Definition
The ZX Interface 1 is a hardware peripheral designed for the Sinclair ZX Spectrum home computer. It expands the Spectrum’s capabilities by providing a serial RS‑232 port, a proprietary networking interface, and support for Atari‑style joysticks.
Overview
Released by Sinclair Research in 1985, the ZX Interface 1 connects to the Spectrum’s expansion port and was intended to broaden the system’s utility for both productivity and gaming. The device enabled the Spectrum to communicate with external devices such as printers, modems, and other Spectrums via a simple local‑area network (LAN). Although the networking feature saw limited commercial adoption, the joystick ports were widely used for game controllers, particularly in titles that required two-player input.
Etymology / Origin
The name “ZX Interface 1” follows Sinclair’s naming convention for peripheral add‑ons to the ZX Spectrum line. “ZX” denotes the computer series, while “Interface 1” indicates it is the first officially supported interface expansion released by the company.
Characteristics
| Feature | Description |
|---|---|
| Serial Port | RS‑232C connector supporting data rates up to 19.2 kbps, allowing connection to printers, modems, and other serial devices. |
| Networking Port | Proprietary 5‑pin DIN connector used for a simple daisy‑chained LAN, permitting up to 8 Spectrums to exchange data for multiplayer gaming and file sharing. |
| Joystick Ports | Two Atari‑compatible 9‑pin connectors, enabling the use of CX5‑ or CX10‑type joysticks for two‑player games. |
| Power Requirements | Draws power from the Spectrum’s expansion bus; no external power supply is needed. |
| Compatibility | Designed for the original ZX Spectrum (48 KB and 128 KB models). Later models such as the ZX Spectrum +2 and +3 required a separate adapter or were incompatible without modification. |
| Firmware | Includes a ROM that provides basic drivers for the serial and joystick functions; no user‑upgradable firmware was provided. |
Related Topics
- Sinclair ZX Spectrum – The 8‑bit home computer for which the Interface 1 was developed.
- ZX Spectrum +2 / +3 – Later Spectrum models that offered built‑in joystick ports and other peripherals, reducing the need for Interface 1.
- Peripherals for Home Computers – A broader category encompassing devices such as disk drives, printers, and network adapters for 1980s home computers.
- Atari Joystick Standard – The joystick connector type supported by the Interface 1, widely used across multiple platforms.
- RS‑232 Serial Communication – The standard serial protocol employed by the Interface 1 for external device connectivity.