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Difference between revisions of "Sonic Classics"

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(Add diferences for Sonic 2)
(Differences (Sonic 2))
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It was conjectured for some time that the version of ''Sonic 2'' included in ''Sonic Classics'' was the former game's REV02, ''i.e.'' a second update to its code that had been officially (if silently) made by Sega themselves. This was shown conclusively in June of 2012 when [[User:Esrael|Esrael]], who was now using this version as the code-base for his famed hack ''[[Sonic 2 Delta]]'', released a ROM of the game extracted to work on its own and {{LinkRetro|post=693487|title=followed}} this shortly thereafter with [[Disassemblies#Revision 02|his disassembly of said ROM]], which demonstrated that Sega had implemented various bug-fixes and other alterations to the code in time for ''Sonic Classics''.
 
It was conjectured for some time that the version of ''Sonic 2'' included in ''Sonic Classics'' was the former game's REV02, ''i.e.'' a second update to its code that had been officially (if silently) made by Sega themselves. This was shown conclusively in June of 2012 when [[User:Esrael|Esrael]], who was now using this version as the code-base for his famed hack ''[[Sonic 2 Delta]]'', released a ROM of the game extracted to work on its own and {{LinkRetro|post=693487|title=followed}} this shortly thereafter with [[Disassemblies#Revision 02|his disassembly of said ROM]], which demonstrated that Sega had implemented various bug-fixes and other alterations to the code in time for ''Sonic Classics''.
  
===Differences (Sonic 2)===
+
===Differences===
 
====Main differences====
 
====Main differences====
 
*All the changes from REV01 are here except for a single nop added in REV01.
 
*All the changes from REV01 are here except for a single nop added in REV01.
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*The Tornado's code was altered so it's no longer possible to spindash off it whether it's a bug or not it was reverted in the 2013 remake.
 
*The Tornado's code was altered so it's no longer possible to spindash off it whether it's a bug or not it was reverted in the 2013 remake.
 
*Due to a single line of code being changed it's possible to stand on air in WFZ after the opening and closing platforms close.
 
*Due to a single line of code being changed it's possible to stand on air in WFZ after the opening and closing platforms close.
 +
 
==Cheat codes==
 
==Cheat codes==
 
The original cheat codes contained on the cartridge still work here, but the game enhancer codes do not. See [[:Cheat Codes:Sonic Classics]].
 
The original cheat codes contained on the cartridge still work here, but the game enhancer codes do not. See [[:Cheat Codes:Sonic Classics]].

Revision as of 01:19, 30 September 2018

Not to be confused with the website Sonic Classic or the fangame Sonic the Hedgehog Classic.

n/a

SonicClassics title.png
Sonic Classics
System(s): Sega Mega Drive
Publisher: Sega
Developer:
Publisher(s) of original games: Sega
Developer(s) of original games:
Sonic Team, Sega Technical Institute, Compile
Game total: 3
Original system(s): Sega Mega Drive
ROM size: 3 MB
Number of players: 1-2
Release Date RRP Code Rating
Sega Mega Drive
EU
1995  ? 1190-50
Sega Mega Drive
US
1997-08  ? 1190
Sega Mega Drive
AU
?  ? FSON16SMC
Sega Mega Drive
BR
?  ? 042780
Sega Mega Drive
KR
?  ? ?
Sega Mega Drive
PT
1995  ? 670-7105-50

Sonic Classics (USA) a.k.a. Sonic Compilation (Europe) is a compilation of three games for the Sega Mega Drive stored on a single cartridge: Sonic the Hedgehog, Sonic the Hedgehog 2, and Dr. Robotnik's Mean Bean Machine. Sonic Classics was included as a pack-in title with some editions of the Mega Drive hardware in Europe. The game was not released in Japan.

The three games appear in almost exactly the same form as in their original release, with the exception of some revisions to their code (see their individual sections below). The only new content is a game selection menu, controlled by using the left and right directions on the D-pad and new sprite renderings of the box art for each of the three games. Once a game is selected, players are not able to go back to the menu unless the console is reset or turned off and on again.

This game is one of two that, when "locked on" with Sonic & Knuckles, will enable players to play the entire Blue Sphere game, instead of just one level. The other game that enables this is the standalone version of Sonic the Hedgehog. This is because when locked-on to a ROM larger than 2MB, Sonic & Knuckles maps the last 2MB of the locked-on ROM rather than the first 2MB, and Sonic Classics happens (or was designed?) to put Sonic the Hedgehog at the 2MB mark. This is a quirk in the Sonic & Knuckles cartridge's mapper, which is not reproduced in emulators.

The background music and chime heard when a game is selected in the menu are from Dr. Robotnik's Mean Bean Machine itself.

Sonic the Hedgehog

This version of the original game is the same as the standard worldwide REV00 release, except for a new bug in Scrap Brain Zone involving the cycling palette. The bug is caused by the fact that the pointers for palette data are only two bytes long. In Sonic 1 alone, this isn't a problem because palette data lies within the first 0xFFFF of the ROM. However, in Sonic Classics, the data comes after 0x10000, so part of the address is truncated in the pointer, causing incorrect data to be loaded.

Sonic the Hedgehog 2

It was conjectured for some time that the version of Sonic 2 included in Sonic Classics was the former game's REV02, i.e. a second update to its code that had been officially (if silently) made by Sega themselves. This was shown conclusively in June of 2012 when Esrael, who was now using this version as the code-base for his famed hack Sonic 2 Delta, released a ROM of the game extracted to work on its own and
Sonic Retro
followed
this shortly thereafter with his disassembly of said ROM, which demonstrated that Sega had implemented various bug-fixes and other alterations to the code in time for Sonic Classics.

Differences

Main differences

  • All the changes from REV01 are here except for a single nop added in REV01.
  • Removed a bunch of JmpTo commands improving performance.
  • Some add/sub commands where optimized to addq/subq.
  • The header was changed from GM 00001051-01 to GM 00001051-02.
  • Removed ALOT of nop commands.
  • For some reason the duplicate PLC entries were changed.

Bug fixes

  • Removed "Level ID 02's" level scrolling code.
  • Fixed a bug where the if the player got a time over during the WFZ to DEZ transition the game wouldn't clear it causing the background to mess up.
  • Fixed a infamous bug where the Sonic could transform after hitting a signpost.
  • Fixed the infamous Rexon crash bug.
  • Interestingly HPZ's and OOZ's ani art code was altered.

Issues

  • For some reason the code which inherits the X&Y flip was altered to only inherit the Y flip causing a bug where Mecha Sonic's skids and the grabbers legs don't flip.
  • The Tornado's code was altered so it's no longer possible to spindash off it whether it's a bug or not it was reverted in the 2013 remake.
  • Due to a single line of code being changed it's possible to stand on air in WFZ after the opening and closing platforms close.

Cheat codes

The original cheat codes contained on the cartridge still work here, but the game enhancer codes do not. See Cheat Codes:Sonic Classics.

Game secrets

See: Game Secrets:Sonic Classics.

Manuals

Physical scans

Mega Drive, US
Sonic Classics 3-in-1 (BS).jpg
Cover
Mega Drive, EU
Compilation-box-eu.jpg
Cover
Mega Drive, AU
SonicCompilation MD AU Box.jpg
Cover
Mega Drive, BR
Classics md br cover.jpg
Cover
Scomp-md-br-cart.jpg
Cart
Mega Drive, KR
Sonic Classics 3-in-1 (Korea).jpg
Cover


Sonic the Hedgehog games for the following systems
Sega Mega Drive

Sega Mega-CD
Sega 32X
 1991  Sonic the Hedgehog | Sonic Eraser     1992  Sonic the Hedgehog 2     1993  Sonic the Hedgehog CD | Dr. Robotnik's Mean Bean Machine | Sonic Spinball     1994  Sonic the Hedgehog 3 | Sonic & Knuckles     1995  Chaotix | Sonic Classics     1996  Sonic 3D: Flickies' Island