PX1000 was a small hand-held message terminal, that was used for creating and sending text messages over standard telephone lines, using a built-in acoustic coupler. The PX-1000 was introduced in 1985 by Text Lite in Ireland and was sold by Philips (Netherlands) and others.

The standard version was a simple text terminal, that allowed messages to be entered, stored and transmitted over a standard telephone line. It had built-inDES-based encryption/decryption. It can be recognised from the red MODE-button. This version was developed in 1983.

The initial Text Tell PX-1000 was developed by Text Lite Ltd. in Ireland in the early 1980s, probably in 1983. It allowed people to create simple text messages and send them by phone anywhere in the world. It had a built-in memory that could hold up to 7400 characters. The firmware inside the PX-1000 was written by West-Tec Ltd. in Ireland, who were probably also the hardware manufacturers. 

The initial version was introduced in late 1983 or early 1984. It contained a word processor and the ability to send and receive encrypted messages. The firmware of the 1983 model was contained in ROM whereas EEPROMs were used in later versions. The initial version was followed by a model where the encryption facilities were replaced by a calculator. Most of the later version carry 1984 firmware and were probably introduced in 1985. 

In The Netherlands, Text Tell equipment was sold exclusively by Philips as a re-badged product. The packaging and the terminal itself, carried both the Text Tell logo and the Philips logo.

Technical specifications:

Firmware: COPYRIGHT TEXT LITE 1983 (ROM).
Data rate: 300, 600 or 1200 baud
Data format: 7E2 (7 data bits, even parity, 2 stop bits)
Power: 12V DC via external adapter
Display: Single line monochrome LCD
Memory: 7400 characters
Modem: simplex

Text Lite Ltd. was founded in 1979 by Derek Blennerhassett and was based in Monkstown, a suburb of Dublin (Ireland). Initially they were involved in diverse areas, such as Audio-Visual and Electronic Display Systems. The majority of these systems were sold in Ireland, but their Text Tell PX-1000 series was sold overseas as well. In later years, Text Lite (now renamed to Text Tell Ltd) developed into specialists in the areas of Labelling, Safety and Identification, selling the products of two well known companies: Brother (Japan) and Brady (USA).

Specifications:
APPENDIX I-PX AUDIO
TRANSMISSION FORMAT
1 start-bit
8 data-bits, LBS first
1 parity-bit (even)
2 stop-bits
MARK = 1300 Hz, SPACE = 1700 Hz
MARK = 1, SPACE = 0

Header:
300 baud transmission starts with a 2 second MARK, followed by:
Bloc-number, most significant byte first (in case of encrypted text, size + 32768) baud-rate of data, one byte: 
Low speed = 300
Normal = 600 (default)
Highspeed = 1200
end of header: 0,5 sec MARK
any parity-error, or any unacceptable
data will restart the reading process.
Receiver waits for 0,5 sec MARK.

Data:
text is divided into units of 8 bytes plus a vertical parity byte.
Blanks are added to the last unit whenever necessary.
Even parity is used. End of transmission:1 second MARK.
Frequencies are complying withCCITTV 23 Standard.

APPENDIX II - PX SERIAL DATA OUT FORMAT
1 start-bit 7 data-bits
1 parity-bit (even)
2 stop-bits baud rate: 1200
logic 1: -5V(plm 10%) logicO:+5V(plm10%) busy (handshake):    0,8V max. ready (handshake):     2,0V Data levels are complying with RS 232 C and V 24 Standards.

APPENDIX III The Coding / Decoding system used in the PX 1000.
Whenever a text is 'encrypted1, all characters in the PX memory are
transformed into numbers that have absolutely no discernable meaning -
except for a PX with the right KEY entered!
Important is, that the encrypted text itself contains no clues whatsoever to
find the right KEY. There are over 72.057.590.000.000.000 possible different KEYS.

At the present time, and in the foreseeable future, it is not feasible to run a program -on any computer- that tests all these KEYS for clues to what the encrypted data might represent: all possible KEYS have to be tested one by one. This tedious process will prove to be an impossible (too lengthy and costly) job. That is why this method of encryption is
chosen as an Industry Standard by the U.S. Nat. Bureau of Standards:  The
Data Encryption Standard.
The encryption algorithm used in the PX was tested according to the instructions set out in the U.S. National Bureau of Standards Special Publication 500-20, and found compatible with the Standard.

We are very grateful to http://www.cryptomuseum.com/crypto/philips/px1000/index.htm where you will find further details.

Our unit together has a model is a Text Tell PX 1000 with a serial number of 004731 40110. This is complete with the PXP 40 printer, soft cases and operating instructions and was kindly donated on behalf of Alan Christopher Craig.