Not just a footnote of history: EUMEL ===================================== :date: 2016-08-31 :copyright: CC0_ .. _CC0: https://creativecommons.org/publicdomain/zero/1.0/ .. note:: This documentation is work-in-progress. If you want to contribute floppies, manuals or documentation contact me via `email `__ or file an issue on GitHub_. .. _GitHub: https://github.com/PromyLOPh/eumel/issues The *E*\ xtendable multi *u*\ ser *m*\ icroprocessor *EL*\ AN system (EUMEL) is a microkernel-based operating system created in the 1980s. It is sometimes refered to as *Liedtke 2* (L2), named after its inventor Jochen Liedtke. L3, EUMEL’s successor, is still in use by a few legacy systems as of 2016. .. contents:: Overview -------- EUMEL is different from conventional operating systems in a lot of ways. Some of them were neccessary due to hardware constraints at that time and others were deliberatly designed this way. EUMEL’s key features are: Hardware independence The OS has *two* hardware abstraction layers, significantly improving its portability. The first one, Software/Hardware (SHard), provides functions for a concrete machine, such as the Olivietti M20, Amiga ST or IBM PC AT/XT. EUMEL0 (Urlader), the second layer, implements a virtual machine on top of a specific processor architecture like Z80 or x86. Programs are compiled into bytecode for this machine and thus independent of the actual machine they are running on. Single-level store Every object (dataspace) lives in a single, virtual address space. The memory is organized into pages, which can reside in memory or on disk. The operating system transparently moves pages to disk if they have not been in use lately and reads them back as soon as a process requests it ([praxis2]_, p. 82). Copy on write Pages are shareable and EUMEL automatically unshares them if one copy is written to. Persistence Every file and every task is a dataspace. Since they all reside in the single-level store the machine can powered off and back on again, with all tasks starting from the point where they left off. Time-sharing and multi-user A single machine running EUMEL is capable of serving multiple “thin clients” connected via serial lines. Quick start ----------- Fortunately a set of 1.2 MB install floppy disks of EUMEL’s x86 port has been preserved. It can be installed in any virtual machine emulating an IBM PC. In this example we’re using qemu_. The `first disk`__ is optional and contains `install instructions`_ in german language. The `second disk`__ is the bootable setup programs. It creates a partition on the harddrive, formats it and installs the SHard. `Disk three`__ contains EUMEL0 and base system. 1. Create a 128 MB harddrive: ``qemu-img create root.img 128M`` 2. Start the setup program: ``qemu-system-i386 -drive file=02_setup.img,if=floppy,format=raw -drive file=root.img,format=raw`` 3. Create a new partition by pressing ``1``, confirm with ``j`` and accept the following defaults with or ``j``. 4. If the main screen is displayed again press ``0`` and confirm yet again with ``j`` to exit setup. The screen should now read “E N D E”. 5. Quit qemu and restart it with the third floppy disk. The bootloader complains that “HG ungueltig”. 6. Press any key followed by ``2`` and a confirmation with ``j``. Reset the machine again. 7. Now we have to set up the keyboard layout and time. Select “Kanal 1” with ``j``, then press ``n`` until ``pc.1.25`` is displayed and confirm. Disable “Kanal 2” and 15 with ``n`` and decline deleting those channels with ``n``. 8. Congratulations, a fully functional EUMEL is now running in your virtual machine! For the next steps head over to [praxis1]_. __ disks/grundpaket/01_readme.img __ disks/grundpaket/02_setup.img __ disks/grundpaket/03_eumel0.img .. _install instructions: 01_readme_INSTALL.txt .. _qemu: http://www.qemu.org/ .. include:: artifacts.rst Bibliography ------------ Auto-generated from `RDF graph`_. .. see formatRefs.py .. include:: bib.rst .. _RDF graph: index.ttl