Hexadecimal Number System -- Explains the sense of using hex, and includes tips on hex-binary and hex-decimal conversions. Hex Workshop -- Home of the popular hex editor. Bart Trzynadlowski's Home Page -- Get the 68kd disassembler. Listing Gallery: Genesis Dev -- And the snasm68k assembler. M68K Assembly Tutorial -- Written by Mask of Destiny. Psy-Q Saturn Development Manual. It documents ASM68K, which is very similar to SNASM68K. (BZip2'd PDF) The MC68000 Programmers Reference Manual. The definitive reference to the 680x0 line of processors, straight from Motorola. 68000 Addressing Modes -- Know the different methods you can use to address memory space. The Guide to 68000 Assembly Language by Jimmy Mardell -- Everything you need to know about 68K from registers, flags, memory, stacks, and description of each op code. M68000 8-/16-/32-Bit Microprocessors User?s Manual -- Hardware details and programming information for the 68k family of processors, including instruction timing information. (PDF) Nemesis' Sonic hacking site (and Sonic Community Hacking Guide in SHIT) -- Complete dissections of Sonic 1, 2, 2 beta, and 3 ROM. Plus loads of info at Eidolon's Inn.