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Portable communication terminal

The PX-2000 was a versatile pocket terminal, introduced around 1985 by Text Lite in Amsterdam (Netherlands), as the successor to the PX-1000. The device was intended for on-the-road word processing, calculations and communication, and allowed encrypted messages to be sent over standard telephone lines, using a built-in acoustic coupler. In The Netherlands, the PX-2000 was sold by Philips whilst in the rest of the world it was marketed under the TEXT TELL brand name.

The image on the right shows a typical PX-2000 unit with its cream coloured case, ready for use (i.e. with the lid open). The lid contains an 8 x 80 character display, which makes it far more suitable for word processing, spreadsheet and terminal applications, than its predecessor.

Apart from a word processor, a calculator, and a spreadsheet, the PX-2000 has full data and text encryption facilities built into its software. Furthermore, it contains terminal emulations for DEC VT52, VT100, TTY, VIDEOTEXT and others, allowing it to be used with a variety of services.
PX-2000 courtesy Cees Jansen [1]

A full-duplex modem is available through the acoustic coupler at the rear of the PX-2000. The coupler can be detached from the device, so that it can be used easily with any telephone handset (see below). The modem sends data at 300, 600 or 1200 baud, whilst receiving simultaneously at 75 baud. The latter is used for the VIDEOTEXT terminal emulation mode. The data format is 8N1.

The PX-2000 and its firmware was fully developed by Text Lite BV in Amsterdam (Netherlands), but was manufactured by Seiko (EPSON) in Japan. It is backward compatible with the older PX-1000, for which it supports simplex communication at 300, 600 or 1200 baud, using the 7E2 2 data format. This mode is called PX-1000 text mode [B]. When communicating with another device, the PX-2000 will detect the required protocol from the header of the first data packet.

  1. 8N1 = 8 data bits, no parity and 1 stop bit.
  2. 7E2 = 7 databits, even parity and 2 stop bits.

PX-2000 packaging
Inside the packaging
The PX-2000 in its storage wallet
Taking the PX-2000 out of its wallet
PX-2000 open
Close-up of the keyboard of the PX-2000
Reverse side of the PX-2000
Taking the acoustic coupler out
The PX-2000 measures approx. 25.5 x 11 x 3.5 cm and is housed in a cream plastic enclosure that consists of two halves: the actual computer with its 55 button keyboard, and a hinged top lid that contains an 80 character x 8 lines, single colour LCD screen. A separate yellow SEND button is located to the left of the top lid, so that can be accessed even when the top lid is closed.

The keyboard can be accessed by opening the top lid. The unit is switched ON by setting the ON/OFF switch (at the right side) to the ON position and pressing the yellow ON/STOP button at the top right. The device is fully menu-driven. Special function can be accessed by using the red function key in combination with any of the normal keys. This corresponds to the functions that are printed above each key. The cursor control keys are somewhat darker than the other ones.

Different versions
As there were many different telephone (data) standards and requirements at the time, Text Lite manufactured two variants of the PX-2000, each of which was tailored for a particular country or communication standard. At present, the following variants are known:

  • PX-2000, version 1
    This version is compatible with CCITT V23 and BELL 202 standards. It supports both C-Mail and VIDEOTEXT emulation (1200/75 baud).

  • PX-2000, version 2
    This version is compatible with CCITT V21 and V22 standard, as well as BELL 103 and BELL 212 standards. This version can not send and receive messages from the Text Lite C-Mail system, which requires the V23 standard (version 1). Furthermore, VIDEOTEXT terminal emulation is not available in this version (as it also requires the V23 standard).
The PX-2000 contains a flexible modem with an external acoustic coupler. The modem can be used in simplex, half-duplex or full duplex mode. In full-duplex mode it can only be used as a VIDEOTEXT terminal, which was common in those days. It allowed outgoing data to be sent at 75 baud, whilst receiving at 1200 baud. In The Netherlands, VIDEOTEXT was known as VIDITEL.

The acoustic coupler can be detached from the rear of the terminal, and stays connected via a short cable with a 3mm jack connector. It has a microphone and speaker, that are separated by two telescopic arms which can be extended to match the size of the telephone's handset.

Furthermore, the microphone and the speaker are spring-loaded so that they will automatically be positioned at the correct angle for the hand­set in use. Coupler and handset are usually kept together by means of the supplied rubber clip. If it is missing, a rubber band can be used instead.
Acoustic coupler attached to the handset

Reverse side of the PX-2000
Unlocking the acoustic coupler
Taking the acoustic coupler out
The acoustic coupler separated from thePX-2000
PX-2000 and acoustic coupler
Acoustic coupler attached to the handset
Serial port and audio connector
Serial port and audio connector
Serial port
The PX-2000 has a fully implemented asynchronous RS232-compatible serial port, which is available at the right side in the form of a mini-DIN connector. It allows speeds of 75, 150, 300, 600, 1200, 2400, 9600, 19200 and 38400 baud, offering hardware handshaking (RTS/CTS) and software handshaking (XON/XOFF). Baud rate, handshaking and data format are all under control of the user, and a split baudrate (75/1200) is available for VIDEOTEXT. The pinout is given below.

Memory card
Each PX-2000 terminal has an exchangeable memory module that can be accessed from the bottom side. After unlocking it, it can be shifted sideways and removed. A row of gold-plated slide contacts, mate with the contacts at the terminal's base. External memory cards with a capacity of 8KB, 16KB or 24KB were available.

The card contains static RAM, which is retained by a small backup battery on the card itself. Replacing the battery is possible whilst the card is inserted into the terminal and the terminal is powered by its batteries or other power source.
Memory card

The images below show the interior of the 8KB static RAM memory card. The PCB can hold up to three 8KB meory chips, allowing 8KB, 16KB and 24KB variants to be made using the same PCB. The backup battery is in the top left corner and is accessible through a lid in the enclosure.

Removing the memory card
Memory card
PX-2000 and memory card
Close-up of the memory card, showing a small compartment for the backup battery.
RAM Memory module (8K or 24K)
Disassembled 8K RAM module
8K RAM module PCB
8K RAM module PCB
Master reset
If the device is not responding, despite the fact that the batteries are fully loaded, it might be necessary to issue a Master Reset. This is done by holding down both shift keys and then briefly pressing the ON/STOP key. The device should then show the current firmware version number.

  • 8 lines x 80 characters variable contrast LCD
  • Exchangeable 8K, 16K or 24K static RAM memory module
  • Simplex, half-duplex or full-duplex modem
  • Detachable acoustic coupler
  • RS232 compatible serial communications port
  • Real-time clock with alarm
  • Fully secure data encryption/decryption system
  • Built-in word processor
  • Spreadsheet and calculator facilities
  • Rechargeable battery pack
Terminal emulations
  • DEC VT-52
  • VT-100
  • TTY
Supported services
  • Viditel (videotext)
  • DataNet-1
  • Telenet
  • Telecom Gold
  • Prestel (videotext)
  • Transpac
  • PSS
  • Dialcom
  • Memocom
  • Datex-P
  • Telepac
Telephone standards
  • CCITT V21
  • CCITT V22
  • CCITT V23
  • BELL 202
  • BELL 103
  • BELL 212
The PX-2000 is capable of sending and receiving serial (RS232) data at speeds up to 1200 baud full-duplex. At the right hand side is the serial socket (i.e. the frontmost socket) that can be used for connecting a computer, an external modem, a printer, etc. The 6-pin mini-DIN socket, holds data-in and data-out signals and ground (GND), plus hardware handshake lines (RTS and CTS). A 12V DC output is available for powering an external device or interface. Pin-out is as follows:

Serial port (looking into the socket)

The power (charge) socket of the PX-2000 is located at the left side, just below the SEND button. It accepts a small power plug, which a DC voltage of 12V for powering the unit and/or charging the internal 6V battery. Please note that the +12V should be connected to the ring.

Power connector (+12V at ring, GND at center pin)

The PX-2000 also has an AUDIO input and output, which are available on a 3.5 mm jack stereo socket, loated at the right side of the unit. It can be used for connecting a tape recorder and allows data to be stored on an audio tape recorder and load it back later.

Audio input and output (3.5 mm jack)

Opening the case of a PX-2000 is rather difficult. First of all, four small screws have to be removed from the bottom, two of which are located under the acoustic coupler. Once these screws have been removed, the top and bottom case shells can be separated, but four internal plastic clips at the front will keep the two halfs together. Use a small sharp object, such as a screwdriver, to find the clips and wiggle it in between the case halves, in order to unlock the clip.

The plastic clips are likely to break off as the plastic will have become brittle over the years. This should not be a problem however, and does not hamper the PX-2000's operation in any way.

The device contains one large PCB with just five Integrated Circuit (ICs) on it. At the top left is the versatile Hitachi HD6303X micro-controller with an 27C256 EPROM to its left. This 32KB EPROM contains the firmware of the unit. At the bottom center is a Fujitsu MB62H168 CMOS Gate Array, which contains 900 logic gates. Just above the gate array is a RICOH RP5C15 real time clock.
PX-2000 interior

At the top center is a flex strip that connects the PCB to the LCD screen. To the right of the flex strip is a Texas Instruments TXC3105 of which no datasheet has been found yet. It is probably a power supervisor. The big black rectangular block at the top right, marked PX-2000, is a custom-designed circuit block containing the modem, much like the custom module in the PX-1000.

PX-2000 interior
Flex wiring from the PCB to the acoustic coupler socket
Processor and EPROM
Gate array
Modifications to the PCB
More modifications
Custom-designed circuit block
PX-2000 main PCB
Firmware versions
  • COPYRIGHT 1985 WEST-TEC PX2000 Version E
  • COPYRIGHT 1987 WEST-TEC Version G 29
  1. Text Lite BV, Text Lite PX 2000 Pocket Terminal
    Full-colour leaflet (English), 2 pages.

  2. Philips Usfa BV, Text Lite PX-2000 Communication Terminal, Instruction Manual
    User Manual (English), 84 pages, A5 size, B/W.

  3. PX-2000 Warranty Card
    Orignal Warry Card (blank).

  4. Hitachi Semiconductor, HD6303X datasheet
    Date unknown. Retrieved February 2014.

  5. Fujitsu Component Ltd., MB62Hxxx datasheet
    Date unknown. Retrieved February 2014.

  6. RICOH Company Ltd., RP5C15 datasheet
    June 1995. Retrieved February 2014.
  1. Cees Jansen (former cryptographer at Philips Usfa/Crypto)
    Interview at Crypto Museum, August 2011.

  2. Hugo Krop, Personal correspondence and interview
    Crypto Museum, 25 August 2013, 15 December 2013.
Further information
PX-2000 seen from the front
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Crypto Museum. Created: Saturday 23 April 2011. Last changed: Wednesday, 24 August 2022 - 20:14 CET.
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