Tandata P.A.

The Tandata P.A. Story

Tandata Marketing Ltd. were known for creating Prestel Video Terminals and Modems. By 1984, they were luring in engineers from the declining sister company Tangerine Computer Systems with the opportunity to create a brand new microcomputer - codenamed Minerva.

Minerva was a machine for professional users with a focus on personal management and productivity. The machine was in development for three years and released in early 1986 as the Tandata P.A. - and Personal Assistant was very apt.You could log onto Prestel and view your stocks, manage your bank account and check the news. You could pick up your telephone and have the machine dial any of your stored contacts. Manage your finances with the spreadsheet in ROM, and connect to your work mini computer via terminal. The machine is highly integrated and user friendly, you are not directly exposed to the underlying Unix Operating System.

This machine was set to revolutionise the office, and had another big advantage. Using the internal battery, the savvy user could take notes and keep accounts while on the move using the 20*2 column LCD screen, then plug in at the office to recharge and go again. This machine did not even have a power switch - the machine boots when the LCD screen module is tilted up, otherwise the machine is left in a low power sleep mode. The P.A. is a lightweight, truly portable computer, and is an overlooked early entry into the PDA and mobile category of machines.

There were plans for multiple P.A.s - the Tandata P.A. 100, and a more expensive multi-user Tandata P.A. 200. It is not clear if the 200 was ever built or released. The machine did not ship with the promised built in speakerphone present in early review units because getting approval from BT was so difficult. It had instead a telephone line passthrough which enabled you to use your computer with your external handset. Other telephone integrated machines were already on the market such as the Acorn Communicator, ICL One Per Desk and STC Executel.

In 1986, the machine went on sale with a
13" colour monitor and 64k RAM for £995

Early reviews and sales for the P.A. looked promising, but disaster struck after only a few months of machines being out in the wild. Tandata made the bold choice to keep its file system in battery-backed volatile RAM. This meant the machine would be incredibly convenient and responsive, however if you ever lost power to your RAM or had a fatal error requiring a cold reboot, all stored data would be lost. Unfortunately for Tandata, many of the machines were coming back with this problem, and the lack of a real power switch meant crashed machines were unrecoverable without a technician.

The main PCB was mounted in the case upside down, dangling the RAM and ROM chips in thier sockets. This is not usually a problem, but combined with the portability, ROM and or RAM chips could potentially get dislodged when the machine was moved about and placed down heavily. Remarkably, the watchdog of this machine was clever enough to detect this error state and display a message.

The following was found etched in Rom, and serves as its epitaph:

Resetting machine, All data Lost.
Very, very Sorry

This error was sporadic and hard to debug, taking months to identify the issue and replace the inadequate ROM sockets, but by the time this was fixed the perception and momentum of the machine had suffered. After two production runs the machine was discontinued. AB Microelectronics, the company that built the machine, bought the rights to the computer alongside most of Tandatas assets in 1989.

The P.A. ceased production in 1989.
It is not publicly known how many were sold.

The Tandata P.A. is an advanced relic of an alternative future. Its a bold, innovative online computer betting on a forerunner of the web. It was ahead of its time and had stalled before it could fulfil its own vision of computing in the following decade. Its for these reasons and many more that this machine is very special and we salute all those who worked on her.

Read more at BinaryDinosaurs.co.uk

Machine Technical Specs

  • CPU: NEC V20, 4.7Mhz 8088 compatible chip.
  • Graphics: EF9345P 8bit, RF + RGB
  • 16 bit CPU, 8 bit Bus
  • Built-in 2 Column LCD display*
  • Built-in v21/v23 modem and auto-dialer.
  • Battery Backup*
  • Tandata 13 inch monitor
  • Parallel Centronics Printer Port
Input / Output
  • UK Telephone in / out
  • RGB (Scart) 8 Pin Din
  • Tape / Video 7 Pin Din
  • Power 4 Pin Din
  • TV RF Output
  • IO Expansion 20 Pin Header
  • RS232 DB-25
  • Centronics Printer 20 Pin Header
  • External Modem 16 Pin Header
  • Phone Book
  • Notebook
  • Data Communications
  • Calendar
  • Spread Sheet
  • Calculator
  • Electronic Mail
  • Files
  • System Management
Screen Modes
  • TTY
  • Prestel
  • Prestel IP
  • P.A.
  • VT100
  • 3270
  • Teletext / Travel*
  • NCR 7900
Modem Modes
  • 300/300 (V21)
  • 1200/75 (V23)
  • 1200 H-D (V23)
  • 4800 H-D (external only)
  • 4800/75 (external only)
  • 300/300 (BELL 103)
Modem Support
  • Internal modem (VT-100)
  • External modem
  • RS-232C port modem

* The particular machine in this collection is an unusual screen-less version of the P.A. It is a cost-reduced model made for Hogg Robinson Travel Agents. The portable features were removed, so no included battery or 2 column LCD screen. The keyboard layout is slightly altered, and it contains a unique ROM set which includes a special mode for use by the Travel Agents internally to make bookings and enquiries.

Tandata P.A. Software

The P.A. video user interface is snappy and minimal. Navigation is done using the number keys to access options as displayed on screen, and a press of the Menu key at the top right of the alpha section of the keyboard takes you back up the menu heirarchy. Solid state storage makes this machine very capable. No loading times until you need to connect to the outside world, which it could do by various modes.

If you power on the machine when the RAM is unpowered the machine enters a boot routine which partitions the ram into a file system and rebuilds the entire operating system while self testing along the way. This only takes a few seconds and is called a "Non-volatile machine status reset". At this point you have a factory reset machine.

You are initially prompted to "Please Enter Identity:" - where multiple login accounts could be set up and used. To log out you select "Finish Using P.A." from the Main Menu.

This machine uses the familiar Prestel / Teletext style that is instantly familiar to many people of a certain age.

Ver: PA %-3d1.3B/%02x-HRT 13
Created on :-
Not for General Release.

Tandata P.A Teardown

When I first got hold of this machine several years ago it was clear it had been used heavily in a prior life.

Scrubbed up nicely. The key legend has discoloured but it still looks great.

Tested on 14th December 1988. Not sure if this is pre sale or post return. The cover here is a useful ROM access hatch.

Overview of the PCB. Access from bottom side. Nice compact layout but lots of bodges. Good condition.

ROMs are labelled HRT13 Z50-Z56. The PIA board is visible above the roms. Roms binaries have been extracted. HRT refers to Hogg Robinson Travel.

PIA removed. Connected via dual header and separate power wire.

The PIA board contains a reference to the project codename. Minerva NMOS Emulator Issue 8.

The graphics chip is extended onto a daughter board with some mysterious scrubbed out chips.

Close up of the extended video card.

Underside of video card.

Empty video dip socket.

The keyboard disconnects via flat flex type connectors but the speaker wire is soldered down.

Underside of PCB

A small foam cube takes the place of the battery. The keyboard is membrane but very solid.

The keyboard insulators are cut outs of the front panel of the Tantel by Tangerine

This is part of the Tantel terminal (1981) keypad.

The keyboard is not a Cherry MX like the sister machine Tandata TD4000.
Key caps are dual shot injection molded. Shift, Return and Space have stabilising bars.

Sitting in front of a TD1000/4 box

The other PA units switch on by tilting the LCD screen up. This one has a simple ON switch. The blanking and retention plates over the phone jacks is a nice touch.

Need to figure out the pinout of the power connector.

The battery compartment has a working connector inside but has no battery. The foam packer suggests its never had a battery in it.

If you have any more information about Tandata or this machine, please get in touch.

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Tandata P.A.