Short video on how to check the firmware version on a Yaesu FT-991 Radio.
This technique will display the version information for Main, DSP, TFT and C4FM. Details on the different sofware verisons and upgrading can be found on the Yaesu site here. Checking the firmware is not difficult – start with the radio off and then hold hold down A=B and A/B and power on – you will see the software versions. Details in the short video below.