Most Mega Drive 2 and Genesis 3 systems actually use the core from the chip's CMOS equivalent, the YM3438 integrated into Sega- Yamaha ASIC (FC1004/FF1004/FJ3002/FQ8007).FM sound chip: Yamaha YM2612, clocked at the 68000 clock speed (7.670454 MHz in NTSC, 7.600489 MHz in PAL).Z80 performance: 0.519034 MIPS (NTSC), 0.5143 MIPS (PAL)Īudio See YM2612 and Sega Master System/Technical specifications for further information.Instruction set: 8‑bit and 16‑bit instructions.Can access 32 KB of the 68000 memory map at once (while it should be used for accessing the cartridge, setting the bank register elsewhere can work on some hardware).8 KB program RAM which the 68000 and the Z80 can freely write to (though the 68000 must request the Z80 bus).
Some games did not use the Z80, other games used it only for sample playback, but most used it for sound processing.Arithmetic logic units: 16-bit data ALU, 32-bit address ALU (2x 16-bit ALU).
Data bus width: 32-bit internal, 16‑bit external.Instruction set: 16‑bit and 32‑bit CISC instructions.Games using save memory also needed to have the memory in the cartridge map larger games, such as Phantasy Star IV, used a mapper to swap out cart space for SRAM during a save.Sega's memory map for the Mega Drive allowed games to be up to 4 MB without the use of a memory mapper games that tried to go up to 10 MB would find their memory maps crushed by the Sega CD (which took the second 4 MB block) and Sega 32X (which took 2 MB of the third 4 MB block). The 68000 has a 24‑bit address space, allowing access to up to 16 MB of memory.
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