One ugly solution is to use one of this (native install, sd will be seen by motherboard as an IDE or as a SATA drive):
- IDE to CF + CF to SD + SD to microSD
- IDE to CF + CF to microSD (some CF to microSD also have Raid0 with up to 4 microSD, with a great improve on R/W, not so much on IO/s)
- Sata to SD + SD to microSD
- Sata to microSD
SD to microSD internally is only a cable positioning replace, i have open one of thoose adaptors.
Allways try to use microSD of highest speed you can, they give better compatibility than a pure SD, at least the pure SD ones i had tried did not worked, while a microSD and a microSDHC had worked well.
First try with a normal 8GiB microSD, then try with a microSDHC (up to 32GiB), and if you are a bit lucky also try with a microSDXC; not all cards are supported by laptop readers, first try yours from a LiveLinux to check if you can access it well Read and Write.
This is a much more elegant solution (with three really big problems) and no need to by hardware adaptors, neither open laptop to change the card, it uses the sd card slot on the side of the laptop:
- Internal HDD with NTFS for Windows Reserved partition (where BCD goes), this will be the main boot, with menu on screen to select the OS
- SD card for System partition (please put fixed size pagefile.sys on the main HDD on another dedicated FAT32 partition if pagefile.sys size is <4GiB)
- No native install, must first intall into internal HDD, inject USB drivers for the card on early stage of boot (a lot of tweaks and not allways possible), offline clone (form a LiveLinux for example) that to the SD, adapt (from Install media) the BCD entry for it to point to SD card, and pry all had gone well.
- Boot disk and system disk will be different (VeraCrypt do not support to encrypt that, both partitions must reside on same disk)
- Choosing wrong entry on boot can damage the system files at booting (remember you will have on internal HDD the BCD with entries for more than one SD, but only one connected at a tiem, so choose wrong and you may corrupt the system on the SD)
I had tried it and works great with one SD for each one of this Vista (SP1), 7 (SP1), 8, 8.1 and 10 (all are home versions, just to ensure no pro/enterprise/server addons are there to allow such boots).
Please note the (SP1), i had tried without the SP1 and they do not work, maybe because of my laptop been quite old and not having the correct drivers, or maybe because SP1 has something 'extra' that helps.
Hope someone else can replicate this, remember to search for injecting your own usb drivers into early boot stage, it cost me a lot to find for a way for my laptop (it has a touch screen that is USB and was making it harder, USB order number related).
And for thoose (like me) that the SD to microSD card adaptor does nto full fit inside, there are some of them shorter, search google images for "Shorter sd adaptor" or "low profile sd adaptor", without quotes.