Direct Machine Environment, abbreviated DME, was a mainframe

Mainframe computer

Mainframes are powerful computers used primarily by corporate and governmental organizations for critical applications, bulk data processing such as census, industry and consumer statistics, enterprise resource planning, and financial transaction processing.The term originally referred to the...

 environment for the ICL 2900 Series

ICL 2900 Series

The ICL 2900 Series was a range of mainframe computer systems announced by the UK manufacturer ICL on 9 October 1974. The company had started development, under the name "New Range" immediately on its formation in 1968...

 of computing systems from International Computers Limited that was developed in the 1970s. DME was more-or-less an ICL 1900

ICT 1900 series

ICT 1900 was the name given to a series of mainframe computers released by International Computers and Tabulators and later International Computers Limited during the 1960s and '70s...

 order code processor in microcode

Microcode

Microcode is a layer of hardware-level instructions and/or data structures involved in the implementation of higher level machine code instructions in many computers and other processors; it resides in special high-speed memory and translates machine instructions into sequences of detailed...

, which permitted the ICL 1900 series executive, operating system

Operating system

An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

s and program libraries

Library (computer science)

In computer science, a library is a collection of resources used to develop software. These may include pre-written code and subroutines, classes, values or type specifications....

 to operate on the ICL 2900 series.

Reason for Development

At this time most companies that had computers had large teams of programmers to write their applications. DME was developed so that customers could buy the new hardware and run their 1900 or System 4 applications whilst they developed their replacement VME applications. This led to some users running DME and VME alternately on the same machine for some years. Unfortunately this led to situations where development teams were waiting around for time to run their new applications. This, and the fact that some users were not moving to the new system, led ICL to develop a system call Concurrent Machine Environment (CME) under which VME ran DME as a subsystem, enabling 1900 and System 4 applications to be run on a 2900 or Series 39

ICL Series 39

The ICL Series 39 was a range of mainframe and minicomputer computer systems released by the UK manufacturer ICL in 1985.- Origins :The Series 39 range was based upon the New Range concept and the VME operating system from the company's ICL 2900 line, and was introduced as two ranges:* Series 39...

machine alongside VME applications.