Colour or Monochrome?

A

lthough all current PDAs (2007) have a colour screen and many users immediately discount the monochrome cousins, to dismiss an older device owing to the fact that it does not use a colour screen could be foolish depending on what the user wants and needs from their device. For some users a monochrome unit would be just as effective as a colour device, perhaps more so.

In an ideal world, of course, all of our PDAs would use a colour screen. Colour does make things easier to see, or rather, it can do so providing the software has been written to take advantage of the greater abilities. For PalmOS devices, simply running an application designed for monochrome devices on a colour device simply means that you get a monochrome application. Yes, admittedly, some applications are written to encompass colour - but the majority just default to the standard PalmOS colours (for PalmOS 3·x and 4·x, this is a mix of blues, black and white, and the odd grey thrown in too). However whilst colour is nice to have, a high resolution screen is arguably a better upgrade.

Colour screens do offer some important advantages, especially if the user’s eyesight isn’t what it used to be. Firstly, they usually offer improved contrast under most lighting conditions - but see later. Secondly, they can offer black on white text, which is initially easier on the eyes, but can get quite tiring after some time. They also offer the opportunity of colour-coding text, icons and menus.

However, it is important not to lose sight of the disadvantages, too. The first disadvantage is that for a colour screen to show off bright colours, it needs to be brightly illuminated. This in turn requires a backlight, which of course requires a much greater amount of power - and this brings other compromises elsewhere in terms of battery capacity, size and weight. Another consideration is the cost and complexity of the screen hardware - although the LCD itself may not be heavier, a 16-bit display requires much more data to be shunted through to it compared to a 4-bit display. This in turn can be to the detriment of the overall system performance, although it does very much depend on how the PDA was designed. In come cases the manufacturer provides additional display hardware and the net effect on system performance is an improvement. Witness the Palm IIIc as a sluggish colour device and the Palm m130 as a rapid colour device.

There are some new technologies being developed that will narrow the gap between colour and monochrome screens in terms of power consumption - in particular, Organic LED (OLED) screens, introduced by Sony for the CliÉ range before it was dropped. OLED offers the prospects of much reduced power consumption, a smaller footprint, a faster response and significantly reduced manufacturing costs compared with conventional LCD screens.

However, until then, most monochrome PDAs offer a battery performance advantage their colour cousins. The Palm m125, for example, offers a battery uptime of approximately thirty hours, whereas the Palm m130 offers a theoretical uptime of just ten hours.