If you are interested in Retro Computing, then you have probably come across Johnny Blanchard and his quest to port his game Jurl to as many platforms as possible . One of those platforms is the Sinclair ZX Spectrum. You can name your price to download a copy of Jurl for the ZX Spectrum .

I’ve recently become interested in how ROM cartridges work on the ZX Spectrum. They were initially introduced by Sinclair Research with the release of the ZX Interface 2. This was a joystick interface that supported two Atari style 9 pin joysticks, and included a slot for a ROM cartridge.

When a ROM cartridge was inserted and the Spectrum powered up, the internal ROM in the Spectrum would be disabled and replaced with the ROM in the cartridge. This meant games or other code on the cartridge would run instantly without needing to be loaded from cassette. However, it also meant games could not rely on any routines in Spectrum ROM, and must be standalone.

The ROM cartridge is 16 kilobytes in size. Looking at Jurl, the binary is 27,353 bytes in size. This is larger than the 16k size limit of the ROM cartridge.