he Yamaha YIS-503IIR is the adaptation of the YIS-503II computer for Soviet Union. It was not sold in shops and could only be used in schools. The "КУВТ" logo is the abbreviation of "Комплект учебной вычислительной техники" and means "Class of Teaching Computing Equipment".
This computer has a Russian keyboard and the specific music connectors have been replaced by 2 serial port connectors and a switch allowing the machine to work in teacher mode or in student mode. The communication between MSX computers is actually controlled by a serial network interface called Serial I/O Unit.
Note: This communication system is completely incompatible with the system used on the MSX2 YIS-503IIIR and YIS-805/128R2 computers.
| Brand | Yamaha |
| Model | YIS-503IIR |
| Year | 1985 |
| Region | USSR |
| Launch price | |
| RAM | 64kB in slot 3-2 |
| VRAM | 16kB |
| Media | MSX cartridges, (only teacher machine) DD floppy disks |
| Video | Yamaha V9938 (MSX2 VDP!) |
| Audio | PSG (YM2149 integrated in MSX-Engine S3527) |
| Chipset | Yamaha S3527 |
| Keyboard layout | JCUKEN/Cyrillic |
| Extras | 60 pin module port, mini cartridge port, serial network interface + switch + RS-232C BASIC , internal RAM / VRAM expandable, (only teacher machine) 1 external 720kB 3,5" floppy disk drive |
| Emulation | ROMs dumped and emulated with exception of the network module, side module slot and mini slot |