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Microdrive, IBM DSCM-11000, with 1GB capacity. From year 2000. Connector type is “CF+ Type II”. Formfactor 1.8’’. Weight 16 gramms. These are real harddiscs, with super-small rotating discs inside, moving heads and all that fancy stuff. This was designed at a time, where it was not possible to create large semiconductor based non-volatile memory. At that time, it was easier to scale down the physics of a real harddrive and to create a tiny version of that.

PDP11 Assembler This text describes how to assemble PDP11 files on Linux. MACRO-11 assembler, linker, disassembler for Linux There are several ways to create object binaries for PDP11 on Linux. I have tested these tools that form a nice tool set for handling PDP11 assembler files on Linux: Macro-11 Assembler, see https://github.com/andpp/macro11 (written in C) Macro-11 Linker, see https://github.com/andpp/pclink11 (Written in C++) PDP-11 Disassembler, see https://github.com/caldwell/pdp11dasm (Written in C) All tools did compile without any options by just executing make on them.

Coding for PDP11 machines without any target operating system (bare metal). Gnu GCC does the job. Github location There is useful code on Github, see here: https://github.com/DennisD2/pdptools/tree/main/all2deposit Toolchain install https://www.teckelworks.com/2020/03/c-programming-on-a-bare-metal-pdp-11/ https://xw.is/wiki/Bare_metal_PDP-11_GCC_9.3.0_cross_compiler_instructions # Download packages curl https://ftp.gnu.org/gnu/binutils/binutils-2.34.tar.gz >binutils-2.34.tar.gz curl https://ftp.gnu.org/gnu/gcc/gcc-9.3.0/gcc-9.3.0.tar.gz >gcc-9.3.0.tar.gz # Extract packages tar xvf gcc-9.3.0.tar.gz tar xvf binutils-2.34.tar.gz # Download/install prerequisites for compiler cd gcc-9.3.0/ ./contrib/download_prerequisites # Create build dirs cd .. mkdir binutils-build mkdir gcc-build # Build binutils cd binutils-build/ .

If you want to write code for a PDP11 CPU or PDP11 machine, you need some environment to do so. I have only parts of a PDP11 machine and cannot simply use this to write code. So I tried several ways: Using SIMH emulator to emulate a PDP11 machine, boot up some PDP11 Operating System (RT11) and use the available tools from that OS Using native Linux executables that allow for assemble and link valid PDP11 executables Using Gnu GCC toolchain for bare metal programming The SIMH emulator way is described in this document further below.

Für Freunde des guten Klangs, insbesondere bei Plattenspielern, ist Dual ein Begriff. Wie ich in Foren gelesen habe, sind die alten Dual Plattenspieler einem Neugerät normalerweise an Qualität überlegen, bis zu einer Neugerätmarke von rund 500 Euro. Erst dann bekommt man was Besseres. Ich persönlich würde daher immer einen Dual, oft für ein paar dutzend Euros, nehmen. Und tatsächlich sind diese circa 50 Jahre alten Geräte heute oft noch in sehr gutem Zustand, mechanisch robust, elektrisch dauerhaft hergestellt.

Below I’ve experimented with gnuplot, in few examples: Reading and displaying data from a file Reading and displaying data from a GPIB-connected device (measurements from a voltmeter with open input connection) Reading and displaying data from a GPIB-connected device (measurements from a voltmeter connected to a 10 volts voltage reference) gnuplot is a nice tool for plotting data. Start gnuplot to enter plot commands. I tried this tool when analyzing a strange behaviour of a Zener diode.

5 1/2 DMM from the 80ies. It has a hidden 6 1/2 digit mode. My meter does not have the True RMS module for AC. But it has a connector that emits the measurements via RS232 (not tested). While all date codes from the digital board are from 1984, I found also some chips from 1988. So the meter is from 1988 or later. It looks like the meter was in “official” use until 2023, because there is a safety sticker from this year.

ITT teddy 4 came as not working together with another radio I bought from an ebay seller. This radio is from early seventies, I estimate. The radio is medium-sized, not a small one, but also not a large one. Sound is quite impressive, it has more bass than I expected. Sound, compared to e.g. ITT Junior automatic, is much better. This picture was done after repair and cleaning all caging parts.

I wanted to replace a 4x1,5 volts baby cells power arrangement in an old radio ITT teddy 4. New battery should be the ubiquitous 18650 cell. It offers about 4.2 volts, so I looked for a solution that does up conversion to about 6 volts, and that offers a USB connector to load the cell. Best would be to have also some battery protection (undervoltage protection, current overload protection). I found two interesting modules for further analysis.

This is a great DMM from the around 1979. It is called “Microvolt Digital Multimeter” because it has a resolution down to 1 microvolt. Even more interesting is the current range, going down to 1nA (nanoampere) resolution. This is due to the DC range 20 mV (20.000mV) and DC current range 20 µA (20.000µA). Finally, it has a 1mOhms resolution on 20.000 Ohms range. This multimeter is great to measure small currents, e.