UNCOL was a proposed universal intermediate language

Intermediate language

In computer science, an intermediate language is the language of an abstract machine designed to aid in the analysis of computer programs. The term comes from their use in compilers, where a compiler first translates the source code of a program into a form more suitable for code-improving...

 for compiler

Compiler

A compiler is a computer program that transforms source code written in a programming language into another computer language...

s introduced by Melvin E. Conway

Melvin Conway

Melvin Edward Conway was an early computer scientist, computer programmer, and hacker who coined what's now known as Conway's Law: "Organizations which design systems are constrained to produce designs which are copies of the communication structures of these organizations."Apart from the above,...

 in 1958. It was never fully specified or implemented; in many ways it was more a concept than a language.

UNCOL was intended to make compilers economically available for each new instruction set

Instruction set

An instruction set, or instruction set architecture , is the part of the computer architecture related to programming, including the native data types, instructions, registers, addressing modes, memory architecture, interrupt and exception handling, and external I/O...

 architecture

Computer architecture

In computer science and engineering, computer architecture is the practical art of selecting and interconnecting hardware components to create computers that meet functional, performance and cost goals and the formal modelling of those systems....

 and programming language

Programming language

A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....

. Each machine architecture would require just one compiler back end, and each programming language would require one compiler front end. This was a very ambitious goal in 1961 because compiler technology was in its infancy, and little was standardized in computer hardware and software.

The concept of such a universal intermediate language is old: the
SHARE

SHARE (computing)

SHARE Inc. is a volunteer-run user group for IBM mainframe computers that was founded in 1955 by Los Angeles-area IBM 701 users. It evolved into a forum for exchanging technical information about programming languages, operating systems, database systems, and user experiences for enterprise users...

 report (1958) already says "[it has] been discussed by many independent persons as long ago as 1954." Macrakis (1993) summarizes its fate:
UNCOL is sometimes used as a generic term for the idea of a universal intermediate language. The Architecture Neutral Distribution Format

Architecture Neutral Distribution Format

The Architecture Neutral Distribution Format is a technology allowing common "shrink wrapped" binary application programs to be distributed for use on conformant Unix systems, each of which might run on different underlying hardware platforms...

is an example of an UNCOL in this sense.