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Author: Admin | 2025-04-28
This page serves to outline the various ASIC revisions used in Genesis/Mega Drive consoles.Yamaha FC1004This 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 315-5487-01The first version of the FC1004, used in the Wondermega and VA7 model 1. 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 early VA0 NTSC model 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 315-5660-02These 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, CDX/Multi-Mega, Pioneer PAC-S1/10, and some Brazilian VA7s[1]. 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 primarily used in the Genesis Nomad and some VA3 model 2s. It has been found in some Model 2 VA1.8 units as well. It is unknown what the differences are between this and other FC1004 variants.315-5708-01Same as the 315-5660 but manufactured by Fujitsu.Toshiba ASICsDuring 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
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