I have a Yamaha PSR-550 keyboard. It was released in 2001 (it's as old as me!), and is equipped with MIDI ports:

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How can I use the serial MIDI port (marked to host) with my modern PCs? (They don't have serial ports, and the keyboard appears to be using a non-standard pinout)

A copy of the manual with specifications (hosted on my webserver) can be found here: https://rahul.party/files/psr550-6044.pdf

Also see this short article to learn more about the port.


Electrically, the "To Host" port uses RS-232 signals (when in PC mode), so you could connect it to any COM port with a simple cable.

However, the drivers that make this port available as a MIDI port are quite old, and work only with ISA(-compatible) COM ports integrated on the PC motherboard. So unless you have such an old PC, the only reasonable way is to use a USB/MIDI adapter instead.


You need a USB to MiDI adapter. I have used this one and can personally say it works with my Casio and Yamaha keyboards.

You will also need MIDI software, such as Anvil Studio. I have used the free version of Anvil Studio and can also say it works with the MIDI adapter and my keyboards.

  • The linked adapter has no optocoupler, and does not support receiving running status or SysEx messages. – CL. Dec 30 '18 at 13:09

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