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NC4016 - Novix
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General Info
Model NumberNC4016
Introduction1984 (announced)
June, 1985 (launched)
General Specs
Frequency7.5 MHz
Process3 μm
Word Size16 bit

NC4016 (formerly NC4000) was a 16-bit stack machine microprocessor designed by Novix in 1985 primarily for the Forth programming language. The NC4016 directly executes the primitives of the high-level Forth programming language. The NC4016 was capable of executing typical Forth programs as much as 20 times faster than the Motorola 68000. Novix also offered the NC4000 Small C Compiler which was compatible with the NC4016 microprocessor.

In 1988, the NC4016 design was licensed and improved by Harris Semiconductor which later rebranded the chip as the RTX2000, a radiation hardened version suitable for spacecrafts use.

The NC4016 was later replaced by the NC5016 and later by the NC6016.


In 1983 Charles H. Moore founded Novix, Inc, a company with the goal of designing a microprocessor that would execute FORTH programs optimally. The chip, which was originally named NC4000, was released as the NC4016 in June of 1985. The NC4016 was a complete stack machine. The opcodes manipulated the stack directly.

The microprocessor, which was fabricated using 3 μm HCMOS process technology, has a 7.5MHz clock capable of 10MIPS.


Due to the limitations in the gate array technology of the time, the chip did not have any on-chip memory. Three separate modules were required: for the return stack, data stack, and program and data stack.