Remember the days before everyone had a mobile phone? Although it s hard to imagine these days, but back before everyone had a mobile phone, public payphones and public phone booths were a massively important part of public infrastructure as a form of primitive mobile telephony for making phone calls. But what about data? Although the [ ]
One of the things that people love talking about these days is technical debt. This is usually treated as a bad thing, as if it would not occur if only we had been more attentive during our design or programming stages, or spent more time getting better specs from our clients. This is then accompanied [ ]
One of the foundations of computer code is the humble loop. Going back at least as far as the beginning of C in the early 1970s, the two mainstays of loops in procedural languages have been the while and the for loop. Unfortunately, I think it s fair to say that they also contribute to the [ ]
One of the topics that people like to talk about is technical debt. However, when you actually get into what creates this technical debt, you find a lot of simple repeating patterns that reduce code readability. So, I decided to run through a pile of them to see if there are any simple fixed. The [ ]
The easiest way to understand the current state of encodings is to look at the history of how we got to where we are today. The pre-ASCII days are not particularly relevant, but they are interesting, so I have run through the various encodings that preceded ASCII from a technical perspective here if you are [ ]
While various flag and signal based encoding systems have existed since pre-history (signal fires, smoke signals), true digital encodings were not needed until attempts to communicate via electrical signals in the form of the electromagnetic telegraph. The early telegraph systems in the 1830s and 1840s were extremely limited in terms of electric components, with basically [ ]
It s 1887. The only electrical components you have access to are electromagnets. And you want to build a digital to analog converter. What do you do? The answer is simple. Run a string along the ends of a series of electromagnets, and arrange pulleys connected to these magnets so that each successive magnet pulls twice [ ]
This device is somewhat of a revolution in telegraph technology from the 1870s. It uses a fixed-length 5-bit binary encoding, the kind of encoding that we would expect to see in silicon-based electronics equipment. Baudot created a receiver that resembles a mechanical computer to perform the decoding and printing. Looked at in modern terms, it [ ]
Here is one of the early patents for electroacoustic multiplexing of telegraph signals. (Note that this is not the same as electroharmonic multiplexing, which used multiple frequencies as carrier waves to achieve multiplexing.) I like this one because it really shows the acoustic component of the system. Here is a picture of a quadruplex system. [ ]
This is an early attempt at an isochronous distributor-based multiplexing telegraph from 1873. It demonstrates the problematic nature of using Morse code with this kind of multiplexing system. First, let s have a look at the top view of the device. It looks like a bit of a mess. So here s a color-coded version for describing [ ]