Yamaha YIS-503IIIR КУВТ2 - Japan/ Soviet MSX computer - color tv modulator - works, tested , good condition The Yamaha YIS-503IIIR is the adaptation of the YIS-604/128 or the CX7M/128 computer for Soviet Union. It was not sold in shops and could only be used in schools. The "КУВТ2" logo is the abbreviation of "Комплект учебной вычислительной техники 2" and means "Class of Teaching Computing Equipment 2". This computer has a Russian keyboard, it was generally used by the students while the teacher had a YIS-805/128R2 including two disk drives. The communication between MSX computers is actually controlled by a sophisticasted interface called Serial I/O Unit Mk II. This interface has 2 specific serial ports and an internal DIP (Dual Inline Package) switch with 4 configurable bits that define the number of student machine (1 - 15). Setting DIP to 0 makes the machine a teacher's machine. In this MSX-Network, up to 8 student machines are connected to a teacher machine using one of the floppy disk drives for centralised file storage. Note: This communication system is completely incompatible with the system used on the MSX1 YIS-503IIR computer.