Yamaha is the producer of many chips which are used in MSX standards. They're responsible for the MSX's various video- and soundchips, but also for the MSX-Engines (highly integrated chips).
This is a picture of the Yamaha YIS503 I found on the net.
Although I'm not sure about this, it has 32kB RAM.
As you can see, this is an advertisment for the Yamaha YIS503.
I bet you're wondering what those cartridges are, huh? :)
The big cartridge on the left is the SFG-01 FM Synthesizer Unit and the other is some software for it (I can't read the title).
The advertisment lists several other possible expansions: SRG-01 RGB Unit, SKW-01 Word Processor, SMD-01 MIDI Unit.
The SFG-01 (or SFG-05) and SMD-01 were built-in in Yamaha's MSX Music computers, the CX5M (MSX1) and CX7M (MSX2) series.
This is the Russian version of the Yamaha YIS503II MSX computer. At least 7000 of these were used in schools in and around Moscow.
Besides Russian, Yamaha also made special Chinese MSX's, next to the Japanese and International versions, ofcourse.
Sorry, currently no pics of Yamaha MSX2's...