The Acorn Archimedes computer was the starting point of one cornerstones of modern computing today - The ARM chip. The "Acorn RISC Machine" chip was designed for this new British computing platform which was popular in schools, replacing earlier BBC Micro computers (The Archimedes included a BBC Basic interpreter and BBC Micro emulator).
Many British people my age have fond memories of the Archimedes computer, sporting RISC OS (and Arthur OS before that) it provided many innovations, including a task bar (long before Windows had one), a three-button mouse that allowed you to select things without changing focus and powerful 32-bit processing. My first experience of video/audio multimedia was on a RISC OS machine.
RISC OS, like just about every competing operating system at the time, blew Windows 3.1 out of the water. The Acorn Archimedes and RISC OS platform hung on in Britain for some while, but was ultimately beat out by the PC clones becoming increasingly common in businesses, and therefore schools being moved to the same equipment.
Had the Archimedes platform hung on for just a couple years more, it could have been a key player in Internet access as it was installed into schools between 1993 and 1996. The school I was in switched to 50 Windows 95 PCs for Internet access.
The book, like most handbooks of the time, spares nobody in going into technical specifics. The ARM chip is described along with it's machine code instruction set. The file system and DOS is explained and then a guide on how to write software "modules" that add to the ROM-based OS and then full blown WIMP applications.
As a primer to commanding the machine, this book stands up there along with "The Commodore 64 Programmer's Reference Guide" for completeness and practicalness.