Sonic for MegaCD Proof-Of-Concept Build

The ISO packaged herein is for US Region SegaCD. There is also
a Europe Region version that is, at the time of this release,
available at http://stealth.shadowsoft-games.com/SMCDE.rar

The ISO packaged herein is for Europe Region SegaCD. There is
also a US Region version that is, at the time of this release,
available at http://stealth.shadowsoft-games.com/SMCDU.rar

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Important:

Certain claims of functionality were written into this
document during the burning of a test CD, before the hardware
was found to have unexpected, unemulated, undocumented
"problems" that did not show up in previous tests reguarding
issues that WERE known to require special care. The first
version exploited one functionality to attain more RAM storage,
however, this exploit rendered the CD reader unresponsive. This
version was created to replace it, however, the method used for
Sonic 2 during level gameplay renders the z80 sound program
useless on real hardware, thus, no sound (and some crashes)
during level play. Unless there are undocumented setup steps to
allow the use of Genesis RAM to store sound data for the z80
program on actual hardware (This is a necessary step to ensure
that the z80, which needs frequent access to DAC samples and
sound effects, still has access even when SCD Memory access
rights are swapped between processors), the only other
alternative is to replace the z80 program with a setup more
similar to that in Sonic 1 (with a DAC handler and it's samples
both stored in Z80, while a 68k program handles FM and sound
effects, only during VBlank), which would would add slowdown,
and would require conversion of all music and sound effects, as
well as new programming to accommodate for new music/sound
events that were added for Sonic 2. Without using the methods
attempted herein, there is not enough space to store the
uncompressed player art along with all other data within
most fully-developed level programs for Sonic 2

These programs remain fully functional through emulation, so
the documentation is left in-tact, with the addition of this
notice. A release of this nature is being made only because
word had already been given based on the lack of knowledge of
these unforseeable circumstances, because Sonic 1 appears
to be functional, and because of the effort already expended,
including the additional game modifications featured herein.
Testing ceases at this time, and any other use of this project
is placed on hold, pending further information and time,
allowing other projects an opportunity to be developed

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The programs featured on this ISO are proof-of-concept for
the original Sonic the Hedgehog and Sonic the Hedgehog 2
running from MegaCD. Current features include:


Intro Level:

This is a small level area that uses gameplay for selecting
the player, game, and color mode. Player and color select
are controlled by re-appearing Monitors, and game select is
controlled by each of 4 springs. Two in the upper area select
Sonic the Hedgehog or Sonic the Hedgehog 2, or two below
select the test zone in either the Sonic 1 or Sonic 2 engine,
with the tunnel on the right selecting the Sonic 2 test zone
in 2P mode

Sonic the Hedgehog:

The Title Screen and complete Green Hill Zone from the
original Sonic the Hedgehog are available, featuring relevant
enhancements from "Knuckles in Sonic the Hedgehog", including
the playable Knuckles character, as well as a spindash and
Sonic 2 style motion handling for Sonic himself, and even a
playable Tails. Knuckles and Tails games may use one of two
color modes:

  Friendly color - New character colors are forced to match
                  the game palette (with attempted minimum
                  impact) so that no original art appears
                  modified

  Aggressive color - New palettes are loaded for the new
                    characters, displaying them with their
                    correct colors, though affecting other
                    sprites (with attempted minimum impact)

Sonic the Hedgehog 2:

The Title Screen and complete Emerald Hill Zone from the
original Sonic the Hedgehog 2 are available, featuring flight
for Tails, and a playable Knuckles. Sonic and Tails 1P and
2P modes are both available, though a tie-breaker is not

Test Level:

The test levels are built from the example output data from
SonED2, which are based on Shining Island from "Sonic the
Hedgehog: Project Mettrix". This is a very brief level for
both Sonic 1 and Sonic 2 engines showing functionality of
level layout and solidity/angles with functional loop.
These playable versions feature CD playback, using music
from the previously-mentioned Shining Island. For Sonic 2,
this level also represents a functional custom 2-player
level, which also shows a working combination of both CD
tracks and normal Sonic engine music (when an invincibility
item appears). The CD track, at the time of this release,
is available at http://stealth.shadowsoft-games.com/SMCDM.rar
and should be placed in the same folder as the ISO


All programming work are modifications, enhancements, and
adaptations of other Sonic game code, by Stealth
MStealthA @ aol.com
http://stealth.emulationzone.org

Based on reverse-engineering by Hivebrain/Stealth/drx
(Sonic 1) and Nemesis (Sonic 2), and partial personal
reverse-engineering of "Sonic 2 and Knuckles", Sonic 3,
and Sonic and Knuckles

Custom Levels created with SonED2, by Stealth

Music and Sound Effects from later games now appearing in
Sonic 1 ported by Tweaker

Some mappings were converted/built with LOst Library

US SegaCD boot information provided by Mask of Destiny

European MegaCD boot information provided by LOst

Original game design, programming, art, music, etc created
by Sonic Team and used without permission, but without
intent to harm Sonic Team or Sega, and without intent to
profit. New programming, content, and implementation remain
separate properties of their respective authors