Megadrive/Genesis

The Megadrive (or Genesis as it was known in the America) was Sega's 16 bit console for the early 90s. It was one of the best consoles of that era, being released before the SNES and providing high quality games that far outstripped the then aging Master System. The megadrive was also the platform that bore the legendary Sonic the Hedgehog that changed the face of platform gaming forever. Hundreds of superb games were released for the Megadrive, with the big names of the gaming world moving in, to develop for it. Indeed the console only really died recently with even a FIFA '97 game having been written for it.

For many games players in Europe, the megadrive was the height of gaming technology with such a variety of games, and the power to go with them. The graphics were also a great improvement, being well utilized to give parallax scrolling and a variety of other effects that Master System owners could only dream of. Indeed, since the megadrive had some of the most renowned game development companies working on games for it, it is unsurprising that in many fields the quality of the megadrive games far exceeds that of native Acorn games.

M.E.S.S.

The Megadrive driver, written by our very own Gareth Long, is the first megadrive emulator on the Acorn. The emulation is reasonably accurate, although several games do suffer problems (which have apparently been fixed for the next version). A general problem with every Megadrive emulator, is that of palette splitting as often used for underwater effects (see level 2-2 of Sonic 2), where the screen palette changes partway down the screen and is nearly impossible to emulate properly. Unfortunately the driver is very slow, reportedly running at upto 25fps on a StrongARM (at times), but only 3 seconds per frame on an ARM700. As a result the sound emulation which is pretty good actually sounds stretched and of a poor quality. In fact with a frame skip of 3, Sonic only runs at 23% of normal speed on a StrongARM.

This driver does look very promising, but will need speeding up considerably in order for it to be any real use. With a possibility of ARM code CPU cores, and improved generic source code (remember, this is only the first release) I think we can look forward to a usable MESS driver in the near future.

Speed Rating: ARM 2 ARM 250 ARM 3 ARM 6 ARM 7 StrongARM

MESS

Coming soon...

The good news for megadrive emulation on the Acorn, is that simultaneously to writing the Megadrive driver for MESS in C, he has also been writing an ARM code megadrive emulator. Since it is highly optimised towards running on the Acorn, the ARM code version is a lot faster and will immediately replace MESS upon release. It looks like the ARM code version will be released commercially through a 3rd party publisher, rather than as freeware, though the deal is yet to be finalised. Previously this was to be through Acorn themselves, but since Kevin Lingley (the main emulation enthusiast at Acorn) left, any Acorn dealing fell through. This has led to some delay, since the emulator has been nearly complete for several months now, but is unreleased due to other commitments.

Recently, Warm Silence Software have expressed an interest in publishing Gareth's megadrive emulator. Already well known for publishing 6502Em and Z80Em, they would be well suited to the task of dodging the legal grey area. Whether they will publish it or not remains to be seen....

Technical details
CPU - MC68000 running at 8 MHz and a Z80 running at 3.5 MHz.
Display - 320x224 at 60 Hz, displaying 64 colours at once, from a palette of 4096.
Sound - SN76496 chip running at 4.289772 MHz and YM2612 chip.
ROM - upto 4 Mb
reference - MESS docs

ROMs:
Megadrive ROMs
Genesis ROMs
Planet ROM's megadrive ROMs
The Underworld's megadrive ROMs
Sega Genesis Page
Reviews and Roms (and worms!)
ROM dungeon

Recommended ROMs:
Road Rash 1 & 2, Sonic 1 2 3 & Knuckles & 3D, Micro Machines 1 & 2, Phantasy Star 2-4, Mortal Kombat 1,2,3, Earthworm Jim, Speedball 2, Desert Strike, Jungle Strike, Worms, Thunderforce3, Dune2, Ecco the dolphin 1 & 2, Rock and roll racing.