Here’s a nice survey of computer front panels, with many DEC and IBM examples, but also others:
The Computer Front Panel
It’s a multi-page series:
The Ultimate Computer Front Panel
Still More Front Panels
But What Were They For?
The IBM System/360 Saga Part I: In the Beginning
The IBM System/360 Saga Part II: Extending the Range
The System/360 Saga Part III: The Case of the Bashful Computer
The Early Architectures of DEC
The Best-Loved DEC Minicomputers