What is new?


  • Building a TMS9995 single board computer.
  • The odyssey of repairing a HP3330B.
  • After quite some years my friend Ingo Klöckl and I met again for a weekend full of programming. We managed to implement a skeleton of a FAT file system for a Z80 based computer - I am quite surprised by the difficulties we encountered in doing so, but the resulting monitor code runs like a charm and the Z80 system can now read FAT disks and load data from such a disk.
  • During my Christmas holidays I installed a BSD 2.11 UNIX on one of my PDP11 systems. Since there were quite a lot of pitfalls, I wrote down the necessary steps to bootstrap and configure such a system here.
  • The tinyZ80 computer has been extended with an IDE interface, the monitor now supports basic disk functions etc. Have a look. :-)
  • On October 29th, 2010, I will deliver a short talk about the current state of the 5-interpreter at this year's OpenVMS-Technical-Update-Days in Bad Homburg. The slides for this talk can be found here.
  • I bought a wonderful Fluke 8300A DVM in an online auction for a mere 18 EUR - although it still is a bargain, it took me quite some time to find and fix all faults in the instrument. The repair of this DVM is described here.
  • One of my beloved Telefunken OMS 811 oscilloscopes died some time ago - no trace, nothing. This page describes how the device was repaired.
  • I bought a Tracor 527E Frequency Difference Meter which I use to compare various oscillators to my homebrew Rubidium oscillator. The page linked to above describes this interesting device as well as the steps that were necessary to get it up and running again.
  • I enhanced the homebrew Rubidium oscillator by adding a quad D-flip flop to reduce phase jitter.
  • Last year in August I started developing a simple Perl based interpreter for a stack based array language called 5. This project may now be found at http://lang5.sourceforge.net/.
  • Another project which was on hold for quite some time is a new processor design, called QNICE, which borrows heavily from my NICE processor, has now found its way to Sourceforge, too.
  • During the Connect symposium 2009 which took place in Darmstadt, I delivered two talks: One about my new toy, a stack based array language called 5, and one about an agile method for software development which gains more and more momentum: Scrum.
  • Inserted a great idea from Noud into the page describing the simple DCF77 antenna.
  • On 08-JUL-2008, I delivered a talk entitled "How to get to the moon and back -- The Apollo onboard computer AGC" describing the way to the AGC, its development, usage etc. The slides for this talk can be found here (ca. 43 MB).
  • On the following day, July 9th, 2009, I had my final examination for my Ph.D., my disputation, the slides for which can be found here (ca. 35 MB).
  • The analog computer pages have now really been migrated to a new location, namely to http://analogmuseum.dyndns.org where you will quite a lot of new documentation for download.
  • Someday in November 2008 (I really forgot the exact date) I had a talk at the University of Hamburg titled "Von der Raketensteuerung zum Analogrechner - Helmut Hoelzers Peenemünder Arbeiten und ihr Erbe". The slides for this talk can be found here (ca. 1 MB).
  • On July 19th, my friend Dr. Matthias Koch came with a mathematical question to my birthday party. We solved the problem first analytical and on the following day I did a small analog simulation to confirm our findings. Read more here.
  • On June, the 5th, 2008, I held a talk about Thomas Samuel Kuhn's seminal book "Die Struktur Wissenschaftlicher Revolutionen" at the Johannes Gutenberg University, Mainz. You may find the accompanying slide set here.
  • On the very same day, June, the 5th, 2008, I also had a talk about Perl and OpenVMS at this year's DECUS symposium which took place in Frankfurt. The slides which give quite some examples of the practical use of Perl in an OpenVMS shop may be found here.
  • Yesterday (06-FEB-2008) I gave a little talk at the University of Hamburg with the title "Faszination Analogrechnen". The slides for this talk are available for download here (ca. 2.9 MB).
  • Important: In the future all pages covering analog computing, its techniques, technology, application etc. will slowly be moved to a new location at http://www.analogmuseum.org. This is the result of the growing size of the collection and documentation and the wish to have a central point in the web to gather information about analog computing. Please note that the URL mentioned above will redirect you to FAFNER, my VAX, which may be a temporary solution, but the sheer amount of scans, pictures and videos has reached a dimension which exceeds the file space limits imposed by my provider, so it might be a permanent solution as well. Please tell me ( ulmann@vaxman.de) if you find any errors, broken links (the German pages are currently not very complete, so only the English pages are representative at the moment) or have suggestions. I hope you will enjoy the new structure and style of these pages (is the frame OK or do you think it is a NO-NO?).
  • Have you ever wondered who a rendezvous in space is performed when two space craft shall be coupled together like the CM/LEM or a Space Shuttle and the ISS etc.? If so, you might want to have a look at a simple orbital rendezvous simulation I programmed this weekend (12/13-JAN-2008).
  • On December 1st, 2007, I finished a more complex program on the Telefunken RA 770 analog computer to display a so called Joukowski airofoil with lines of airflow around this profile. The first video clip (about 8 MB!) shows a single line of airflow around this airofoil under manual control while the second video clip (about 2 MB) shows the automatic generation of a family of 16 curves using the very same program which is described in more detail here.
  • About two weeks ago, one of the dreams of my childhood came true: I got a Telefunken RA770 analog computer - one of the finest systems ever made (IMHO).
  • A couple of days ago I reimplemented the vehicle simulation listed below on my EAI 580 analog computer using no special external equipment like the four channel oscilloscope multiplexer, etc. This was possible since the EAI 580 features quite a few electronic analog switches which can be employed to implement a display multiplexer on the computer itself. This new simulation is more realistic than the old one below and shows the car frame, the wheels and the road itself in motion. Read more about this simulation here.
  • On September 22nd, my friend Dr. Karina Schreiber (a mathematician, too) came for a visit and we had lots of fun creating some artwork using an analog computer. Some of the pictures we created can be seen here.
  • Thanks to Mr. Böhringer from the Universität Karlsruhe you can find here a so called "Studienarbeit" describing the development of a control system to implement a magnetic suspension (a hovering metal ball :-) ) - about 3.3 MB.
  • Last weekend I developed a small analog computer program to display rotating three dimensional figures on an oscilloscope screen - this program together with a short movie of a rotating spiral can be found here.
  • On 29-APR-2007 my wife and I were invited by Prof. Dr. Meyer-Brötz, the father of the first transistorized analog computers made by Telefunken. His first two machines were the RA 800 and the RAT 700, developed in 1959/1960. Prof. Dr. Meyer-Brötz left the area of analog computing in 1966 when he realized that digital computers would eventually supersede analog computers in terms of computing power. His interests shifted to electronic character recognition and the like in the following years. It was a wonderful experience and a gift to meet him and his wife in person. He has lots of memories of the time of his analog computer developments at Telefunken and is a truly wise man. This picture was taken by his wife at the end of our visit. He sent it to us with this short handwritten note.
  • In a rather sleepless night I wrote a small, but quite useful program to factor numbers on the TI-59 which can be found in the example programs section of my TI-59 page.

    And I wrote a small page about the HP-28S pocket calculator, one of my absolute favourites. This page contains a clock program as well as a handy routine for playing with the Ulam series (more to come, I think).

  • With several weeks of delay I eventually found the time to write a bit about my (succesful) repair of a wonderful HP 67 programmable pocket calculator including some hints on repairing the built-in card reader/writer.
  • Since today was such a beautiful day that even I decided to go out for a walk with my wife, I began thinking about measuring distances using a modulated diode laser while walking with her. This led to the development of a very simple TTL modulated diode laser which I built the very same afternoon after we came home.
  • At this year's VCFE in Munich I bought a HP 41C pocket calculator - a machine I dreamed about when I was 13 or 14 years old. Since the calculator was not working, the page linked to above describes how I repaired it.
  • Today I prepared some slides for this year's VCFE taking place in Munich from April 29th to April 30th 2007. These slides describe my favourite programmable pocket calculator, the TI-59.
  • Today I prepared some slides for this year's VCFE-8.0 taking place in Munich from April 29th to April 30th 2007. These slides describing the well known bouncing ball in a box at greater detail.
  • The TI-59 page now contains a second example program to perform decimal -> binary conversion and vice versa.
  • In reminiscence of the 30th birthday of my favourite programmable pocket calculator, the TI-59 I begun a page describing and celebrating this work of art.
  • Last year (2006) I started the design and development of yet another homebrew processor, a simple but elegant 16 bit architecture called QNICE. A slide set describing the machine can be found here.
  • At the IT Symposium 2007 I will deliver a talk covering database proxies written in Perl. The slides for this talk can be found here.
  • At this years Vintage Computer Festival Europe I will deliver a talk about one of my favourite programming languages, APL.
  • The analog computer simulation of a two mass vehicle suspension system has been considerably extended by a detailed description of the computer circuit and the basic differential equations which were derived for this problem.
  • Today I programmed a (simplified) car suspension system simulation on one of my Telefunken analog computers. The page describing this small project contains links to three worthwhile AVI-files showing the overall setup of the simulation and the output of two simulation runs performed with different parameters.
21-JAN-2007 A lot of simulations and stochastic computations require a very good low frequency random noise source. Using a commercial random noise generator like the Wandel und Goltermann RG-1, this special filter delivers a very narrow band low frequency signal suitable for analog computation.
  • Since we (Rikka and I) were invited to a new year's party which required all of the participants to give talks about paranormal phenomena and the like, I decided to talk about the random number generator experiment which was conducted in 1998. The slides for this talk can be found here.
  • Here you can find the description and schematics of a (rather simple) control stick adapter to be used in conjunction with an analog computer. Having a control stick connected to an analog computer is an invaluable tool for man in the loop simulations where someone has to control some simulated device like a spacecraft, etc.
  • The OMS 811 pages have been updated with six additional pictures showing the various printed circuit boards of this wonderful dual channel X/Y-oscilloscope.
  • A few weeks ago I bought another OMS 811 oscillocope which was in need of some restoration and repair. A short story of this restoration can be found here.
  • Mr. Bruce Baker, a former employee of Martin-Marietta and analog computing kindly scanned some pictures and papers related with his work on aerospace simulation using analog computers.
  • Thanks to Heribert Müller who lend me the Bedienungsanleitung for the EA-22 analog computer manufactured by the small company GTE, you can download it here as a 17 MB pdf-file (in German).
  • Lots of new detail photos of the Dornier DO 80 analog computer.
  • The MEDA 43 analog/hybrid computer. This machine was designed and built in the former czechoslovakia and found widespread use in the countries behind the iron curtain.
  • The EAI TR-10 analog computer. This is the first transistorized table top analog computer built by EAI (1961).
  • On 29-MAY-2006 my wife and I had the pleasure to have Prof. Giloi with his wife and Prof. Lauber with his wife as our guests. Some photos of this event which was very significant for me can be found here.
  • Bringing Seismic Data to the Web with OpenVMS, slides (about 1.4 MB) for my talk covering the usage of LAT-devices for the transmission of binary data from a seismometer system to an OpenVMS system, etc. This talk was given at the DECUS-Symposium 2006 in Düsseldorf, Neuss.
  • Bringing Vegan Recipes to the Web with OpenVMS, slides (about 300 kB) for a talk given at the DECUS-Symposium 2006 in Düsseldorf, Neuss. This talk covered a Perl based database proxy for RDB on OpenVMS as well as the benefits of the RTE technology of the WASD web server for OpenVMS to speed up the execution of CGI scripts and a lot of other topics like an intelligent method to bulk copy data from a MySQL system to a RDB database, etc.
  • Workshop - Analog Computing - slides covering the solution of three typical problems on an analog computer in detail. These examples are 1) mass-spring-damper system, 2) Lynx/Rabbit ecosystem and a 3) bouncing ball in a box. These slides (about 700 kB) were prepared for a talk to be given at the VCFE 7.0 2006 in Munich.
  • 17-APR-2006
    • Added some remarks about building an analog computer using modern parts to the Analog Computing page (below the documentation part).
    • After three days of hard work I got my TELEFUNKEN RA741 analog computer up and running again - about 30 years after the system had been sitting in various storage locations.
    • Programming a bouncing ball in a box - this link leads to a page showing the overall program, setup and an AVI-file showing the bouncing ball.
    • All of the scanned documentation is now available via ftp, too. The ftp-server is fafner.dyndns.org. It supports anonymous ftp; do not forget to switch to binary mode prior to get-ting pdf documents. Please note that FAFNER is connected to the internet by a simple DSL line so upstream bandwidth is very limited. Please do not attempt to fetch all documents at once!
    • I have been busy during the last weekend and built a small speech synthesizer for my VAX FAFNER - you may find more information about this device, including the complete schematics, on the Dragontalk page.
    • Hybrid Precision Analog Computer System RA 770 D, Operating Manual, Part 1 (English, about 6 MB, 40 pages) and Part 2 (English, about 19 MB, 75 pages).
    • A short operating guide for the RA770 analog computer (in German) which is based on a thesis written by R. Aderhold: Kurzgefasste Bedienungsanleitung für den Telefunken Analogrechner RA 770 , about 3 MB.
    • Thanks to my friend Hans Kulk who sent me a copy of the following, you can now download the complete TELEFUNKEN ZEITUNG, Jahrgang 29, 1966, Heft 1, Herausgeber Prof. Dr. W. T. Runge (German, about 17 MB!). This wonderful publication describes the development of a high precision operational amplifier as used in TELEFUNKEN's analog computers, it covers the RA 800 Hybrid, describes in detail the technology of function generation, etc. A truly remarkable publication and a must read for anyone interested in analog computing.
    • Thanks to my friend Christian Peters who worked hard for many hours the wonderful EAI lecture Understanding the ANALOG/HYBRID Computer is now available as podcast including audio and synchronized video (slides :-) ) here (about 17 MB). If you are interested in the audio data only, you can find a 16 MB mp3 coded file here.
    • A new page describing some General Dynamics analog computer modules which have been used in the control of a nuclear power plant.
    • Handbook for the OMS811 oscilloscope, in German, about 1 MB.
    • I found a wonderful picture from 1965 showing a TELEFUNKEN RAT700 analog computer simulating the suspension system of a car. This picture is shown on the page mentioned above or can be retrieved here.
    18-JAN-2006 Thanks to Mr. Thomas Proell who scanned the document "Technisches Handbuch", it is available here for download: