> Maybe installing BIBM as a first step would be useful? Get BIBM &
> Windows working, then go to Linux?
One word of caution: BIBM cannot act as a boot manager on a system with boot disks that use Guid Partition Tables (GPT). BIBM can boot only disks that use MBR or EMBR.
GPT is a pre-requisite for UEFI boot. So if your system currently uses UEFI boot, it will have GPT disks.
Now, it is possible to convert GPT to MBR or EMBR, but it requires some care. There is a Terabyte Knowledgebase article with instructions. I tried this on a test install of Windows 10, and messed it up -- the result was unbootable and irrepairable.
I re-installed Windows 10 from the Windows Recovery USB drive and had another attempt -- this time I was successful. (There is a critical step to getting this right; I will describe it if you want to give this a try.)
For my new Lenovo laptop, there is another "gotcha". The Lenovo BIOS Update Utility works only with UEFI boot. (I tried last week with legacy boot, and it would not work.) So if in the future I want to update the BIOS again (and since it is a current model there might be more BIOS updates), I cannot convert to MBR/EMBR, because they do not allow UEFI boot. So I cannot make the Lenovo a multiboot system.
(Well, I could do, by having a replacement C: disk setup with GPT and Windows 10, and then physically swapping the EMBR C: disk with the GPT C: disk, but that is a lot of hassle.) Hopefully your Toshiba will not suffer from this "gotcha".
-- from CyberSimian in the UK