I never knew this was a thing. I compared the kernel (like, actually reading and comparing the disassembly) between SINIX 1.0 and SINIX 1.2, and I noticed that

I never knew this was a thing. I compared the kernel (like, actually reading and comparing the disassembly) between SINIX 1.0 and SINIX 1.2, and I noticed that in 1.2 a significant amount of kernel code for graphics support was added. I did wonder what that was for. Now I'm super intrigued that there may actually be a GUI for the PC-D/X[1] out there! I'm pretty sure the installation of SINIX 1.2 does not have that, it probably came on extra diskettes, but now I really want to double check. [1] The machine was basically called PC-D when running DOS, and PC-X when running SINIX. That's not technically true for the first revisions of the boards (where e.g. the MMU was an optional card), but all PC-Ds I remember seeing even had "PC-D/X" written on their backside already. EDIT: That book you linked seems to be for the SVR4 SINIX that came after the XENIX-based PC-D SINIX. By that time, from what I could tell from other research so far, SINIX was running on NS32032, not on 186.