An electronic device that fits in your pocket* and helps you to organise your hectic life. Usually features a calendar, clock, notepad, and calculator/currency converter in software form- even in modern devices quite a lot of the day-to-day functionality is built into the hardware. PDA's have developed from glorified calculators to fairly mature portable computer platforms in their own right, aided by advances in storage and battery technology as well as I/O functions that greatly extend their usefulness (such as linking to the net, and to digital cameras, Bluetooth-enabled printers and other devices). But I'm not here to give you a reference book definition, I want to argue my case that Palm, Psion, Handspring, Compaq, Sony and the rest are barking up the wrong tree when it comes to PDA design.

*Measured in marketing terms, i.e. ranging from the size of a packet of cigarettes to slightly larger than the boot of a car.

The PDA I want*

Whenever I browse through the Personal Digital Assistant section of a shop or catalogue, the first thing that strikes me is that these devices are being tailor-made for a consumer that probably doesn't exist, at least not in large enough numbers to make any one of the major players progress from being a luxury toy to a ubiquitous portable computing platform. Either they are shackled to a proscribed set of tasks, or they present heavily pruned versions of a larger machine, where the pruning has had the inevitable effect of rendering the machine next to useless.

Palm and its derivatives seem obsessed with handling tasks that can already be simply and conveniently performed on paper, or with a calculator or similar far less complex dedicated device. Microsoft's heavily-marketed Pocket PC efforts try to shrink down the desktop experience (by which they mean Microsoft Office) into an unsuited and ergonomically hostile form. Psion's machines are cool, but too big considering there are subnotebooks slightly bigger and far more powerful. Needless to say, all sides' offerings are overpriced, underpowered and overambitious.

Rather than go on listing a catalogue of gripes about the existing (patently embryonic) devices on the market, I think that it would be easier to illustrate my point of view by designing a conjectural 'Ideal PDA' of my own. This thought experiment will be constricted by the technology currently available, albeit not entirely rigidly, as the march of miniaturisation will doubtless allow some of the more optimistic elements to be realised within a short space of time.


Physical dimensions: 120mm x 50mm x 8mm (possibly much smaller)
Casing: hard matte-finished plastic (or other rigid durable material)
Power: proprietary rechargeable cell, about 1/3 the length of a mobile phone battery, 4mm thick

The casing does not have rounded corners or edges. All the surfaces are completely flat (bar I/O jacks). Note that the machine is narrower than an AA battery. AA batteries blow.


dimensions: 90mm x 40mm
resolution: 320x160 or thereabouts.

The screen is a reflective TFT, of the same type as that found on the NeoGeo Pocket Color, except with a larger area (and therefore higher resolution). The important factor is dot pitch: try to cram too many elements into a small area and the greater number of gaps between the elements results in a darker display (as seen in the Game Boy Advance). The screen is not lit.


Microswitched d-pad (does not protrude from the machine)
Around 6 function buttons

Held horizontally, the screen takes up 5/6ths of the width of the unit, leaving 1/5th at the far edge, where the existing devices would place their utterly pointless four function buttons. In this space there is a directional controller, and (maybe) one or more large, universal, function buttons. There are additional buttons (including a rubberised power button) on the side faces and the back of the machine, if necessary. (Possibly a replaceable outer casing would allow for different button placements and configurations).

The screen is not touch sensitive, unless there is a very cheap and robust way to make it so- and then only enough to facilitate an on-screen keyboard, operable by fingertips. My prefered solution would be to have an attachable keyboard around the same size as the machine, allowing it to be used like a Psion.


1 USB port (possibly requiring a smaller, proprietary connector/cradle on the machine's end)
Infrared link and/or Bluetooth link/wireless ethernet link

The point of the machine is that it can't do all that much itself, but can link to your GPRS-or-better phone (and thereby server-side apps) and your PC.


The device may have one flash memory socket, but more likely will have solid state memory built directly into the machine. 32 megs should be more than adequate, megalomaniacs could fit more.


The device does not necessarily need sound. If sound hardware can be practically included (e.g. integrated to the processor) then the device may have a small headphone jack. A builtin speaker, of the same type as in a digital watch, may be required for alarm clock function.


A bit of a grey area, as I don't know what the options are for such a device. Presumably it will need to fit as much of its workings as possible onto one small, cool chip. Because this is fiction, let's say it's running an embedded Linux OS and has a full loadout of dedicated software. And is x86 compatible. Or maybe has a hardware JVM. Or something, the point being it should be easy and beneficial to code for.

FIG. 1: The imaginary PDA device. 
Apologies for possible ASCII art lameness.

   /   ⊂⊃  ⊂⊃                                           /|
  .-----------------------------------------------------. |
  | .----------------------------------------.          | |
  | |                                        |    ___   | |
  | |                                        |   ' ↑ '  | |
  | |                                        |  |← o →| | |
  | |                                        |  '  ↓  / | |
  | |                                        |   '---'  | |
  | |                                        |          | |
  | |                                        |  ⊂⊃ ⊂⊃  | |
  | |                                        |  a   b   | |
  | |                                        |  ⊂⊃ ⊂⊃  | |
  | '----------------------------------------'  c   d   | /

  (possibly shown larger than actual size)

Tasks it can perform

Tasks it cannot perform

As a corollary, I will stipulate that it can be capable of connecting to the internet with no external hardware, if technology exists that allows this functionality, including transmitter-receiver and modem if required, in less than the size of a postage stamp, and for less than five pounds on the retail price. (So not now, in fact, but maybe in the next five to ten years.)

If any company can develop a device like this (and I don't see why it shouldn't be possible with current technology- it need be much less powerful than a Pocket PC for instance) and price it sensibly, I will gladly purchase one or three.

*special accusations-of-GTKY-encouraging subtitle.

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