Original equipment manufacturers (OEMs) have a variety of hardware options when building Palm-size PCs. The following illustration shows the different hardware components of a Palm-size PC.
The touch screen is an LCD covered by a resistive touch panel. The LCD has a portrait orientation with a 240 x 320 pixel resolution. This size and resolution lets a user see interface elements clearly. The dot pitch for a Palm-size PC is either .24 or .26, depending on the OEM. The resistive touch panel enables the touch screen to work like a mouse on a desktop computer. Tapping the touch screen sends the same kind of messages that clicking with the left mouse button does on a desktop computer. The user can also select and drag items. In order to sense quick changes in user input, the touch screen has a refresh rate of at least 100 samples per second. Because a user employs a stylus or a finger to tap the touch screen instead of a mouse, cursor support is limited to a spinning hourglass for wait signals. Finally, a Palm-size PC supports 2-bit grayscale. To enhance memory, lower cost, and increase battery life, Microsoft has not included color.
The Palm-sized PC does not have a standard, physical keyboard. Text input is accomplished using the input panel and the stylus. The input panel is a standard window on the touch screen that displays an input method (IM). An IM allows users to enter data in a variety of ways. The Palm-size PC software includes a simplified QWERTY keyboard IM and a handwriting recognition IM. The stylus is a pointer for accessing a touch screen and IMs. The stylus has a smaller point than a user’s finger, yet will not scratch the touch screen.
You, the OEM, or a user can add additional IMs. For example, an independent software vendor (ISV) could create an IM for tapping in Morse code. The user can purchase the Morse code input method and install it at home. For more information about the input panel and input methods, see Palm-size PC Controls.
A Palm-size PC comes with several navigation controls. These controls can be pressed, held down, double-clicked, or pressed in combination with other controls. The following table shows the default Palm-size PC navigation controls.
Navigation control |
Description |
| On/off | Turns a Palm-size PC on and off |
| Exit | Acts as the ESC key |
| Action | Acts as the ENTER key |
| Record | Activates Voice Recorder application |
| Application | Launches an application |
| Up | Acts as an UP ARROW key |
| Down | Acts as a DOWN ARROW key |
Some OEMs may add a silkscreen region, which is an extension of the resistive touch panel, to cover a non-LCD region of a Palm-size PC case. This region is usually directly below the LCD. It is called a silkscreen region because it often has buttons painted on using a silkscreen process. While a silkscreen button is technically a software control, Palm-size PC software does not distinguish between a silkscreen button and other navigation controls; both types of buttons send the same virtual key messages. The OEM is responsible for the driver that handles the silkscreen region.
For more information about navigation controls, see Palm-size PC Controls.
A Palm-size PC includes a built-in microphone. This microphone is usually located on the front of the device to allow a user to view the screen while recording. The hardware supports 16-bit sampling at 8 kHz, while codec, the compression and decompression software, compresses the recording to 2.4 Kbps. The codec software is identical to a desktop computer’s audio compression manager (ACM). Some OEMs may add in a microphone jack for an external microphone. The jack is transparent to the software . For more information about audio input, see Palm-size PC Controls.
You can use the built-in speakers to play sounds associated with notification events. You can also use the speakers to play voice recordings or other .wav files. In addition, you can use the speakers like a pager for notification or for dual tone multifrequency (DTMF) dialing output. Some OEMs may add in a headphone jack for headphones, external speakers, or other audio-out hardware. This jack is transparent to the software. For more information about audio output, see Palm-size PC Controls.
A Palm-size PC has several notification options that an OEM may provide: audio, a flashing LED, or vibration controls, such as those available on cellular telephones and pagers. While all three of these methods are supported by a Palm-size PC, all but audio notification are OEM options.
Because a Palm-size PC is portable, battery life is very important. A Palm-size PC can run at least 15 hours on its standard battery source. A Palm-size PC also has a backup battery to avoid data loss when changing the primary battery.
A Palm-size PC supports two CPUs: MIPS and SH3. A MIPS processor has a lower code density than a comparable SH3 processor. Consequently, an application running on a MIPS CPU is larger than the same application running on a SH3 CPU. A MIPS-based Palm-size PC usually has more ROM than a comparable SH3-based device, but the MIPS-based device uses more of it for running comparable applications.
All Palm-size PC devices come with at least 6 MB of ROM and 2 MB of RAM. However, additional ROM and RAM requirements vary based on the CPU used, the components that the OEM includes with the device, and the number of components compressed in ROM.
Because it is important to conserve memory on a Palm-size PC, many Palm-size PC operating system (OS) components are compressed in ROM. When a user needs a component, the operating system decompresses that component and transfers it to RAM. Because of this transfer, compressed files slow performance. This affect is usually more pronounced on MIPS processors.
For more information about memory management and writing memory-efficient applications, see Managing Memory.
A Palm-size PC comes with a built-in serial port. Applications use the serial port for communications between a Palm-size PC and other hardware devices. A Palm-size PC can connect to a desktop computer using a serial cable or optional docking cradle that is connected to the desktop computer. The cradle is available from many Palm-size PC manufacturers. Some Palm-size PCs support data communications through a modem connected to the cradle.
A Palm-size PC includes a serial port that conforms to Infrared Data Association (IrDA) specifications. Palm-size PC devices can communicate with other Palm-size PC devices, desktop computers, or other Window CE devices. For more information about programming an IrDA port, see Using the Built-In Infrared Serial Port on a Palm-size PC.