I stumbled across this Yamaha Tyros 4 teardown on Youtube. Although the video is a little bit long-winded, you get a peek under the hood of the Tyros 4 and see a few of the circuit boards.

Unfortunately, the video is short on the kinds of details that you would find in a Yamaha service manual. I wish that the producers had taken a close pan of the main logic board with enough resolution to read the part numbers. The narrator read off the part number of the main CPU, Renesas R8A77310D, but then stated that he couldn’t find information on the web. OK, here’s the info. It’s a Renesas SH7731 processor containing an SH4AL-DSP core. The maximum clock speed of the SH7331 is 333.4MHz. The SH-4 core is a rather powerful, DSP-capable core.

The narrator also mentioned an Altera Cyclone. This is a field programmable gate array (FPGA) which probably provides some glue logic like a bus bridge. Since it’s an FPGA, it could be programmed to do just about anything.

The video shows at least two other very large scale integrated circuits. Two of these are probably SWP51 tone generators. The SWP51 has two 16-bit wave memory ports (each with separate address and data ports). Therefore, the IC package is big and has a lot of pins. The SWP51 is where Yamaha keeps the secret sauce. They have never published papers about it and with good reason; Korg, Roland and Casio would probably love to know what’s inside, too!

Given that the Tyros 4 has Vocal Harmony 2, it most likely has an SSP2 chip.

Leaving the video aside, here’s a few “big picture” thoughts.

First, it’s interesting to see how Yamaha have been riding the CPU and memory technology curves. They have used successively more powerful SH architecture CPUs over the years. They clearly have deep knowledge and competence with this architecture. Memory-wise, they have progressed from mask ROM to bulk programmable ROM (P2ROM) to NOR/NAND flash. NOR/NAND flash is so widely used in the PSR-S950, for example, that the entire machine — in theory — could be reprogrammed.

Next, if I were Yamaha, I would consider using an ARM system on a chip (SOC) in the entry level and possibly the lower mid-range keyboards. They could achieve a higher level of functional integration with ARM and still obtain low power consumption. Further, they could provide superior tone generation at the entry level. The proof point is the Yamaha Mobile Music Sequencer (MMS) app on the Apple iPad. MMS on ARM supports eight tracks of playback with a polyphonic, XG-like software tone generator. MMS provides basic XG variation effects which are not current entry-level features. Of course, this means that Yamaha is willing to leave its comfort zone with the SH architecture!