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1980s Computers Explanation of terms

Organiser (1 and II)

Psion Organiser Model 1


Psion (UK)


Organiser Model 1

Date Launched

Mid 1984



Microprocessor type

Hitachi HD6301X @ 0.9216 MHz

ROM size

4 kilobytes

Standard RAM

2 kilobytes of normal RAM, plus 8 kilobytes of EPROM on a plug in cartridge, which held 10900 characters of data (presumably only 6 bits were used per character, and packed into bytes, ie 8*1024*8/6=10922).

Maximum RAM

Maximum of 32 kilobytes of EPROM using two 16 KB 'data packs'.

Keyboard type

Small keys similar to a pocket calculator.
There were 36 keys and they were arranged in alphabetical order rather than QWERTY.

Supplied language

POPL (Psion Organiser Programming Language) which was similar to BASIC.
POPL was only available if one of the Maths, Science or Finance application packs (costing around £40) were plugged in.

Text resolution

One line of 16 characters, 6.4mm high, on liquid crystal display.

Graphics resolution

No graphics

Colours available


Example Screenshot

Psion 1 display
This (simulated) Psion 1 display shows the limitations of the one-line screen.



Cassette load speed

No tape interface

Dimensions (mm)
Weight (grams)

142 x 78 x 29

Special features

Built-in clock and calendar (but there was no alarm function).
Included a simple flat-file database which could be searched by any word.
Built-in scientific calculator (when the Utils or Science Pak was inserted) allowed you to go back and edit previous calculations and also store them into the database.

Good points

Very robust construction with a slide-off protective case.
A 9 volt PP3 battery gave several months of typical use. (Power consumption was 40mW when switched on, 0.2mW to retain memory contents when off.)
Memory was retained on the EPROM Paks when changing the battery, for typically 50 years according to the manual.

Bad points

There was no way to entirely delete entries from the database. They could be marked as erased but still took up space in the (small) memory. This was because the storage used Erasable Programmable Read Only Memory which could only be cleared by removing the memory pack from the Psion and exposing it to bright ultraviolet light through the window on the top in the optional Psion Formatter. This cleared all data on the pack.

How successful?

The model 1 organiser was a reasonable success but the improved model II, with a larger display and more memory, sold about half a million units over a period of ten years.


The Psion Organiser (especially the Model II) was the world's first practical Personal Digital Assistant at a time when the Filofax was still a novel idea.

The Organiser had two sockets on the reverse to take memory cartridges (known as 'Paks'). Typically one was used for storing user data and the other held additional software, from Psion or third parties.

Organiser Model II LZThe Organiser II (right, LZ version), released in 1986, extended the display to two lines then to four, and had an improved keyboard, whilst retaining the same basic design. Internal memory was uprated in stages to 96 kilobytes and the capacity of memory cartridges was increased to 128 kilobytes. Eventually 'flash' memory became available, which could be deleted in the Psion rather than needing an ultraviolet eraser.

Psion WorkaboutThe ruggedness of Psion's Organisers appealed to industry and later a version called the Workabout (left) was made, with more keys and designed to be easily hand held, for applications such as stock control.

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