SPECTRANEXT

Internet Cartridge for ZX Spectrum

A modern network cartridge for the ZX Spectrum, with WiFi, Spectranet compatibility, and support for new internet-connected software.

  • Wi-Fi
  • HTTPS
  • USB-C
  • 4MB storage
  • SDK

Available now from selected distributors:

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Features

  • WiFi networking instead of wired Ethernet
  • Fully backward compatible with Spectranet software
  • 10+ resources to navigate
  • Persistent storage for favorite games
  • Integrated pass-through expansion connector
  • Automatic HTTPS handling for compatible applications
  • Ideal for modern networking applications on retro hardware

Unbound

Unbound is a free multiplayer companion game included with the Spectranext cartridge bundle.

Players cooperate on a hostile planet: building an outpost, automating production, managing resources, and keeping the company alive over long-running sessions.

Unbound game logo
Unbound, the companion multiplayer game.
Unbound contracts and profits screen
Contracts, cash flow, and survival on the frontier.
Land on a hostile planet and start building.
Automate outpost systems to keep the operation alive.
Program in-game computers to control real colony equipment.
Defend the outpost when the planet pushes back.

Hardware & Compatibility

Spectranext plugs directly into the ZX Spectrum expansion port and includes pass-through support for other cartridges. It is fully backwards compatible with the original Spectranet, making it a drop-in replacement that preserves existing software while adding new capabilities.

Supported computers include the ZX Spectrum 48K, ZX Spectrum 128K, ZX Spectrum +2, ZX Spectrum +3, Spectrum Next, OMNI 128HQ LAPTOP, and SiZif 512. Some machines require the compatibility switch or machine-specific settings; see the compatibility documentation for details.

No complex setup required—just insert the cartridge and start using modern networking on your vintage hardware.

See more about compatibility on the Documentation Portal.

Wi-Fi & Modern Internet

Spectranext uses Wi-Fi instead of Ethernet, bringing your Spectrum into the modern era. It does networking much like Spectranet, but automatically decrypts encrypted (HTTPS) traffic so client programs for websites become possible.

Unlike the original Spectranet which only supported TNFS, Spectranext can mount and load files directly from HTTP(S) websites, opening up a world of modern internet services and content.

Development Tools

Spectranext includes a small temporary filesystem (RAMFS), allowing developers to upload programs directly into the device—almost like programming Arduino. No external server required for development and testing.

The device features an onboard debugger (GDB stub), enabling physical debugging of real hardware with stop, continue, step, breakpoints, and memory inspection. Spectranext itself can be disabled, so the debugger can be used to debug 100% native programs running on real hardware.

A USB port provides quick program testing and logging capabilities. Programs can emit logs to a terminal instead of the screen, making development and debugging much easier.

Tight integration with modern toolkits like z88dk means you can use familiar development tools, and the z88dk debugger can directly debug programs running on Spectranext.