Abstract: A structure for playing MIDI messages including a main-control element, a buffer memory, a MIDI synthesizer, and a pre-processor is provided. The main-control element receives tone colors and the MIDI messages, and loads at least part of the tone colors to the buffer memory. The main-control element transmits the MIDI messages to the pre-processor. The pre-processor coupled to the main-control element and the buffer memory, is used for analyzing the MIDI messages. In addition, the pre-processor dynamically determines at least part of the tone colors to be saved in the buffer memory based on the capacity of the buffer memory.

Abstract: A substrate is made of a crystallized glass having translucency and an average linear thermal expansion coefficient of ?5×10?7/° C. at 30 to 500° C. The substrate has a first surface (working surface) of a smooth surface having a surface roughness Rmax of less than 0.5 ?m, and a second surface (non-working surface) of a rough surface having a surface roughness Rmax of 4 ?m. A light shielding layer consisting of a light shielding film and an antioxidant film is formed on the second surface of the substrate through sputtering.