Sonic Classic Collection is a Nintendo DS compilation featuring several Mega Drive/Genesis Sonic games. The ability to save mid-game and resume from that point has been added.
The compilation was confirmed to be in development November 11th of 2009 when the compilation was listed, along with the included game list, on the bbfc website.[2] On November 18th Nintendo of Australia posted a news article which revealed the compilation was to be released on the Nintendo DS.[3] It was released on March 2, 2010 in North America. [4]
Game List
Emulation
Sonic Classic Collection uses a modified version of jEnesisDS by Stephan Dittrich, who was hired by SEGA and was the lead DS programmer of this game. The ROMs used in this game were modified to not show features that a single DS couldn't use, such as 2 Player modes in Sonic 2 and Sonic 3, as well as other things such as Sonic 2's options screen and Level Select. Additionally, the 
button on the DS is generally disabled, with the player pausing the game by using the touch screen, which actually pauses the emulator. As a result, several, but not all of the original cheats are rendered defunct. See the Cheat Codes section for more info. The ROM images were modified to take advantage of a bug in jEnesisDS that effectively makes them unusable in other emulators.
Strangely, the mid-boss music in Sonic and Knuckles is replaced with the Sonic 3 mid-boss music, however the same does not apply to Sonic 3 and Knuckles. Also, in every game, when Speed Shoes are used, rather than the music playing faster, the music gets higher.
Emulation Bug
The jEnesisDS emulator incorrectly emulates $Axxx and $Fxxx instructions as if they were $6xxx instructions. The $Axxx opcodes were typically used to implement system calls on 68000-based computers, and the $Fxxx opcodes were used for floating-point coprocessors. Since the Genesis doesn't run an operating system or have a floating-point unit, these opcodes are typically unused. (These opcodes trigger the Line 1010 and Line 1111 emulator traps in the Motorola 68000 CPU. If you've ever seen the "LINE 1010 EMULATOR" or "LINE 1111 EMULATOR" error in Sonic the Hedgehog or other games, that means one of these opcodes was executed, and the game doesn't have any function to handle it.)
For whatever reason, when jEnesisDS encounters an $Axxx or $Fxxx opcode, it handles it as if it's $6xxx. The 6-line opcodes are used as conditional branches; that is, if a certain condition is met, the CPU will branch to another part of the program. The Sonic Classic Collection developers decided to randomly change all of the $6xxx opcodes in the games to $Axxx or $Fxxx, resulting in a ROM image that functions normally on jEnesisDS, but breaks horribly on all other emulators.
In order to fix this bug, the $Axxx and $Fxxx opcodes need to be changed back to $6xxx in the ROM images, or an emulator needs to be hacked to handle these opcodes as if they were $6xxx opcodes. (Doing the latter option may break some obscure ROMs that depend on the A-line and F-line emulator traps.)
Also included with the game are an art gallery featuring 30 Sonic pictures previously seen in Sonic Jam and Sonic Gems Collection, and a credits screen.
Manuals
Resources
Scans
| Nintendo DS, US
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| Nintendo DS, EU
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| Nintendo DS, UK
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| Nintendo DS, Australia
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| Nintendo DS, Germany
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| Nintendo DS, Austria
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| Nintendo DS, France
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| Nintendo DS, Spain
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| Nintendo DS, Italy
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