The Interface 1 provide networking capabilities to the ZX Spectrum and is also the means through which the ZX Microdrive is used. The Interface 1 also includes a RS232 port.
The local network (ZX Net) uses screened mono leads with 3.5mm jacks, similar to the tape leads used with ZX Spectrum. A ribbon cable connects the ZX Microdrive to the left hand of the Interface.
The interface was introduced in 1983.
Mr Woodvine's Old Computer Page 