[Engineering Feature]
Powerful Portables
Mobile computers have come a long way over the past 25 years. But designers shouldn't sacrifice PC functionality for the latest bells and whistles.
Ruggedization is another crucial factor in the portable market. Portable devices are more prone to damage than their fixed counterparts. Combine that with the tighter hardware integration in mobile devices, and you get a significant rise in repair costs. It also impacts availablility. A unit in the shop is useless unless it's replaced.
As a result, we've seen the arrival of a wide range of rugged systems (see "Rugged Computing," p. 44). These include conventional laptops and handheld devices. However, there's a larger number of application-specific devices as well.
Two Technologies Jett*eye integrates digital photography and a barcode reader with a 624-MHz Intel PXA270 Xscale processor running Windows CE (Fig. 3). The 320-by-240 touchscreen display is readable in sunlight. It also has wireless connectivity capabilities.
TINY EXPANSION Smaller and lighter components help portable units continue their slow, downward spiral in terms of size. Nonetheless, external expansion has limited the size of these devices.
Handtop devices often used laptop connections based on large, standard PC connections. New, smaller form-factor connectors and sockets are bringing about an even smaller and lighter crop of devices.
A key player in the connection reduction is USB, due to the fact that it can use an external expansion hub. USB 2.0's 480-Mbit/s bandwidth also is critical to its success. USB Onthe-Go (OTG) permits a single connection to be used as a host or device interface. The mini-USB connectors help minimize the size of the system. Even cell phones feature USB.
USB connectors provide power, too. As a result, they can charge a portable device's battery if it's designed to take advantage of this approach. Apple's iPod is just one example.
New technology like Newnham Research's USB-NIVO may help to eliminate the need for a docking station or video output connector (see "USB Branches Out," May 25, p. 36, ED Online 12508). The USB-NIVO is a USB-attached VGA adapter. Its video driver looks like any other video interface to the operating system of a portable device. The difference is that the frame buffer for the driver isn't used to drive the display directly.
Instead, video information is sent over the USB connection to the external USB-NIVO, which has a hardware frame buffer that drives the display connected to the external adapter. The communication between the driver and the adapter is compressedand the data addresses only changes to the screen, further reducing USB bandwidth. This leaves plenty of bandwidth for other USB devices or even an additional USB-NIVO device.
Other expansion mechanisms are also changing. Very small devices have moved from the CompactFlash form factor to the SD card format. Scanners, network adapters, and wireless adapters are just a few of the devices in this smaller form factor. PCMCIA (Personal Computer Memory Card International Association) cards—the mainstay for laptops—are much larger. Their replacement, ExpressCard, also is under the PCMCIA's purview. ExpressCard is smaller, faster, and more flexible than the original PCMCIA cards. ExpressCards incorporate a USB 2.0 interface and/or an x1 PCI Express link.
ExpressCard is still much too large for smart phones, but it may find a home in handtop devices. It has additional advantages over PCMCIA when it comes to the connector. PCMCIA's socket and support circuitry were large and expensive. ExpressCard's overhead is only its smaller socket since USB and probably PCI
Express hardware support will already be standard part of a portable device. ExpressCard products are just startingto flood the market. Novatel's broadbandwireless adapters address wireless services such as EV-DO, EV-DO Rev. 1, and HSDPA (Fig. 4). As with many of the latest Express-Card devices, they use the USB connection. These expansion cards extend outside the device because of an extended antenna necessary for high-performance connections.
Wireless expansion, especially via Bluetooth, is an even more compact alternative to wired connections like USB and ExpressCard. Some of the most common uses are to provide access to large keyboards and mice, allowing for easier data entry and editing compared to tiny, built-in keyboards.
Portable computing power and functionality continue to improve while moving into even smaller form factors. Significant tradeoffs remain simply due to their small size. But their features will steadily pull more people away from laptops.
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