[WaveDrom] is Free and Open Source online digital timing diagram (waveform) rendering engine that uses javascript, HTML5 and SVG to convert [WaveJSON] input text description into SVG vector graphics.

[WaveJSON] is an application of the JSON (JavaScript Object Notation) format. The purpose of WaveJSON is to provide a compact exchange format for digital timing diagrams utilized by digital HW / IC engineers.

WaveDromEditor is online real-time editor of digital timing diagrams based on [WaveDrom] engine and [WaveJSON] format. The engine using [WaveDromSkin] skin mechanism to render complete picture. Multiple timing diagrams can be embedded into your HTML page as described in [WaveDromPlugins].

GNU SRC (Source Release Collection) provides a simple way to install the latest officially released versions of GNU packages on an existing distribution
The aim is to make it easier to work with sources, and to help with development and bug reporting.

If you need to convert files from one markup format into another, pandoc is your swiss-army knife. Pandoc can convert documents in markdown, reStructuredText, textile, HTML, DocBook, LaTeX, or MediaWiki markup to

HTML formats: XHTML, HTML5, and HTML slide shows using Slidy, Slideous, S5, or DZSlides.
Word processor formats: Microsoft Word docx, OpenOffice/LibreOffice ODT, OpenDocument XML
Ebooks: EPUB version 2 or 3, FictionBook2
Documentation formats: DocBook, GNU TexInfo, Groff man pages
TeX formats: LaTeX, ConTeXt, LaTeX Beamer slides
PDF via LaTeX
Lightweight markup formats: Markdown, reStructuredText, AsciiDoc, MediaWiki markup, Emacs Org-Mode, Textile

ditaa is a small command-line utility written in Java, that can convert diagrams drawn using ascii art ('drawings' that contain characters that resemble lines like | / - ), into proper bitmap graphics.

Tangle is a tool to help you document networks. It generates HTML documentation including diagrams from a text file listing network devices.

Web simulation of a slide rule.

gmeteor is a tool for designing discrete-time equiripple filters with linear phase and a finite impulse response (FIR). With gmeteor, you can design filters with an arbitrary frequency response. `gmeteor' runs on systems that support the Guile extension language from the GNU project (for example, GNU systems running on a Linux kernel). `gmeteor' is free software distributed under the terms of the GNU General Public License (GPL).

Java program to compute transits (conjunctions) of a satellite and sun, moon or a planet.

Smart card to securely store up to 3 keys and use them via USB for gnupg, Truecrypt and some other applications.

Instructions to enable PDF viewing in Emacs under Windows.