# Yamaha YM2413/OPLL the YM2413, otherwise known as OPLL, is a cost-reduced FM synthesis sound chip, based on the Yamaha YM3812 (OPL2). thought OPL was downgraded enough? :p OPLL spawned also a few derivative chips, the best known of these is: - the myth. the legend. THE VRC7. 6 channels, *rather interesting* instruments sound bank, no drums mode - Yamaha YM2423, same chip as YM2413, just a different patch set - Yamaha YMF281, ditto # technical specifications the YM2413 is equipped with the following features: - 9 channels of 2 operator FM synthesis - A drum/percussion mode, replacing the last 3 voices with 3 rhythm channels - 1 user-definable patch (this patch can be changed throughout the course of the song) - 15 pre-defined patches which can all be used at the same time - Support for ADSR on both the modulator and the carrier - Sine and half-sine based FM synthesis - 9 octave note control - 4096 different frequencies for channels - 16 unique volume levels (NOTE: Volume 0 is NOT silent.) - Modulator and carrier key scaling - Built-in hardware vibrato support # effects - `11xx`: set feedback of channel. - `12xx`: set operator 1 level. - `13xx`: set operator 2 level. - `16xy`: set multiplier of operator. - `x` is the operator (1 or 2). - `y` is the mutliplier. - `18xx`: toggle drums mode. - 0 disables it and 1 enables it. - only in drums system. - `19xx`: set attack of all operators. - `1Axx`: set attack of operator 1. - `1Bxx`: set attack of operator 2.