+D
From Wikipedia, the free encyclopedia
The +D (or Plus 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 the less important features of the earlier product — the network and joystick ports, the inhibit button and the pass-through connector — and replaced its ancestor's plastic 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 a Non-Maskable interrupt button. The +D's casing was simple folded steel, which was not only stronger than before but acted as a heatsink, improving reliability. Apart from the missing ports, though, it was software-compatible with the larger device.
The +D's DOS was named G+DOS, and was compatible with the DISCiPLE's DOS, GDOS. SAM DOS for MGT's SAM Coupé was backwards-compatible with GDOS and G+DOS.
The +D and DISCiPLE so extended the capabilities of the Spectrum that a user group was formed to discuss the system's newly-expanded potential. The group, INDUG, published a newsletter called Format, and later went on to become Format Publications.
For more information on the design, specification and use of the +D, see the entry on MGT.
The +D design was later licensed by Datel and it continued on sale for some years after MGT's demise. Its design and chips have been released into the public domain and it still remains available commercially or even as a DIY project if you fancy building one yourself.
[edit] External links
- How to build a +D for yourself
- rwapsoftware.co.uk still offer the +D Disk Interface for sale
