The B-7971 is a very large neon-filled alphanumeric display tube manufactured by Burroughs. Unlike ordinary Nixie tubes, which contain cathodes in the shape of symbols arranged on a stack, the B-7971 features 14 individual wire segments that can be combined to display every letter of the English alphabet in addition to digits 0 through 9. An additional segment in the bottom can be used to display an underscore. As opposed to the typical 16 segments found in most alphanumeric displays, the B-7971 only has a single segment in the top and bottom of the display area.

The HB-105 is a so-called Pixie tube manufactured by Burroughs. Unlike a Nixie tube, which forms numerals from a stack of digit-shaped cathodes, the Pixie tube uses a single anode plate perforated with digit-shaped holes, through which a neon discharge can be seen. The tube’s datasheet lists its various supposed advantages over Nixie tubes which included the ability to display multiple digits simultaneously and its low operating current. Additionally, it was significantly cheaper than conventional Nixie tubes at the time.

The OmniRay SAO M 40 is a so-called Sphericular Optic Display. While similar in both appereance and operation to projection displays like the IEE one-plane readout, the theory behind the M 40 is vastly different. It employs the principle of geometric optics to produce a character on a flat viewing screen. The screen area is subdivided into more than a thousand tiny convex lenses, each focusing light from its specific focal plane. Characters are displayed by illuminating only certain sections of the screen from different angles, which selectively allows light to pass through areas, producing a character composed of many tiny dots. A comprehensive explanation of the operational theory behind this device is available in the description of a similar model manufactured by Burroughs, accessible via the link provided below.

The E1T is a decadic counting tube developed by Philips which predates the invention of gas-filled Dekatrons. Each pulse advances the tube’s internal count by one and generates a voltage spike, which can be used to trigger external actions such as advancing the next stage of a multi-tube counter. Internally, the E1T operates as a small cathode ray tube with a ribbon-shaped electron beam that occupies one of ten stable positions. The current position of the beam is indicated as a glowing strip, with each position marked with its corresponding value on a piece of film affixed to the tube’s glass envelope. The tube’s envelope is coated with a transparent protective layer, which is prone to cracking over time, particularly in damp environments. Consequently, E1Ts in pristine condition have become increasingly rare.

The Z565M is a neon-filled decadic display tube manufactured by RFT in East Germany. Although it resembles a Dekatron, it lacks any kind of counting capability. Unlike the ZM1050/Z550M, it also cannot be controlled using logic-level signals. Instead, it operates more like a regular Nixie tube and is soemtimes referred to as a “Register tube”.

It features ten wire-formed cathodes arranged in a circle around a common anode. One or more cathodes can be ignited by connecting them to ground. When viewed from the front, the tube shows two empty holes between each cathode. In a full Dekatron tube, these positions would have been occupied by the transfer electrodes. To ensure consistent ignition regardless of ambient light or background radiation, the Z565M includes a small amount of radioactive material to improve the rate of spontaneous ionization of the neon gas.

The MG-19B is a tiny, segmented neon-filled display tube produced by Rodan and marketed under the Elfin brand, designed for use in small electronic instruments. It features two additional diagonal segments, enabling it to display the digits ‘1’ and ‘7’ more naturally, as well as certain other alphanumeric characters. The tube also includes a right decimal point. Unlike Nixie tubes, each cathode in the MG-19B requires an individual resistor, as the current needed varies with the number of illuminated segments. With a 180V breakdown voltage and a recommended 230V anode voltage, the tube operates at significantly higher voltages than most Nixie tubes. This made driving the MG-19B more complex, as affordable high-voltage transistors were not readily available when the tube was introduced.

When the Nixie tube was introduced in the 1950s, it faced a significant drawback: its driving circuitry required transistors with relatively high breakdown voltages capable of handling the elevated operating voltages necessary to drive them. At the time, such transistors were not readily available. This limitation created a demand for an alternative display technology that could be operated with low-voltage, low-current logic circuitry. The solution was the Z550M, which was later renamed to ZM1050.