If I remember correctly, this book not only goes into technical details (skim the TOC in the Internet Archive's copy), but included higher level stuff, particularly a superb and universally useful insight into what distinguished the successful '70s minicomputer vendors: they all did an adequate job of everything essential, from hardware to documentation. E.g. I don't think anyone every bought a DEC computer for the quality and/or price/performance of their disk drives (the RK-05 might be an exception), but their disk offerings were at least adequate (modulo a few goofs when they made their own, long after this book was published).

Computer Engineering: A DEC View of Hardware Systems Design by C. Gordon Bell, J. Craig Mudge, John E. McNamara, and Kenneth H. Olson

(If you're not familiar with the first and last authors, your study of DEC history should fill you in, as cafard notes elsewhere in this thread.)

http://www.amazon.com/Computer-Engineering-Hardware-Systems-...

https://archive.org/details/ComputerEngineeringADecViewOfHar...