Sinclair Research ZX Interface 2 peripheral
Plugged into the expansion bus of a ZX Spectrum. Added 2 Sinclair-only joystick ports, a 16 KiB maximum ROM cartridge slot, and printer pass-through.
The first video game about Sinclair Research ZX Interface 2 peripheral was released in 1983.
Alternative Software has published all these games
Due to technical limitations, ZXi2 cartridges cannot include RAM. The design of the ZXi2 and ZX Spectrum units are hostile to bankswitching. Despite this, programmers have designed cartridges of 64k, 128k, 256k, and 512k in size. These cartridges are not without unusual limits. 512k cartridges, for example, can only load 8k at a time (half the speed of a standard cartridge). Plus, they have an unusually high software overhead required to load data from this half speed interface and they will be loading the different 8k segments a lot. Still, it is faster than loading from a cassette or disk, which is the main reason to use cartridges on 8-bit computers.