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Circuit Blocks
Digital circuit blocks

Circuit Blocks were the forerunners of the modern Integrated Circuit (IC), developed around 1960 by Philips and manfactured by Philips (Netherlands), Mullard (UK) and Valvo (Germany). The small modules are brightly coloured and have a number that indicates its function. In fact, each module contains a small printed circuit board (PCB) with conventional passive and active components.

Various series of Circuit Blocks appeared over the years, such as the 10-Series, 20-Series, 40-Series, Norbits 60-Series and the Input/Output Devices. The image on the right shows some examples of the Philips Series-1 (also known as 1-Series) that were introduced around 1960 [1].

Circuit Block were heavily used in professional and military equipment from 1960 to the early 1970s, but were eventually superceeded by the Transistor-Transistor-Logic (TTL) ICs that were introduced in 1967 and that were soon widely available. ICs eventually took over the market.

Similar devices, known as FLYBALL modules, were developed around the same time in the US. They were used in several high-level cipher machines of the era. Like the Philips ones, they were eventually replaced in the late 1960s and early 1970s by modern TTL ICs. In the former DDR (East Germany), similar building blocks were made by Keramischen Werke Hermsdorf (KME) [4].

Examples of brightly coloured Series-1 circuit blocks
Philips/Mullard/Valvo Series-1 Circuit Blocks
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Examples of brightly coloured Series-1 circuit blocks
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Philips/Mullard/Valvo Series-1 Circuit Blocks

Example from a Philips publication of 1967 [2]
Examples of a Series-1, 10-Series and 20-Series module

Known series
Series-1   100 kHz series
Developed around 1960 and thought to be the first all-transistor encapsulated circuits [1]. Consisting of a brightly coloured plastic enclosure with a small PCB, covered in epoxy.

Each module had 10 wires, which extend from the module on one of the longe edges. The internal circuit is built around unbranded OC47 transistors — a general purpose PNP germanium transistor, made by Philips for OEM purposes — and is specified for a speed of 100 kHz.

10-, 20- and 40-series
These series were developed around 1969 and have the same physical dimensions as the 1-Series, albeit with two rows of contacts, arranged in a zig-zag pattern, totalling to 19 wires.

These modules were housed in a plastic enclosure (available in several colours) with bended contacts extending from both long edges, in the same way as the later Dual-In-Line (DIL) packages, but larger. One side had 8 contacts, whilst the other had 9 [1]. Not much information about the NORBITs is available, but there seems to have been a NORBIT 2 and NORBIT S variant. Furthermore, NORBIT was available in a 60-Series, 61-Series and probably a 90-Series.


  1. Components and Materials, Part 1
    Philips Elcoma, September 1970.
  1. Andrew Wylie, Packaged circuits
    2009. Retrieved November 2017.

  2. E.J. van Barneveld, Digital circuit blocks
    Philips Technical Review, Volume 28, 1967, pp. 44-56.

  3. Wikipedia, Philips NORbits
    Retrieved November 2017.

  4. Robotron Technik (website), KME-Technik
    Retrieved November 2017. 1
  1. Thanks to Jörgen Drobick for bringing this to our attention.

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Crypto Museum. Created: Tuesday 28 November 2017. Last changed: Tuesday, 15 February 2022 - 08:07 CET.
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