Keyboards totally do use hard drives. Modern ones are using SSDs though, but it wouldn't surprise me to learn that the older ones had actual mechanical drives. When you account for modern sample size, plus sometimes the large amount of velocity layers, flash memory isn't enough.
That said, it very well might be soldered in place. Even if you desolder it and manage not to break anything and install an SSD, there's no guarantee it would work. You'd need to clone the HDD onto the SSD. Either that or format the SSD in the way the keyboard expects and get the samples onto it some other way. Also, there might be software on the drive that it uses - it might not all be in ROM. So there are a lot of things here you'd need to find answers to before even attempting this. I'm not saying it can't be done, but you will have to be careful and dig up everything you can about the process - if it even has been done before.
Facts with Tom MacDonald, Adam Calhoun, and Dax
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