# Eumel

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Operating system

EUMEL Developer Jochen Liedtke OS family L4 Working state Discontinued Initial release 1979; 47 years ago (1979) Marketing target 8-bit computing Available in English, German Supported platforms Zilog Z80, Z8000; Motorola 68000, Intel 8086 Kernel type Microkernel Succeeded by L3, L4

**EUMEL** (pronounced *oimel* for **Extendable Multi User Microprocessor ELAN System** and also known as **L2** for **Liedtke 2**) is an [operating system](/source/Operating_system) (OS) which began as a [runtime system](/source/Runtime_system) (environment) for the programming language [ELAN](/source/ELAN_(programming_language)). It was created in 1979 by [Jochen Liedtke](/source/Jochen_Liedtke) at [Bielefeld University](/source/Bielefeld_University).

EUMEL initially ran on mainframes such as the [Siemens](/source/Siemens) [BS2000](/source/BS2000).[1] Later, it was ported to the [8-bit](/source/8-bit_computing) [Zilog Z80](/source/Zilog_Z80) processor and many other [computer architectures](/source/Computer_architecture) including the [IBM System/370](/source/IBM_System%2F370) and the [Telefunken](/source/AEG-Telefunken) [TR 440](/source/TR_440), and eventually, more recent consumer-oriented systems based on [Zilog Z8000](/source/Zilog_Z8000), [Motorola 68000](/source/Motorola_68000) and [Intel 8086](/source/Intel_8086).[1][2]

Compilers for other programming languages were added as well (e.g. [BASIC](/source/BASIC), [DYNAMO](/source/DYNAMO_(programming_language)), [LISP](/source/LISP)[3], [Prolog](/source/Prolog)[1]). Application software included the [relational database](/source/Relational_database) REMIS, the statistics package DASYS, and the eponymous [word processor](/source/Word_processor).[3] More than 2000 Eumel systems shipped, mostly to schools, universities, and also to legal practices as a word processing platform.[1] EUMEL is based on a [virtual machine](/source/Virtual_machine) using a bitcode and achieves remarkable performance and function. Even the Z80-based EUMEL systems provide full multi-user multi-tasking operation with virtual memory management and complete isolation of one process against all others.

One of the main features of EUMEL is that it is [persistent](/source/Persistence_(computer_science)), using a fixpoint/restart logic. This means that if the OS [crashes](/source/Crash_(computing)), 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](/source/Orthogonal_persistence). It was achieved using [copy-on-write](/source/Copy-on-write) and [garbage collection](/source/Garbage_collection_(computer_science)) among other cutting-edge programming techniques.[1]

EUMEL evolved into the [L3 microkernel](/source/L3_microkernel) and later the [L4 microkernel family](/source/L4_microkernel_family) which is found in the [baseband processor](/source/Baseband_processor) of mobile phones and also powers the [secure enclave](/source/Trusted_execution_environment) of [Apple silicon](/source/Apple_silicon) processors.

## References

1. ^ [***a***](#cite_ref-history_1-0) [***b***](#cite_ref-history_1-1) [***c***](#cite_ref-history_1-2) [***d***](#cite_ref-history_1-3) [***e***](#cite_ref-history_1-4) Braun, Lars-Dominik (6 April 2025). ["Not just a footnote of history: EUMEL"](https://6xq.net/eumel). Retrieved 8 December 2025.

1. **[^](#cite_ref-IWOOOS_2-0)** [Liedtke, Jochen](/source/Jochen_Liedtke) (December 1993). "A persistent system in real use: experiences of the first 13 years". *Proceedings of the 3rd International Workshop on Object Orientation in Operating Systems (IWOOOS)*. Asheville, North Carolina, United States. pp. 2–11. [doi](/source/Doi_(identifier)):[10.1109/IWOOOS.1993.324932](https://doi.org/10.1109%2FIWOOOS.1993.324932).

1. ^ [***a***](#cite_ref-manuals_3-0) [***b***](#cite_ref-manuals_3-1) ["EUMEL manuals"](http://bitsavers.informatik.uni-stuttgart.de/pdf/gmd/eumel/). *Bitsavers.org*. Retrieved 8 December 2025.

v t e Microkernels-nanokernels Kernels L4 family Eumel → L3 → L4° Macintosh hosted Mac OS nanokernel NuKernel Psion EKA1 → EKA2^° Amiga-type Exec ExecSG Quark WarpOS EROS^° K42° Little Kernel Mach° GNU Mach° MicroEmpix µ-velOSity^ nucleus Off++ → Plan B Opus PowerUP RTLinux° TI-RTOS kernel^° Vanguard Operating systems POSIX support Unix-like ARX GNU Hurd° Lites MeikOS Minix° Minix-vmd° Minix 3° MkLinux° Multi-Environment Real-Time^ (MERT – Unix-RT) OS2000 QNX^ RedoxOS° Spring Tinix UNICOS VSTa Partial ChorusOS^ Integrity^ Nucleus RTOS^ NuttX^° OSE^ RIOT^° Capability-based GNOSIS → KeyKOS → EROS → CapROS Hydra seL4^° Midori NLTSS HarmonyOS NEXT (OpenHarmony, Oniro OS) → HarmonyOS L4 kernel L4Linux^° PikeOS^ REX OS^ Wombat^° Java virtual machine JavaOS (Chorus/Jazz^ integrates ChorusOS^) JX° Macintosh hosted Unix-like MachTen MacMach Copland Classic Mac OS (PowerPC kernel) Psion EPOC → Symbian OS^° Amiga-type AmigaOS AROS° AspireOS° Broadway° Icaros Desktop° MorphOS Microsoft Singularity ThreadX^° Verve AIM alliance Pink → Taligent OS → Workplace OS Amoeba° BeRTOS^° ChibiOS/RT^° FreeRTOS^° HelenOS° µC/OS^° MQX^ OpenComRTOS^ Phantom OS^° RC 4000 SharpOS° SPIN° Thoth^ → Harmony^ → V VRTX^ Frameworks, kits Cosmos° Genode° TI-RTOS^° Developers Gordon Bell Thomas Bushnell David Cheriton Dan Dodge Per Brinch Hansen Gernot Heiser Jochen Liedtke James G. Mitchell Ike Nassi Richard Rashid Andrew S. Tanenbaum Avie Tevanian William Wulf Italics = discontinued ^ = Real-time ° = Open-source software Category: Microkernel-based operating systems Category: Microkernels

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Adapted from the Wikipedia article [Eumel](https://en.wikipedia.org/wiki/Eumel) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Eumel?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.