The "Sirius microcomputer" pictured as "The Book Machine" is in fact a Victor 9000, as you can see in the picture. The same unit was branded as "Sirius" in Europe and as "Victor 9000" in the U.S.
I spent quite a lot of time with the Victor 9000 in 1983-1985, as my college bought a bunch of them, and I was the student computer lab guy who supported them. It was a fascinating machine with some really cool specs: built-in 800x600 pixel monochrome graphics, redefinable keyboard and character set layouts, built-in serial and parallel ports, high-density floppy drives, and an 8086 processor. It ran CP/M-86 and MS-DOS. Its closest competitor was the original IBM PC, which at that time had low-density floppies, no graphics, no built-in ports, etc.
The downfall of the Victor 9000 was that it pre-dated the rise of the "PC-clone": third-party PCs that could run exactly the same shrink-wrapped software as the IBM PC did. In the CP/M-80 8-bit world, every manufacturer had its own disk formats, screen sizes, and so on, and you had to buy shrink-wrapped software for your own specific hardware, and the Victor-9000 folks assumed that the 16-bit world would work the same way. As a result, they produced a much better machine than the IBM PC...that wasn't fully compatible.