Binary Hacking

Here's some basic hacking information for you to muck around with! This page is of course, always under construction, and it will be expanded when I sort out my hacking notes and such.
 

Contents:

Sonic's mappings

Sonic's mappings start at 0x1CDE. The format is as follows:
        2 bytes -- X offset
        2 bytes -- Y offset
        1 byte -- Y size of sprite
        1 byte -- X size of sprite

followed by uncompressed raw data. One byte represents two colours.

Object editing

Each object is 20 bytes long. Format for object data:
        4 bytes -- Possibly identifier for objects (to keep track of teleporters, etc..) ?
        2 bytes -- X co-ord
        2 bytes -- Y co-ord
        2 bytes -- ?
        8 bytes -- Address to go to for displaying (i.e. type of object)
        2 bytes -- ?

The rest hasn't been worked out yet! :)

Flipper positions

This is the format for flipper positions:
        4 bytes -- all 0x00
        2 bytes -- X co-ord
        2 bytes -- Y co-ord
        1 byte -- direction: 0x00 for left flipper, 0x40 for right flipper
        1 byte - 0x00

Palettes

Each palette is 32 bytes long. The starting address for the palettes is 0xDFC. I think the format for palette colours is 0RGB (i.e. 2 bytes), but i'm not sure.
(e.g. the 1st palette is 32*0 bytes from 0xDFC, the 4th palette is 32*4 bytes from 0xDFC etc...)
Here's a table of the different palettes:

Text editing

Location of HUD messages is 0xBE320. Lots of in game messages, special stage messages and credits. Have fun.
Note: ( is left part of Robotnik face, ) is right part.
%d means it inserts a number, e.g. (You still need ... emeralds)

Binary map

Here is a map or table of different locations in the ROM: