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Defining The Portable Concept

Posted on December 11th, 2015 by ScienceDude

Just a couple of years ago, if you said, “mobile computing,” everyone knew what you were talking about: laptops. These densely packaged, battery-powered little PCs were popping up everywhere. But the rapid increase in processing speeds and chip densities, coupled with the advancement of display technology, has lowered the cost of computing power, sparking the development of whole new classes of computing and communications devices.

Today we have notebooks, subnotebooks, mini-notebooks, hand-held PCs, personal digital assistants, smart phones, and two-way pagers. But we don’t need to tell you that; you probably already have two or more of these little devices. And we don’t need to tell you which kind of device is good for particular kinds of computing and communications; you’ve probably got that down, too. Instead, this article looks at how these devices are going to evolve into their next stages–what technologies need to change and what kinds of devices you can expect to be able to purchase during the coming year.

Balancing Act

Designing a portable computer is one of the ultimate expressions of the phrase “engineering trade-offs”; when you change x, you must also change y. If you want a larger monitor, you’re going to add weight and power consumption. Conversely, if you want a 2-pound computer, you’re going to sacrifice things like battery life, monitor size, and keyboard size. Everything must balance.

Here are the 15 areas where most of the trade-offs happen:

1.  Case design, size, and weight 2.  Processing power 3.  Memory 4.  Keyboard
5.  Navigation devices 6.  Display 7.  Video circuitry 8.  Video input 9.
Storage 10. Communications and networking 11. Battery life 12. Heat
dissipation 13. Connectors 14. Additional I/O devices 15. Expandability

We can examine some portable-computing issues, including how these machines interact and where they might be headed, by designing what at least one BYTE editor considers an ideal portable computer, looking at what is (and isn’t) possible with today’s technology (see the text box “Proposing the Perfect Portable” on page 80NA 2).

As for what we can expect during the next few years, let’s look at it while performing a modified version of that hoary old party dance, the hokey-pokey.

You Put Your Data In

tecraGetting data into a computer is a necessary first step. Right now, for most purposes, that means a keyboard. Some of the ultra-thin systems coming out this year have keyboards with a very short throw: a millimeter or two. This makes a keyboard feel stiff. The ultra-narrow systems have narrow keyboards–in many cases, too narrow for touch-typing (witness Toshiba’s Libretto and most of the Windows CE hand-held PCs). IBM has experimented with its “butterfly” collapsing keyboard. All these examples have drawbacks, and no “savior keyboard” is on the horizon.

But speech recognition, already surprisingly effective, is developing fast, and some full-size laptops now come with built-in software. Micron, for example, bundles Dragon Systems’ Naturally Speaking with its notebooks. Speech will likely become much more widespread in the future, but it’s unlikely to replace the keyboard completely in the foreseeable near term–either on the road with portables or in our open-door, open-top office cubicles.

What about graphics-based input? Toshiba’s Tecra 750CDT laptop was the first to include a video camera for conferencing and scanning. This should also be a boon for those who do library research.

Smaller machines (i.e., PDAs) can get by with stylus-based input, either through tappable on-screen keyboard grids, like the T9 keyboard in Texas Instruments’ Avigo, or handwriting recognition, like the Graffiti alphabet in the 3Com PalmPilot. But this works simply because you don’t enter much data that way. According to several vendors, a stylus will be around for some time in small-screen devices, simply because fingers are too big and regular pens damage display screens. For serious data entry, such as getting 1000 addresses into a PDA, you download the information from your PC over a cable or IR link; there’s no practical alternative.

You Get Your Data Out

With a portable, output is normally the display screen; printing is rarely an issue. Displays represent a problem in terms of future development, for several reasons. First, today’s flat-panel LCD screens are already good enough, big enough, and bright enough for most users; they don’t need significant improvement. “The 14-inch TFT [thin-film transistor] display is actually significantly better than most 17-inch CRT monitors,” says Greg Munster, product marketing manager for Hewlett-Packard’s mobile-computer division, “and thus it’s all most users really need or want.” But the big screens don’t cut it in terms of price and power consumption. Ironically, the worst problem of all might be size. We all want a bigger screen, but we want the total package to be as small and light as possible.

How do you shrink a display screen without shrinking the image? There are three likely possibilities: a display whose physical size can be reduced for transport and enlarged for use (e.g., some kind of foldable LCD or mirror-based system), an image projector with a folding screen, or a tiny image that’s magnified by a lens. The first would be useful, but so far no one seems to have invented one. The second is really just speculation, because it raises even more severe power and brightness questions than the current technology.

But the third might soon be possible. A number of companies, including DisplayTech, Kopin, and Siliscape, are developing small LCD displays that you can hold up to your eye behind a lens (think one-eyed View-Master slides, and you get the idea) to see a decent color image.

At the present time, the resolution is at VGA levels and the number of colors is limited, but the potential is there (see “Mini Displays Get Sharper Focus,” September 1997 BYTE, page 24). Indeed, Rockwell incorporated such a display into its body-mounted computer, the Trekker (see “Wearable Pentium,” September 1996 BYTE). Kopin has demonstrated a display small enough to be built into a Motorola Startac, the smallest cellular phone on the market, so getting faxes on the run might someday be truly easy.

You Store It on Your Hard Drive

Disk drive technology is, for the moment, advancing faster than Microsoft’s attempts to occupy it all for Office 9x, so storage capacity isn’t much of a problem. IBM is currently supplying 8.4-GB hard drives in some ThinkPads, and more will come. Solid-state or other nonmagnetic technologies might eventually replace magnetic disks, but not soon. And high-capacity removable drives–those of the Zip/Sparq/Shark/SuperDisk/Jaz/Quest ilk–will take care of the need for moving data physically.

Digital versatile disc (DVD) drives are starting to appear as options on some full-size laptops. Apple’s Greg Joswiak says that “the availability of DVD will be important for our newest generation of PowerBook laptops, which are heavily used for graphics presentations and video-intensive applications.”

And You Bake It All About

Heat has been a constant concern of designers of full-function laptops and associated peripherals. The first 5-V Pentiums and older DRAM chips ran at shockingly high temperatures and required fans for cooling. Earlier hard disks were also serious heat producers, and we’ve had more than one PC Card modem that ran hot enough to fry itself. However, the modern versions of all these components run much cooler, and heat-control methods have also improved through the use of conductive fluids, heat pipes, innovative heat sinks, and, yes, fans.

Increases in clock speeds that would otherwise present a serious thermal challenge to laptops have been largely offset by accompanying decreases in physical sizes and operating voltages. The highest-speed mobile Pentium CPUs made with 0.25-micron technology today run at only 1.8 V internally, while memory and I/O run at 3.3 V. Intel’s Mobile Power Guidelines for 1999 target the core at 1.6 V, and memory and I/O at 2.5 V. According to Intel, average laptop power consumption (excluding displays) has doubled (from 10 to 20 W) from 1994 to 1997, and if heat dissipation isn’t addressed, it’s projected to nearly double again by 1999.

With proper management, however, the thermal load can be restricted to 23 to 25 W. For smaller portable devices, lower-powered, non-Intel CPUs, such as Hitachi’s S3 and Digital Equipment’s StrongArm, simplify heat-control issues.

Closely allied with heat is battery power, since excessive heat means wasted electricity. Therefore, heat reduction contributes to longer operating time between recharges, as well as increased battery longevity through reduced thermal stress.

Battery life (i.e., time of operation) has always been a point of contention, with users needing more than portables can deliver, and with manufacturers quoting highly optimistic specs. Today’s lithium-ion cells represent the third generation of laptop battery technology, and at the moment there’s no near-term replacement in sight that offers greater energy density in a compact package. (Zinc-air and starved-electrolyte cells have been shown for laptops, but they’re currently too bulky to build in and are suitable only for add-on battery packs.) For the business sky warrior, airliners with the new generation of computer-friendly power plugs are a welcome development that will take some of the pressure off laptop and battery designers alike.

You Do the Clickey Pokey

With GUI screens and most modern software usable on portables, you absolutely need to have a pointing/navigation device. Yes, you can certainly perform a lot of operations in Windows 95 or NT or the Mac OS using keyboard shortcuts, but you can’t do everything.

So, you need a (choose one): mouse, mouse-on-a-stick, touchpad, trackpoint, joystick, trackball, digitizing pad/pen, or touchscreen. The mouse was there first, and most desktop systems still have one, with trackballs coming in a very distant second place. The other pointing devices were all designed to concentrate fingertip screen navigation into a small, fixed space. They all work–some better than others–and we will likely see even more ingenious systems in the future.

And You Connect Yourself Around

One problem facing portable designers is the number of different connectors they must incorporate into their machines for communications and peripheral hookups. A typical full-size laptop these days can have almost two dozen I/O connectors and switches on the outside of its case. And there still have to be bays for removable drives and batteries, plus upgrade access to the memory and hard drive.

The universal serial bus (USB) standard, which can hook up to 127 different devices, is one good possibility for replacing many, though not all, of those varied connectors. Also, eliminating the number of different components would noticeably reduce the manufacturing cost of the system for both parts and labor.

For all its potential, however, USB has been slow to catch on, and it’s not clear when it will reach the critical mass of acceptance. There’s still only a trickle of USB peripherals available, and most of the things people want to plug into their portables need some other connector.

A pure USB machine is an interesting idea, but it seems to be science fiction. No portable maker we talked to, including Compaq, HP, and Toshiba, seems to be even considering such a machine. Mark Hanson, a product manager for Compaq’s Armada laptops, thinks the great number of legacy peripherals will limit USB’s acceptance. “IEEE-1394 will be more likely to replace some other connectors and will also be implemented in drive bays, although it raises some power-management issues,” he says. For better or worse, USB seems to be not a replacement but just one more connector standard–aggravating, not solving, the problem.

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