On/Off button with USB interface based on Arduino. Includes links to information about HID.

Keep accurate time on a Linux machine based on radio time signals such as DCF77, MSF or WWVB. Found via https://packages.debian.org/stable/net/radioclk
It uses the modem control input signals to monitor the signal from the radio receiver. For a Raspberry pi, where I want to use this, the articles
"Raspberry Pi RTS / CTS Flow Control" https://ethertubes.com/raspberry-pi-rts-cts-flow-control/ and
"Raspberry Pi 3 Hardware Flow Control"  http://www.deater.net/weave/vmwprod/hardware/pi-rts/ will be useful.

Found via a comment on https://github.com/excalidraw/excalidraw

Recently a DCF77 receiver and decoder program based on Python and GNU Radio has been uploaded to GitHub
https://github.com/henningM1r/gr_DCF77_Receiver
by henningM1r. It includes a simulator written in Python so you can simulate your own DCF77 signal for testing the receiver too.

Currently the decoder has been tested to work with an Airspy HF+ Discovery SDR, but it should work with any SDR capable of receiver 77.5 kHz if the GNU Radio source block is changed out.

gcalcli is a Python application that allows you to access your Google Calendar(s) from a command line. It's easy to get your agenda, search for events, add new events, delete events, edit events, see recently updated events, and even import those annoying ICS/vCal invites from Microsoft Exchange and/or other sources. Additionally, gcalcli can be used as a reminder service and execute any application you want when an event is coming up.

gcalcli uses the Google Calendar API version 3.

Found on https://www.raspberrypi.com/news/pico-powered-progress-bar/

gLAB is a software tool suite developed under an European Space Agency (ESA) Contract by the research group of Astronomy and Geomatics (gAGE) from the Universitat Politecnica de Catalunya (UPC), is an interactive educational multipurpose package to process and analyse GNSS data.

gLAB performs precise modeling of GNSS observables (pseudorange and carrier phase) at the centimetre level, allowing both standalone GPS positioning and PPP. Every single error contributor may be assessed independently, which, in turn, provides a major educational benefit. gLAB is adapted to a variety of standard formats like RINEX-3.00, SP3, ANTEX and SINEX files, among others. Moreover, functionality is also included for GPS, Galileo and GLONASS, allowing performing some data analysis with real multi-constellation data.

The gLAB software tool is quite flexible, able to run under Linux, Windows, and Mac operating systems and is provided free of charge by ESA Education Office to universities and GNSS professionals.

Found on https://gssc.esa.int/navipedia/index.php/GNSS:Tools

Documentation and description of projects using Inmos Transputer processors.
Found via a link on http://www.chilton-computing.org.uk/inf/transputers/overview.htm

Explanation of GNU epsilon https://www.gnu.org/software/epsilon/epsilon.html
"The ε core language, an imperative first-order language, is called ε₀. It’s inconvenient for humans to use for serious problems, yet simple and potentially very efficient. Using ε₀ I’ve built ε₁, a higher-level language with a Lispy feel, but untyped — not dynamically typed like Lisp: untyped, like Forth and machine language."

See also https://ageinghacker.net/blog/posts/33/ for make-gallery, a bash script to generate a HTML photo gallery.

Found via a comment about calc http://www.isthe.com/chongo/tech/comp/calc/index.html
on https://groups.google.com/g/comp.lang.tcl/c/7JXGt-Uxqag/m/rcHDLLu6MpEJ
See also https://www.systutorials.com/docs/linux/man/1-calc/ for a man page.

Document explaining the development of a bc/dc clone. Might be a good example to follow, if I ever make a public project.