Philips MDT →
Mobile Data Termial
The MDT-9100 was a mobile data terminal, developed by Motorola
(USA) during the 1980s, as one of the successors to the
D-1118. The units were developed for use by emergency
services and were built into police vehicles. Several versions
of the 9100 were introduced over the years.
The device consists of a rugged plastic enclosure with a built-in amber CRT
screen, a relatively small processor board (CPU) and a compact keyboard
at the front. The screen is 30, 40 or 80 characters wide and 24 or 25 lines high,
and is used to the display messages sent by dispatch.
Although Motorola advertised the MDT-9100 as a secure data terminal,
it was in fact insecure, as the data was not encrypted at all. In 1996,
this problem was solved by
Philips Crypto BV in Eindhoven (Netherlands), who
developed a high-end secure mobile encryptor
for the MDT-9100.
The Philips solution took the form of a PCMCIA card, as a result of which
it was only suitable for the MDT-9100-386 and the MDT-9100-T.
The image above shows a typical MDT-9100-WS as used by the Dutch
Police in the city of Eindhoven — the only customer of the Philips solution.
MDT-9100 became a popular mobile terminal and was used by many police
forces around the world, well into the 2000s and in some countries even as late
as 2010. In the Netherlands, the Motorola MDTs were phased-out when the
new nation-wide C2000 network was rolled out .
was a digital trunking system, made by Motorola and based on
the TETRA standard .
MDT in Amsterdam
Below is a 9-minute video that was made by the police of the city of
Amsterdam (Netherlands) at the introduction of the MDT . It shows how
time consuming verbal messages were replaced by the efficient mobile
data terminal, and how it could directly access a variety of databases .
The Motorola MDT-9100 of the metropolitan police in Amsterdam (Netherlands)
Over the years, different versions of the MDT-9100 were developed and
introduced. Although they all look the same, the interior of each model
is quite different. Furthermore, the text on the backlit keys was often
customised for specific needs or languages.
The known models are:
The first model (10) is fairly simple and can only be used in combination
with a base station. It does not allow messages to be prepaired off-line.
Models (T) and (386) are both based on a 386 motherboard and are in fact
mini PC's. They are the only models that feature PCMCIA expansion slots.
The latter could be used for memory expansion, a solid-state harddisc or
an external data encryptor, such as the highly secure
Philips MDT Mobile Encryptor
that was released in 1996.
The MDT-9100-T was the first device in the 9100 family that was based on
a 386 PC board. It is in fact a mini PC running the well-known AMI Bios
that is used to boot the Windows 3.0 operating system.
It has 4MB of RAM, but no harddisc. Instead it features a
non-volatile RAM (NVRAM) which acts as a flash-type harddisc.
It has two COM-ports (COM1 and COM2) and a parallel printer port.
A 15-pin port is used for the radio interface .
Further information below.
The MDT-9100-386 was a more advanced version of the MDT-9100-T.
In addition to the features listed above, the 386-version also had
a SCSI interface. There may be other differences, but we are currently
not aware of them. The 386-model became rather popular with many Police
agencies in the US, but also world-wide,
for example in The Netherlands.
The CRT-screen has a resolution of 80 x 25 characters, but can be made
to display larger text at 40 x 25 by using the appropriate DOS 'MODE'
For expansion, two PCMCIA card-slots are available at the right side.
The slots only accept old style 16-bit PCMCIA cards .
In 1996, Philips Crypto BV
in Eindhoven (Netherlands) developed a
PCMCIA expansion card for this model,
that added virtually unbreakable high-end cryptography to the unit (see below).
Although Motorola advertised the MDT-9100 as suitable for secure data
communication, the standard version was in fact highly insecure. Like its predecessors,
and the D-1118,
it used a fairly simple data protocol
that was easily broken by hackers in the 1990s .
According to Motorola, a 'special code' was used, but the code appeared
to be nothing more than plain ASCII.
The data protcol was known as the
and used bit-interleaving as a means to correct transmission errors,
and to obscure the data stream. When hackers discovered the properties
of the protocol, several PC programs appeared that allowed the general
public to monitor police conversations with nothing more than a scanner,
a PC and a simple interface .
In the US, the problem was 'solved' by making it illegal to publish and
use the PC-based hacking software. Although it helped the authorities
to take down most sources from the internet, it didn't prevent wide-spread
use of the software. As a result, many people were able to monitor
police conversations well into the 2000s, mainly because no real encryption
was used on these systems.
In The Netherlands, the MDT-9100 was used by the Police in the cities
of Amsterdam and Eindhoven. They both were aware of the
security risks involved, and knew that criminals were actively monitoring their
As a result, the Eindhoven Police Department teamed up with
Dutch crypto manufacturer Philips Crypto BV
in 1994, with the intention to develop a truly secure solution.
Eventually, this colaboration resulted in 1996 in a
PCMCIA card with high-end data encryption,
that could be installed in existing MDT-9100-386 terminals.
Initially, the Amsterdam Police would also be involved in the project,
but they pulled-out when they discovered that their MDT-9100s were not
suitable for the expansion, and no budget was available to replace the
existing terminals. Despite its high potential, Philips never managed
to sell the system world-wide.
Eventually, Eindhoven would be the only city to use this solution.
➤ More about the Philips MDT crypto card
The history of the Motorola MDT-range dates back to the late 1970s,
when Canadian-based MDSI (Mobile Data Solutions Inc.) introduced the
first car-mounted terminal. The company was later bought by Motorola
who introduced the name MDT (Mobile Data Terminal).
In 1993, parts of the MDT business were separated out of Motorola again,
and were sold back to some of the original owners .
Today, the business is known as MDT Technologies Inc., or MDT for short .
- KDT/TX Terminal and Host Application Programming Guide 1
Motorola Inc. October 1988.
- Motorola MDT data protocol and interface
Including C-source for decoding bit-interleaved data stream.
Various contributors. Copyright unknown. Retrieved February 2011.
We cannot release this document as it is copyright Motorola Inc.
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© Crypto Museum. Created: Tuesday 08 May 2012. Last changed: Monday, 21 August 2023 - 20:08 CET.