Electronic Design

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.

If there was a motto for mobile computing, it most likely would say "take it with you." Even before Adam Osborne started Osborne Computer in 1981, computer users have wanted to carry the power of the mainframe, the mini, and then the micro along with them (see the timeline). A great deal has changed in 25 years. Two grand will snare you lots more compute power, all within the palm of your hand. Also, you needn't look for a phone for a 300-baud modem. Multimegabit cellular links provide real-time connectivity.

In this timeframe, luggables ceded to laptops, which have bottomed out at around 2 lb. Along the way, Palm moved handheld devices to the forefront while companies such as Microsoft pushed larger tablets. All of these devices have two things in common: portablity and communication.

Also, during this chronology of minimization, we've seen batteries improve incrementally, not in the massive doses like most everything else in this domain. Take low-power processors and flash memory, which let systems run for days or weeks. And 1-in. hard disks are making more than MP3 players go around.

Remarkable changes continue to enhance the communications side, with increases in bandwidth and range. In fact, some mobile devices come equipped with more than one commmunications system.

On another front, digital cameras mark an interesting addition to mobile computing platforms. Their cost can be virtually insignificant compared to the rest of the system, and they're popping up in everything from cell phones to tablet PCs.

Let's take a look at some of the latest movers and shakers in the mobile-computing world.

Keyboards are great for text entry, but they tend to take up space for many applications. That's why the pen can be mightier than the keyboard.

Back in 1995, Zenith's 3.2-lb CruisePad tied together an 8.5-in. backlit monochrome LCD screen with a wireless local-area network (LAN). Its compute capability was limited to servicing the network, driving the screen, and handling the stylus.

In 2001, Microsoft introduced the Tablet PC. It was bigger and heavier than the CruisePad, but it was a true mobile-computing device. Touted as a revolutionary change, the Tablet PC, like many of its cousins, never replaced the laptop.

Some convertable laptops take on the guise of tablets, but that keyboard remains an important feature for people that need a PC. Still, tablet PCs have found a number of significant niche markets.

Grayhill is one of the vendors targeting the custom mobile-computing markets for applications like public safety, fire protection, construction, transportation, and the military. Its mobile series are built around an XScale processor running Windows CE.

Customers select features such as form factor, screen size and resolution, keypad functionality, wireless support, GPS support, connectors, and peripherals. The final design often is a ruggedized system because it's designed to be deployed in the field. Custom application software support typically is part of the package.

Custom solutions usually are cost-effective in quantities as small as 100 units.

Nonstandard peripherals such as bar-code and RFID scanners often are included.

Palm made the palmtop/PDA (personal digital assistant) market with its Palm Pilot. Research in Motion's BlackBerry untied handheld with wireless connectivity. Palm's Treo opened the smart-phone market.

Companies are building corporate communication infrastructures around devices like the Treo. One such company is Medtronic, a leading medical technology company (see "Mobile Medronic," p. 42).

The Treo 700w is the latest version of Palm's smart-phone offering (Fig. 1). It sports a 312-MHz XScale processor that runs Windows Mobile 5.2.2 Pocket PC Edition, a version of Windows CE. It also has 128 Mbytes of flash, a 240- by 240-pixel display, and a full QWERTY keyboard.

Wireless support includes digital cellphone suport, Bluetooth, and cdma2000 EvDO. The unit also can double as an MP3 player and a 1.3-Mpixel digital camera.-The expansion slot supports MultiMediaCard (MMC), Secure Digital (SD), or SDI cards.

Operating systems (e.g., Windows CE) that target mobile devices often hold an edge when it comes to aspects such as reduced power consumption. But many users want the full functionality of their desktop or laptop. That's where OQO stepped in with its 4.9- by 3.4-in. Model 1+, which comes with built-in Bluetooth and 802.11b (Fig. 2).

The Model 1+ uses a novel sliding display that reveals a small keyboard. Keyboards tend to be a key ingredient for operating systems such as Linux and Windows XP because most applications are written with a keyboard in mind. Soft keyboards and pen-based character recognition are usually the second choice for most users.

Baochi Nguyen, OQO's senior enterprise marketing manager,had some interesting observations from OQO users. First, Web-based applications worked very well with the smaller screen because Web pages resize themselves, while Windows applications are usually designed for the 1024-by-768 resolution typically found on a desktop PC. This can affect corporate decisions on whether applications need to be modified to be used effectively on a smaller system. Second, the 14-oz Model 1+ is used more often with its keyboard.

This 1-lb "handtop" space has come and gone a number of times. The Poqet didn't last because of its high cost and low performance compared to full-size or compact laptops. However,-the FlipStart arrived to fill the void. It's even smaller than the Poqet, and it can run Windows XP. It has a 30-Gbyte hard disk, a 1-GHz processor, and 802.11b/g WiFi support—all specs similar to the OQO Model 1+. The FlipStart also adds a 1.3-Mpixel digital camera.

This category, minus the keyboard, has been popular for games and the latest crop of personal video platforms. In fact, Microsoft's Ultra-mobile PC (UMPC) attempts to formalize it. From Microsoft's perspecitive, applications such as car navigation systems, digital TV tuners, and even Web cameras can benefit from UMPC. Unlike earlier Windows CE-based solutions, UMPC runs the pen-supported version of Windows XP.

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.

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.


Good Technology
Newnham Research
Research in Motion
Rugged Notebooks
Two Technologies

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