A ROM cartridge containing 12K of fig-FORTH, RS232 interface via an 8251, and 24 bits of parallel I/O via an 8255.
The BASIC ROM is switched out and replaced by the Forth ROM.
Features a Z80 assembler for machine code FORTH definitions; a built-in terminal to support a modem and allow access to bulletin-board systems; a machine code monitor which can operate in any number base; RS232 and Centronics printer routines, usable from FORTH or BASIC; RAM disc simulation and support of Microdrives.
Has a standard DB25 RS232 connector for the serial I/O and a strip cable connector for the parallel I/O.

Suitable for both 16K and 48K ZX Spectrum.