amplifiers and have little effect on the amplitude of the digital signal. To prevent signal overflow, each individual part's volume (controller #7) must be kept low instead. A third-party solution In the period of 1989 to 1993, Robin Whittle of Real World Interfaces offered aftermarket modifications to the MT-32 to address its sound quality issues, as well as improve the functionality of the reverberation unit, provide discrete analog outputs for the internal reverb send and reverb return, and provide battery backup of the MT-32's settings. According to documentation written in 1990, these modifications were only available for the first-generation MT-32, and not the later "headphone" model or any of the other MT-32 derivatives. Note that the RWI modifications were intended for those using the MT-32 professionally, and may cause some minor compatibility issues with video game soundtracks intended for a stock MT-32. In particular the changes to the reverb unit functionality will likely cause an RWI modified MT-32 to render reverberation differently from what was intended, with possibly detrimental effects. Compatibility problems First generation units, having control ROM versions below 2.00, require a 40 millisecond delay between system exclusive messages. Some computer games which were programmed to work with the compatible modules (see above) or later ROM versions that do not require this delay, fail to work with these units, producing incorrect sounds or causing the firmware to lock up due to a buffer overflow bug, requiring turning the unit off and on. However, some games were designed to exploit errors in earlier units, causing incorrect sound on later revisions. Also, some games were written to use instruments not found in the MT-32 models, and require a compatible module, such as a CM-32L, for proper sound playback. Music for PC games Despite its original purpose as a companion to other professional MIDI equipment, the MT-32 became one of several de facto standards for PC computer game publishers. Sierra On-Line, a leading PC game publisher of the time, took an interest in the sound-design of its PC games. Sierra secured a distribution deal to sell the MT-32 in the US, and invested heavily in giving its game titles (at the time) state-of-the-art sound by hiring professional composers to write in-game music. King's Quest IV, released in 1988, was the first Sierra title with a complete musical soundtrack scored on the MT-32. The MT-32 with a necessary MPU-401 interface cost $550.00 to