Brand: Sinclair Research Ltd.
Model: ZX Interface 2
Country of origin: United Kingdom
First year of production: September 1983
Price: £19.95
Design: John Mathieson
The ZX Spectrum didn’t natively have any joystick ports and instead relied on keyboard input. The ZX Interface 2 featured a combination of two joystick ports and a ROM cartridge slot.
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The ROM cartridge slot allowed users to load software instantly and without any errors. The availability of cartridge software was quite limited—only ten cartridges were released by Sinclair, while another seven planned games by Parker Brothers but were never released. Because there is no memory bank switching hardware, it would only support 16 Kb ROM cartridges.
Unlike the popular single player Kempston interface, its dual player joystick ports were mapped to keys 6 to 0 for player 1 and keys 1 to 5 for player 2 using a single decoder IC (MT62001 MCE 8344). This mapping seemed at odds with Sinclair’s own keyboard layout, where the cursor keys were mapped to 5 through 8, with 0 typically being used by games as a fire button. Games written before the release of the ZX Interface 2 would typically not support this new protocol, unless it had redefinable keys. Whereas the ROM cartridges never caught on, the Sinclair joystick protocol remained popular up to the final Spectrum model, the ZX Spectrum +3.
The pass-through expansion bus would only fit a ZX Printer with its narrower ZX81-sized edge connector. The two little joystick connector plugs easily get lost.