Genesis:ASIC Information

This page serves to outline the various ASIC revisions used in Genesis/Mega Drive consoles.

Yamaha FC1004

This ASIC was first introduced in the original Wondermega and would see use in the VA7 model 1, VA0 through VA3 model 2, and all handheld and CD combination consoles. It combines the 315-5313 VDP, 315-5433 I/O controller, and a slightly modified Yamaha YM3438 FM synthesizer chip. Sega produced several variants of this ASIC, which are largely pin-compatible with one another.

315-5487 and 315-5487-01

The first version of the FC1004, used in the Wondermega, VA7 model 1, and early VA0 model 2 consoles. Notable for having a completely broken 50 Hz mode, and because of this, the 315-5487 and 315-5487-01 were never used in PAL consoles. If switched to 50 Hz, there will be no sound and a few games will even crash. The -01 version was manufactured by Fujitsu.

315-5487-10 (FC1004-X)

A slightly revised version of the original 315-5487. It is functionally identical except that the 50 Hz mode was removed completely, making it strictly 60 Hz. This chip is largely only found in VA0 Japanese Mega Drive 2 consoles.

315-5487•

An extremely rare variant of the 5487 with fixed 50 Hz support. Only used in very early PAL Mega Drive IIs and the Amstrad Mega PC.

315-5660 and 315-5660-02

These two ASICs are found in the vast majority of model 2 consoles, and are also used in the Wondermega M2, JVC X'Eye, Aiwa Mega CD and CDX/Multi-Mega. Both have a fully working 50 Hz mode.

315-5660-10 (FC1004-X)

A revised version of the 315-5487-10, mainly used in the VA1 Japanese Mega Drive 2 and the Mega Jet. Still has missing 50 Hz support, making it 60 Hz-only as with the 5487-10.

315-5700 (FF1004)

This ASIC was only used in the Genesis Nomad and some VA3 model 2s. It is unknown what the differences are between this and other FC1004 variants.

315-5708-01

Same as the 315-5660 but manufactured by Fujitsu.

Toshiba ASICs

During 1994, Sega also branched out to Toshiba to supply ASICs for model 2 Genesis production. These are notable in that they do not have an integrated YM3438 like the Yamaha ASICs, and consoles which used these chips instead featured a discrete YM2612 like most model 1s. As a result, the Toshiba ASICs have completely different pinouts and cannot be used in place of the FC1004 (and vice versa).

315-5685 (TC6158AF)

The first of the Toshiba ASICs. This is only found in VA2.3 model 2s with the model number MK-1631A and has a number of bugs. More information on these bugs can be found on this page.

315-5786 (T9N13BF)

A "fixed" version of the 315-5685. It is the only ASIC used in the VA2 model 2, and is also found in VA2.3 model 2s with the normal MK-1631 model number.

Yamaha FJ3002 (315-5960)

Introduced in the VA4 model 2, this is one of the first "Genesis On a Chip" (GOAC) ASICs. It combines the 68000, Z80, Z80 RAM, VDP, YM3438, I/O controller and bus arbiter into a single chip, greatly reducing production costs. It was also used in the VA1 Genesis 3.

Yamaha FQ8007 (315-6123)

The second GOAC and final ASIC used in official Sega consoles. It strips out several features that were present on the 315-5960, such as the M3 pin for Master System compatibility, horizontal and vertical sync outputs, and other signals which were mainly used by the 32X. It was mainly used in the VA2 Genesis 3, some later Brazilian Mega Drive III consoles, and later Pico systems.