Upgrade the CPU in your Sega Genesis/Mega Drive
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Written By: User:Robivy64
The Sega Genesis game system uses a Motorola-manufactured 68000 CPU as its main processor. For a short time after the Genesis was released, Motorola released a newer updated chip that was originally designed to supercede the 8 year old 68000 design, the 68010. It is similar to the Motorola 68000 CPU, with the exception of the ability to save all of the processor state on an interrupt and exception, and the addition of several new instructions sets for breakpoint and register control.
Additionally, the 68010 had a loop mode that was considered to be a mini instruction cache, which accelerates loops that consist of only 2 instructions.
The 68010 was not 100% software compatible with the 68000 since the modified instruction set poses a problem for some software, but we will get to this. Unfortunately the 68010 was far more expensive than the more readily available 68000, and few companies converted to using this new chip.
The 68010 in a Genesis
Most Amiga and Mac users later upgraded their systems with the 68010 processor to get a small performance boost, but this didn't come without cost. The Mac OS and Amiga Workbench required a patch be installed to allow it to be fully operational. In the case of the Genesis, installing such a patch is not possible.
Performing this upgrade is as easy as directly replacing the Genesis CPU. The hardest part is finding the illusive 68010 CPU. These were hard to find 10 years ago, and this is especially true today. If one shows up on ebay, expect to see Amiga fans jack up the prices.
The results
After performing this upgrade users can expect to immediately notice a small speed boost off-the-bat. One unusual difference was that the PCM audio snippets in games sounded much clearer than before. Some games utilized these improved features, while others did not. There were a few games that should be mentioned that do not agree with this new CPU:
- Sonic 3 - Does not load a level
- Sonic and Knuckles - constantly reboots in a loop
- Red Zone - Does not load a level
- Street Fighter II - Does not get past the title screen
It's defnitely an interesting modification recommended for any hardcore console hardware modder, but with these incompatabilities, it's also a good idea to keep a second Genesis around for good measure.
Disclaimer
All modifications posted on Wiki-Scene are provided for information purposes only. No guarantee of desired results is written or implied. In other words: Do this at your own risk. The creators nor users of Wiki-Scene hold any responsibility for damages caused from attempting any of the hosted modifications.
This article is (c) 2006 [Underground Console Mods] and Robert Ivy. Permission has been granted by its creator to share and further expand this information on Wiki-Scene.
