) of them, I'd assume.

      When you're developing a game for a specific platform that will never change, why would developers use any sort of time-based algorithm to determine game speed? You'd end up with a smoother/prettier game if you merely used the limits of the hardware to control the speed of your game.

      Especially back in those days where most of the games really DID push the limits of the hardware. Almost any game would slow down with too many sprites on the screen, etc.

      I'd assume al

      • Re:Most of them... (Score:3, Informative)

        by LocalH ( 28506 )
        If the game just updates the screen whenever the hell it feels like it, busywaiting until it's time, then yeah, it'll fuck up. But any properly coded game will utilize the VINT to synch to the refresh rate. Sonic 2 does this for sure, you can even see the garbage in the bottom border where the game is initializing the VDP for the next frame.
      • Most of them are timed based on the video signal. Depending on how well they were coded, they may will run at normal speed, just with fewer dropped frames when the sprites pile up.

    • Re:And this is good? (Score:5, Interesting)

      by ... James ... ( 33917 ) on Thursday March 11, 2004 @12:14AM (#8529198)
      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.
      • oh yeah, and I know that NES != Genesis, but for the purposes of this discussion, it's probably safe to assume that similar techniques would've been used when developing for either platform.

      • Re:And this is good? (Score:3, Informative)

        by Pr0xY ( 526811 )
        I've also mad a NES emualtor before, and there is a reason the games arent running any faster.

        firstly, many of the games wait for an event (such as the vblank to occur), or sit in an infinite loop waiting for an NMI to process the next frames work.

        Firstly, as you probably know, NES games tend to be very timming critical. Switch to a game that does any cycle counting to determine with things should happen (just about anything made by RaRE should do) and it'll be all fscked up :)

        And as for the speed itsel
    • The article seems to imply that Sonic 2 was the only game checked, and that it was fine in normal play but glitched in the 3D half-pipe bonus levels...

  • Hmmm.. (Score:5, Interesting)

    by LordK3nn3th ( 715352 ) on Wednesday March 10, 2004 @11:53PM (#8529073)
    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.
    • Not if they are unclocked to begin with. Those processors ran at 16MHz on Macs without any problems.

    • Re:Hmmm.. (Score:3, Insightful)

      by jaxdahl ( 227487 )
      Reliability.

      You don't want to have to replace thousands of pricey (back then) consoles if chips prematurely fail.

    • Re:Hmmm.. (Score:5, Interesting)

      by BW_Nuprin ( 633386 ) on Thursday March 11, 2004 @12:01AM (#8529136)
      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.
    • Because games were depending on the clock speed to be equal on all of the consoles, for any clocks within the game or other time-based things. What likely happened was during the life of the console, the original chip got discontinued so later units just underclocked the successor chip to be close enough.
    • Side note;

      Closest thing I've seen in normal procs are the old-fashioned Durons. They approached that mark.

      I had mine, a 600 Mhz proc, running at 900 Mhz with no problems for a few years with a cheap heatsink/fan.

      Clocked it down to 850 Mhz after I moved and it started failing (probably ventilation issues). Still survived until I got a free Thunderbird to replace it with.

      Still, 3 years at 150% is a pretty good run for a normal proc, and it probably still runs.

      The point is that high-overclock potential is

  • Now what about other consoles? (Score:3, Funny)

    by SDMX ( 668380 ) on Wednesday March 10, 2004 @11:53PM (#8529074)
    Someone needs to recreate this with a NeoGeo. Metal Slug needs to be played free of all that ridiculous slowdown. =]

  • Check results first? (Score:5, Insightful)

    by BW_Nuprin ( 633386 ) on Wednesday March 10, 2004 @11:54PM (#8529078)
    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.

  • Correct me if I'm wrong... (Score:4, Insightful)

    by kundor ( 757951 ) <kundor@memBALDWI ... org minus author> on Wednesday March 10, 2004 @11:54PM (#8529084) Homepage
    But since games that can't run well on a console platform simply aren't published for that platform, isn't this somewhat useless?

    Granted, it's nice for the coolness factor, but unlike PCs, newer and flashier games only come out for beefier platforms and can't be run on the old ones anyway, no matter how fast they're going.

    • Sonic the hedgehog 2 had some moderate to major slowdown in some areas - I remember dying several times because of lag in a sonic game.

      God that sounds like my latest experiences with online FPSs: "LAG!!!! I totally hit you head on with the redeemer!"

    • Re:Correct me if I'm wrong... (Score:5, Interesting)

      by YOU LIKEWISE FAIL IT ( 651184 ) on Thursday March 11, 2004 @12:03AM (#8529143) Homepage Journal
      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.

  • Boy do I remember the slowdowns (Score:4, Interesting)

    by General Sherman ( 614373 ) on Wednesday March 10, 2004 @11:54PM (#8529087) Journal
    Whenever I would play Road Rash 2 in split screen mode, the Genesis was noticeably slower. I was always disappointed with this, shame I don't have it anymore.

  • Wow (Score:2)

    by Talez ( 468021 )
    I'm suprised games didn't start running twice as fast. Most developers back then would have still been counting clocks.

    • No... (Score:4, Informative)

      by hyc ( 241590 ) on Thursday March 11, 2004 @02:52AM (#8529845) Homepage Journal
      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.

  • As cool as overclocking genesis may seem, this is a decade late.

    Now... if you can overclock today's PC to twice the ghz with no special hardware... then you're talking.

  • sega genesis (Score:5, Informative)

    by Coneasfast ( 690509 ) on Wednesday March 10, 2004 @11:56PM (#8529101)
    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 [retrofaction.com]

  • Comment removed (Score:5, Informative)

    by account_deleted ( 4530225 ) * on Wednesday March 10, 2004 @11:57PM (#8529109)
    Comment removed based on user account deletion

  • 16mhz is fast! (Score:5, Funny)

    by Snagle ( 644973 ) on Wednesday March 10, 2004 @11:57PM (#8529110)
    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.

  • FPS? (Score:4, Funny)

    by red_dragon ( 1761 ) on Thursday March 11, 2004 @12:00AM (#8529131) Homepage

    So now kids will start bragging about how many frames per second they get on Flashback, eh? That's just what we needed right there.

  • anyone want to place a bet.... (Score:3, Funny)

    by npistentis ( 694431 ) on Thursday March 11, 2004 @12:00AM (#8529132)
    as to how high his cute little hit counter registers before his server reaches critical mass? maybe he should've turbocharged that machine first...

  • They knew it all along (Score:3, Funny)

    by Space Coyote ( 413320 ) on Thursday March 11, 2004 @12:01AM (#8529135) Homepage
    It's obvious that this could be done, after all the Genesis has Blast Processing

  • Poor Server (Score:5, Funny)

    by General Sherman ( 614373 ) on Thursday March 11, 2004 @12:04AM (#8529147) Journal
    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.

  • An easier way... (Score:4, Funny)

    by wardomon ( 213812 ) on Thursday March 11, 2004 @12:14AM (#8529195)
    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.

  • How does it work with other genesis attachments? (Score:4, Interesting)

    by Recovery1 ( 217499 ) on Thursday March 11, 2004 @12:18AM (#8529219) Homepage
    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.
    • It works great .. only thing is, DO NOT boot the Sega/Mega CD over 12 MHz or it will get panicky. The best method is to boot at 7.6, run the game. Then once at the title screen halt and go to the higher speed. The 32x works great in my experience as it doesn't rely on the 68000 much .. it uses a pair of its own SH-2 chips.

  • Sega slowdown... (Score:5, Informative)

    by Anubis333 ( 103791 ) on Thursday March 11, 2004 @12:18AM (#8529226) Homepage
    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 [dcemulation.com] or Xbox [xbox-emulation.co.uk] than attempt a hardware mod like this.

  • 3D Graphics on a TI-85 (Score:3, Interesting)

    by KalvinB ( 205500 ) on Thursday March 11, 2004 @12:21AM (#8529235) Homepage
    While in High School I was always coding various things in BASIC on it and one day when I demonstrating how to map 3D objects by placing the sonic sensor on an overhead cart and rolling it under light fixtures, this kid in my calc class goes "you expect that thing to act like a Pentium." I used TI-BASIC to learn how to do 2D translation and rotation and touched on some 3D. I made the first and possibly only graphical adventure game for it complete with text entry and a cursor to click on objects.

    A few years ago I gave it to a friend who needed a TI but I'm pretty sure the Intel Inside Pentium MMX sticker is still on the back of it.

    Ben

  • Great, it's in English... (Score:3, Informative)

    by SavannahLion ( 701337 ) on Thursday March 11, 2004 @12:25AM (#8529252) Homepage
    I've had a cached URL [vuni.ne.jp] to overclocking your Genesis/Mega Drive for a long time. Unfortunately, it's in Japanese and Babel Fish makes it really tough to understand technical instructions.

    I wonder if the author of the article at Epic Gaming read the Japanese article and got the idea from there?

  • Famous last words... (Score:5, Funny)

    by djupedal ( 584558 ) on Thursday March 11, 2004 @12:31AM (#8529276)
    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 ?
  • i remembered having massive slowdowns in streetfighter - especially if you're using guile and execute any combo more than 4 hits

    my favorite combo... but lags in SNES...
    jumping fierce + close fierce uppercut + sonic boom + referse fierce + sonic boom.

    ironically this was under SF2 TURBO

  • We can't let the Sega fanboys beat us. (Score:4, Funny)

    by Maul ( 83993 ) on Thursday March 11, 2004 @12:44AM (#8529334) Journal
    Finally, we can recreate the glorious console wars of the 16-bit era!

    I'm going to overclock my Super NES.

    I'm not going to let those Sega fanboys get the upper hand on this. They already taunted us SNES owners about their "blast processing" in the early 90s.
    • Heh, sorry to burst your bubble, but even at higher clockrates the SNES can't outperform the MegaDrive/Genesis. Too inefficient. Let's call it the 16-bit intel/amd war. ;) But I am working on SNES overclocking. It'll take time, but it's the same basic procedure as with the NES ..
      • Oh gods, I'm having bad flashbacks.

        Ok, short version:

        SNES - slow as hell processor, makes up for it with specialized GFX and Sound chips.

        Genny - Faster processor, better memory usage, but fewer colors onscreen and no built-in scaling and rotation.

        But really, if you aren't running NeoGeo, you're eating squirrel burgers. ;-)

  • Any way to get homebrews on real hardware? (Score:5, Interesting)

    by Kris_J ( 10111 ) * on Thursday March 11, 2004 @12:47AM (#8529348) Homepage Journal
    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.

    • www.tototek.com They sell a flash cart in 32Mbit and 64Mbit varieties. The 64Mbit one also supports 32x games.

    • However, I don't know of any way to get ROMs onto a Genesis/Mega Drive -- is there one?

      Cart copiers exist, but they tend to be either incredibly expensive, incredibly hard to get, or both because the companies that made them stopped selling them once new systems came out. The biggest market for copiers were asian countries with lax copyright laws and rampant piracy. Reportedly, a year or two after the PSX came out, it wasn't uncommon to see someone throwing their perfectly-working copier and stack of flo

  • What about the Z80?? (Score:3, Interesting)

    by Anonymous Coward on Thursday March 11, 2004 @12:58AM (#8529402)
    The Sega Genesis is a dual processor system containing both a 68K and Z80. Some games are sensative to the timing between the two processors. If you overclock one and not the other some assumptions about the timing is going to break. In the cases of his tests it appears to produce problems with the music since that is what the Z80 gets used for in Sonic. But in other games the Z80 is also used for video effects such as flashing icons. Even if you can get the 68K another 50% faster, you still haven't gotten the entire system correctly clocked at the new rate unless the Z80 can also handle being clocked another 50% faster.

  • Alternate suggestion. (Score:3, Informative)

    by gklinger ( 571901 ) on Thursday March 11, 2004 @01:36AM (#8529568)
    Rather than overclocking the 68000, he should consider upgrading the CPU. The Motorola 68010 is both pin and insstruction compatible and it has a slightly higher range of operational clock speeds. Way back in the day (I've always wanted to say that!) I upgrade dozens of Amiga 1000s without a problem. And yes, the upgrade was, for all intents and purposes, useless. I would tell people that and they would still want the upgrade so I let commerce take its natural course.

  • Kind'a hard to see the difference (Score:3, Interesting)

    by Aqua OS X ( 458522 ) on Thursday March 11, 2004 @02:42AM (#8529814)
    it's kind'a hard to tell the difference when we're looking at an AVI file with a set frame rate.

  • Fixed speed difficult without external timebase (Score:3, Interesting)

    by noidentity ( 188756 ) on Thursday March 11, 2004 @03:22AM (#8529939)
    A game with a varying number of on-screen objects which achieves consistent speed without relying on an external timebase is somewhat difficult to code because the execution time of every routine must be taken into account to determine the proper delay until the next frame. It's unlikely that the overall frame rate of a game would be normally determined by CPU cycles used (it will be when there is too much to process in the usual frame interval). In addition, video hardware on some consoles only allows access between frames (during vertical blanking). Even where it doesn't, if the game's frame rate isn't synchronized with the video frame rate, when updates are made in the middle of the video frame, the next completed video frame will have a split across the middle with the old frame on top and the new frame on the bottom.

    Depending on the CPU speed for short self-contained routines which access hardware in a time-critical way is probably more common, and not bad practice, since the older consoles were kept compatible at the hardware level. Keeping hardware the same across board revisions allowed elimination of a cycle-consuming software abstraction layer.
    • Most consoles at that time operated in a fairly similar fashion. The video hardware would draw the frame, and then a v-blank would be triggered. During the v-blank, you could execute code and manipulate the video data. When not in v-blank, you could calculate game related things. For example, a common game would manipulate a local set of data with the information for the sprites. The v-blank is triggered and the local data is copied into vram. V-blank ends and the process begins again.

  • Overheating (Score:3, Funny)

    by Jacek Poplawski ( 223457 ) on Thursday March 11, 2004 @03:29AM (#8529958)
    Overclocking 8-bit computers like Atari 800XL is very good thing, because these computers where often used to keep your legs warm in winter (if you don't believe me, ask older collegue, who had 8-bit computer), so additional overheating can only help :-)
    Stability is of course different problem. Overclocked Atari may work almost as badly as Windows XP.

  • that 'slow-down' was a feature (Score:3, Interesting)

    by CAIMLAS ( 41445 ) on Thursday March 11, 2004 @09:45AM (#8531379)
    I don't know about anyone else, but I actually appreciated it when my NES or genesis would slow down. It usually happened in a particularly difficult spot, and it allowed for quicker response on my part. Such slowdown is the only reason I ever managed to beat Super Mario Brothers.

    Since I couldn't afford a game genie, it was a nice substitute at times. :)

  • 68k - 68010? (Score:3, Insightful)

    by Nimey ( 114278 ) on Thursday March 11, 2004 @12:19PM (#8533087) Homepage Journal
    Is it possible to desolder the 68000 and replace it with a 68010? The '10 had better integer performance and had an identical pinout.

  • Or... (Score:3, Interesting)

    by Bert64 ( 520050 ) <bert@NOSpaM.slashdot.firenzee.com> on Thursday March 11, 2004 @01:16PM (#8533797) Homepage
    Why not pull the 68000 out and replace it with a 68010 chip, which is pin compatible, faster at the same clockrate and able to run at higher clock rates anyway...
    I always thought the megadrive 68000 cpu was clocked at 12mhz anyway, it was the Amiga 500/600 series machines which used 7mhz 68000, and one cheap upgrade path was to pull the 12mhz cpu out of a megadrive

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