Technologies Used in Old Computer Monitors | Let’s find out

Technology Used in Old Computer Monitors

Since their inception computer monitors have come a long way. Now we see higher resolution, flat panel, 4K OLED monitors which give very high-quality sharp images.

But we have not got these modern monitors directly. They have derived from the research done for decades after decades on technologies used in old computer monitors.

In this article, we will walk you through the technologies that were used in the old computer monitors and will discuss their unique characteristics and limitations.

Technologies used in old computer monitors

Mechanical Displays

Mechanical displays are also known as Nibkow displays as it is invented by Paul Nibkow in 1884. It is a kind of display technology that utilizes a series of spinning disks to generate visual graphics.

The basic principle of this technology is actually simple. Here a string of disks with tiny holes in them is mounted in a motorized spindle. As the spindle rotates, light flashes through the holes in the disks and is projected over a screen. By controlling the shape, size and location of the holes precisely, it generates a broad range of optical patterns and pictures.

One of the main benefits of this technology is that it can generate very high-resolution images. As the disks can be made very small, it is possible to generate images with more precision in this technology. This could not be achievable by other display technologies of that era. This made mechanical displays very convenient to use for early television systems.

However, this system also had significant drawbacks. One of them is this system needs a high level of mechanical accuracy to work properly. In fact, a slight alteration in the size and location of the holes on the disk can have a substantial effect on the image quality.

Another limitation of mechanical displays is their slower refresh rate. This is because here the disks have to rotate to create each frame of the image, it becomes impossible to display pictures at the same rate as other display systems like CRT or LCD screens. This makes mechanical displays unsuitable for applications where fast-moving images or video is required.

Mechanical displays

Oscilloscope Displays

An oscilloscope is an electronic test equipment that allows the visualization and analysis of varying signal voltages, generally as a two-dimensional graph where one axis represents time and the other represents voltage. Though it was not dedicatedly engineered for computer display but was used in computers to display information.

Though oscilloscope displays used cathode ray tubes (CRT) to generate pictures but they work differently from a conventional CRT monitor. In an oscilloscope, the CRT discharges an electron beam that is diverted by magnetic or electric fields which causes it to trace a path over the screen. The electron beam stimulates the phosphor particles on the screen, which creates a visible, luminous trace that represents the signal being measured.

In an oscilloscope, the vertical axis generally represents the signal voltage and the horizontal axis represents the time. An oscilloscope can display a broad range of amplitudes and signal frequencies by shifting the voltage scale and the time base.

In the early days of computers, oscilloscopes were utilized to see the output of computer programs and to fix hardware and software issues. Early computers like the Electronic Delay Storage Automatic Calculator (EDSAC) and the Manchester Mark 1 utilized oscilloscope displays for this application.

Oscilloscope displays had several drawbacks too. They could not produce detailed images and the screens could only display a single color. Moreover, the screens were not engineered for rendering text or graphics, which made them comparatively less suitable for many computing works.

Teletype Displays

Teletype displays are also known as teletypewriters or teleprinters. They are electromechanical devices that enable the transmission of typed messages over long distances through telegraph or radio signals. Prior to the arrival of modern computer displays, they were extensively used for communication applications.

In a teletype, there is a typewriter-like keyboard that is used for input and a printer is used for output. When a user types on the keyboard, the teletype encodes the keystrokes into electrical signals that can be transmitted over a telegraph or radio line. Another teletype decodes the signals at the receiving end and prints the text on a roll of paper, giving the data a “hardcopy” display.

Teletypes can work in a networked setting, where several teletypes are linked to a central computer or switch, or in a point-to-point structure, where one teletype connects with another teletype directly.

Teletypes were frequently utilized as input/output devices for computers in the early days of computing. They gave users the ability to input data or commands into the computer and get output in the form of written text. Teletypes were frequently employed as the main user interface for early computers like the UNIVAC I and the IBM 701.

With the progress of computing, teletype displays gradually became obsolete. It became increasingly insufficient for the needs of computer operators. Some of its key limitations are:

Slow output speed: Teletype displays used mechanical printing. That’s why they were much slower than electronic displays.

Noisy Operation: As the teletype system was mechanical in nature so they used to make a lot of noise in their operation which was annoying for many users.

Limited display capabilities: Teletypes were only capable to display text. It had no support for graphics or diverse font sizes and styles.

Paper usage: It was not environmentally friendly to use paper for output. Moreover, it was also very difficult to manage huge amounts of printed data.

Because of their limitations, teletype displays were ultimately replaced by electronic displays, like CRT monitors, and later by flat-panel displays as they offered faster output, more advanced graphical capabilities, and quieter operation.

Other Old Monitor Technologies

Cathode Ray Tube (CRT) Monitors

The CRT monitor was the most famous and widely used computer monitor of the past. After the invention of CRTs in the late 19th century the CRT monitors served as the primary display technology until the early 21st century.

CRT monitors comprised a phosphorescent screen, an electron gun, and a vacuum-sealed glass tube. A beam of electrons is emitted by the electron gun, which strikes the phosphorescent screen and generates light, and displays images.

There are several benefits of a CRT monitor which include high refresh rates, low input lag, and excellent color accuracy. But like any other thing, it definitely comes with its drawbacks like huge size, heavyweight, and high-power consumption. Moreover, a substantial amount of radiation is emitted by the CRT monitors which has a negative effect on human health.

Technologies used in old computer monitors

Monochrome Displays

Monochrome displays are single-color displays. Before the usage of color displays was established as a tradition, many people used monochrome displays on their computers.

Monochrome monitors usually displayed text and simple graphics in a single color (usually green, amber, or white) against a black background. Due to their comparatively cheaper price and low power consumption, they were popular in the early days of computers.

One of the best examples of monochrome displays is the IBM 5151, which came into the market in 1981. This monitor had a green phosphor screen and became the standard for IBM’s personal computer line. Though it was popular for quite a long time but it eventually became obsolete as the color displays became quite affordable and capable of displaying a broad range of colors and higher resolutions.

Electroluminescent Displays (ELDs)

Though electroluminescent displays were never as widespread as other display technologies but they were used in some early computer monitors and portable devices. ELDs are made of a thin film of phosphor material sandwiched between two electrodes. When an electric current is applied to the electrodes, the phosphor material emits light, creating an image.

There are multiple benefits of this technology like low consumption of power, light and thin designs, and phenomenal contrast ratios. However, their problem was that their brightness was low and they had relatively low resolution. This made them less convenient for general-purpose computer monitors. ELDs were mainly used for specialized purposes, such as military hardware and industrial control panels.


Now we have seen the technologies used in old computer monitors have laid the foundation for modern computer displays.

Every technology progresses with time. Computer monitors are no different from this.

We will always continue to push the boundaries of display technology making them more advanced, cheaper and versatile.

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