> Acorn did ship a computer with the 65816—the Acorn Communicator—but when Sophie Wilson visited WDC in 1983 and saw Mensch and crew laying out the 65816 by hand, it struck her: if this motley crew on a card table could design a CPU, so could Acorn. Thus Wilson and Steve Furber forged their own CPU: the Acorn RISC Machine.
The first commercially available Acorn RISC processor was released as a co-processor for the BBC Micro. Acorn always had processors on the mind it seems as the Tube interface and protocol [1] is solely for co-processors.
There's an excellent Rasperry Pi based project, PiTubeDirect, which emulates the ARM and many other co-processors on original Acorn 6502 based hardware; Atom, Electron, Micro and Master [2]. The original expansion hardware is, as expected, incredibly rare and valuable.