PlusD
The Plus D (or "+D") was a floppy disk and printer interface for the Sinclair ZX Spectrum home computer, developed as a successor to Miles Gordon Technology's earlier product, the DISCiPLE. It was designed to be smaller, cheaper, simpler and thus more reliable.
It discarded a number of features of the earlier product, such as less important interfaces and a pass-through connector, and replaced its ancestor's wedge-shaped design which fit under the Spectrum with a simple flat metal slab which protruded from the rear of the computer.
It provided only floppy-diskette and Centronics parallel interfaces, plus an NMI button. The metal of the casing acted as a heatsink, improving reliability. Apart from the missing ports, though, it was software-compatible with the larger device.
