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DRS - TCQ-350

The TCQ-350 is a TEMPEST-shielded PC, manufactured by US-Defense contractor DRS Technologies Inc. in Columbia (USA) around 1997 as part of the TCQ series. It was sold in Europe by DRS in the UK. The machine was intended for highly classified computer use, such as cryptography, and was a NATO-recommended product [1]. It is no longer in production.

At the heart of the computer is a Compaq EN motherboard with a 450 MHz (or higher) Pentium II processor with suitable memory and an AGP video card. For storage, an internal IDE harddisc was present, alongside a shielded floppy disc drive. External storage was possible through the built-in SCSI interface.

The image on the right shows a typical TCQ-350 machine with its protective door open showing the built-in CD-ROM drive. At the left is the shielded floppy disc drive. From the unit shown here, the top lid has been removed.
Typical view of the DRS TEMPEST PC TCQ, with top cover removed and the door open.

Connecting a PC to a network (e.g. Ethernet and/or the internet) is always a safety risk, especially when operating in a secure environment. For this reason, the TCQ has a built-in Optical Fiber interface, which isolates the built-in 10/100 Mb ethernet interface galvanically from the network. This avoids unwanted leakage of information to the outside world (side channel leakage).

The computer is housed in a sturdy case which is heavily shielded. The top lid is held in place by a large number of screws, and a series of metal contact strips is used to ensure that the case is 'air tight' from an HF point of view. This is done in order to avoid unwanted eminations, such as HF radio signals 'escaping' from the case (TEMPEST), potentially giving away sensitive information.

In order to protect the data inside the computer and any possible cryptographic keys, the machine has a built-in tamper switch which is held down by a stub in top lid. Whenever the top lid is removed, the tamper switch is activated and the software can take appropriate steps.

DRS produced TEMPEST PCs and rugged laptops from the mid-1990s to the early 2000s. Over the years, different versions with faster processors and more memory were produced. In 1999, DRS secured an order from the US Department of Defense (DoD) for the production of TEMPEST PCs based on the Sun UltraSPARC2 [2]. DRS is still in business today (2011) and produces a wide range of equipment for the US Department of Defense [3].

Typical view of the DRS TEMPEST PC TCQ, with top cover removed and the door open. Floppy disc drive Shielded floppy disc drive Interior Optic Fibre interface Close-up of the tamper switch inside the computer Tamper switch stub Power socket and Fibre Optic connections
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Typical view of the DRS TEMPEST PC TCQ, with top cover removed and the door open.
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Floppy disc drive
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Shielded floppy disc drive
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Optic Fibre interface
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Close-up of the tamper switch inside the computer
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Tamper switch stub
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Power socket and Fibre Optic connections

  1. NATO/SECAN, NATO Recommended Product List (NRPL)
    January 2007.

  2. Business Wire, DRS Technologies Awarded $1.3 Million Contract... Produce New TEMPEST Computers for Department of Defense
    8 November 1999.

  3. DRS Technologies website
    See also: DRS Tactical Systems
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Crypto Museum. Created: Monday 13 May 2013. Last changed: Wednesday, 28 February 2018 - 20:23 CET.
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