EUMEL (pronounced ''oimel'' for Extendable Multi User Microprocessor ELAN System and also known as L2 for Liedtke 2) is an

operating system An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ...

(OS) which began as a

runtime system In computer programming, a runtime system or runtime environment is a sub-system that exists in the computer where a program is created, as well as in the computers where the program is intended to be run. The name comes from the compile time ...

(environment) for the programming language ELAN. It was created in 1979 by

Jochen Liedtke Jochen Liedtke (26 May 1953 – 10 June 2001) was a German computer scientist, noted for his work on microkernel operating systems, especially in creating the L4 microkernel family. Career Education In the mid-1970s Liedtke studied for a d ...

at the

Bielefeld University Bielefeld University () is a public university in Bielefeld, Germany. Founded in 1969, it is one of the country's newer universities, and considers itself a "reform" university, following a different style of organization and teaching than the e ...

. EUMEL initially ran on the

8-bit In computer architecture, 8-bit integers or other data units are those that are 8 bits wide (1 octet). Also, 8-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures are those that are based on registers or data bu ...

Zilog Z80 The Zilog Z80 is an 8-bit computing, 8-bit microprocessor designed by Zilog that played an important role in the evolution of early personal computing. Launched in 1976, it was designed to be Backward compatibility, software-compatible with the ...

processor. It later was ported to many different computer architectures. More than 2000 Eumel systems shipped, mostly to schools and also to legal practices as a

text processing In computing, the term text processing refers to the theory and practice of automating the creation or manipulation of electronic text. ''Text'' usually refers to all the alphanumeric characters specified on the keyboard of the person engaging th ...

platform. EUMEL is based on a

virtual machine In computing, a virtual machine (VM) is the virtualization or emulator, emulation of a computer system. Virtual machines are based on computer architectures and provide the functionality of a physical computer. Their implementations may involve ...

using a bitcode and achieves remarkable performance and function. Z80-based EUMEL systems provide full multi-user multi-tasking operation with virtual memory management and complete isolation of one process against all others. These systems usually execute ELAN programs faster than equivalent programs written in languages such as

COBOL COBOL (; an acronym for "common business-oriented language") is a compiled English-like computer programming language designed for business use. It is an imperative, procedural, and, since 2002, object-oriented language. COBOL is primarily ...

BASIC Basic or BASIC may refer to: Science and technology * BASIC, a computer programming language * Basic (chemistry), having the properties of a base * Basic access authentication, in HTTP Entertainment * Basic (film), ''Basic'' (film), a 2003 film ...

, or Pascal, and compiled into Z80

machine code In computer programming, machine code is computer code consisting of machine language instructions, which are used to control a computer's central processing unit (CPU). For conventional binary computers, machine code is the binaryOn nonb ...

on other

s. One of the main features of EUMEL is that it is persistent, using a fixpoint/restart logic. This means that if the OS crashes, or the power fails, a user loses only a few minutes of work: on restart they continue working from the prior fixpoint with all program state intact fully. This is also termed

orthogonal persistence In computer science, persistence refers to the characteristic of state of a system that outlives (persists for longer than) the process that created it. This is achieved in practice by storing the state as data in computer data storage. Programs ...

. EUMEL was followed by the

L3 microkernel L4 is a family of second-generation microkernels, used to implement a variety of types of operating systems (OS), though mostly for Unix-like, ''Portable Operating System Interface'' (POSIX) compliant types. L4, like its predecessor microkernel ...

, and later the

L4 microkernel family L4 is a family of second-generation microkernels, used to implement a variety of types of operating systems (OS), though mostly for Unix-like, ''Portable Operating System Interface'' (POSIX) compliant types. L4, like its predecessor microkernel ...

References

{{Operating-system-stub Discontinued operating systems Microkernels