i dunno. 
"The Tungsten T, introduced in November 2002 and known during
development as the M550, was the test balloon for both Palm OS 5
and the entire Tungsten line. The Tungsten T was designed by Palm
engineers based in Arlington Heights, IL. It has 16 megs of memory,
a Texas Instruments OMAP (ARM) 144 MHz processor, a built-in
microphone, and runs Palm OS 5.0. It is 4.0 inches (102 mm) tall,
4.8 inches (121 mm) tall with the slider extended, by 3.0 inches
(78 mm) wide by 0.6 inches (15 mm) thick, and weighs 5.6 ounces
(146 g). It has a standard 3.5 mm headphone jack, and a single tiny
speaker. (It is otherwise a standard Tungsten; see above.) It sets
itself apart from other PDAs physically by having a sliding lower
portion; the bottom third of the casing can be slid up and down to
cover or reveal the touch-sensitive Graffiti writing area. At
introduction, it was US$499.
Many of the features in the Tungsten T are Palm firsts, in response
to Sony's successful Clie series. It was the first Palm PDA to use
a version of Palm OS 5 and an ARM processor, which meant that it
had the software and processing power for high-quality real-time
video playback and mp3 playback. It was the first Palm PDA to have
a 320 x 320 resolution screen, what is known as "hi-res" in
enthusiast circles. It was Palm's first PDA with built-in
Bluetooth. It was the first Palm PDA with a microphone, for
recording voice memos.
The slider was the real innovation and what made it a critical
success, though. When open, the Tungsten T looked like a normal
slate-shaped PDA, but the bottom portion, with the five-way
controller and four buttons, could slide closed, covering up the
Graffiti writing area. This made it much smaller for keeping in a
pocket. Palm's reasoning behind the slider was people spend more
time viewing data rather than entering data. Thus, they chose to
hide the data entry medium while not in use to make a more compact
device."
