I disagree that one should just give up on upgrading to Win10 on the Satellite C855-S5349N. I have the same model and I'm making some good headway in running Windows 10 Pro 64-bit.
With a mix of stock Toshiba Win 8.1 drivers and the thankfully ever more compatible 10 drivers, it's not half bad for a 2.40 x2 ghz sandy bridge machine (of course the intel hd graphics aren't the best, but could be worse).
In fact, the S5349N exceeds the minimum Win 10 specs. And although it runs beautiful as a Win7 machine, its a stock 8.1.
In short, just telling the dude to give it up is bs. With evolving drivers and a little tinkering, it's running the new OS great, despite being unsupported.
The rule of thumb with these brand of satellites OP is that they're Toshiba's turf first and foremost, with just enough Intel to get the fancy sticker.
Worse case scenario is that you have to get creative with mixing and matching your drivers and keep them happy first, before you can enjoy the 3rd party software.
Also
https://www.catalog.update.microsoft.com/Home.aspx is your friend. You can literally piece together brand new 2018 drivers for the aging c/216 chipset.
Good luck.
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