Illustration by Kevin Short

In the final analysis, flexibility wins--whether in control systems, user interfaces, or life.

Reprinted from Windows Tech Journal, 5 (9), September 1996.

Larry Constantine is a member of the Science Fiction and Fantasy Writers of America and the author and editor of numerous works of fiction, including the critically acclaimed original anthology, Infinite Loop: Software Development's Own Anthology of Science Fiction (CMP Books, 1993).

He could see Isaac through the window, towering over the distant Sydney skyline. Time to get to work, Barry thought, scratching at the gray thickets above his eyes. He put his notebook to sleep, then stared moodily into the muddy dregs in his coffee mug. The program could wait. It wasn't a real program anyway, just an applet for the guy in the sandwich shop.

And I'm not really a programmer either. So what am I? Barry wondered. He had trained as an engineer when engineering was cool, and had become a shuttle pilot at a time when astronauts were heroes. Unfortunately, the job market for ex-astronauts was pretty limited. There were only so many brands of food concentrates or designer crash helmets needing endorsement by small-time heroes. A shuttle jockey might still rate a free round at the pub, but that didn't pay the rent. Too old to join the commercial fleets, Barry Munro had spent a couple of impecunious years in "early retirement" before taking the job in Sydney.

"I'm a tower jockey, Emma, just a tower jockey," Barry hollered toward the half-open door into his wife's office. Of course, he knew Emma didn't hear him. She never did. Barry leaned back in his chair until he could see into the other room. Emma was on the phone. He couldn't follow every word of the Ameslan she was signing, but he caught enough to know she was talking to her mother about his raise. She was always so damned proud of him.

"And it's not a promotion." He said to the door. "Some corporate schmuck just thought up a new title. 'Stabilization Engineer.' Like calling a damned janitor a maintenance engineer. I just baby-sit the computers. They do all the stabilization. I sit in a room on the 180th floor and read science fiction on the Web. Hours and hours of mind-numbing boredom punctuated by moments of stark ennui. That's my job, Emma. That's what I do."

He walked to the door, flailed his arms until he caught Emma's attention. She smiled that smile. "Yes, I'm coming straight home, Em. Yes, I'll pick up milk." She could smile him into abject submission.

"Be careful," she signed, "Mother sends congratulations."

Barry signed back "Ha ha," then a quick, "Bye. I love you."

Agitated and working on the beginnings of depression, Barry walked the fifteen minutes to the CityRail station in half that time, passing rows of terrace houses without seeing. He caught the first train to the city, getting off at Redfern. The Murdoch Tower had transformed the seedy fringe into the tony heart of a "new Sydney," making the Aboriginal Housing Council that owned the land one of the richest and most powerful groups in the state.

Locals referred to the Tower as "Isaac" because of the big ISSC sign on the 60th floor. You had to be on the harbor to read the name on the 250th, and even then you needed good eyesight and a smog-free day. Isaac was Sydney's answer to the Victoria Tower in Melbourne, and it was the tallest building in the southern hemisphere by a trick of design. The Murdoch Tower started some forty meters off the ground.

Barry braced himself as he crossed the cream-and-ochre plaza to the bank of lifts. It was always windy under the Tower, but a Southerly Buster had come in, a typical Sydney-style blow that sent hats flying and boats scurrying for safe mooring, and it fairly screamed between the pillars.

Barry could still remember the dizzying feeling the first time he had seen them. The Tower was still under construction then, festooned with staging and tarpaulins and stabilized by a network of thigh-thick cables. Rising from the clutter of temporary structures scattered across the plaza were the columns that held the building aloft, gigantic beams of plascrete shining in their bright ferrallium jackets. He had stared until his neck had ached, watching construction workers disappearing into the bottom of the building ten stories above.

The ugly cables were long gone now, replaced by a legion of computer-controlled devices-- tension cables, hydraulics, and mass dampers--that kept the underweight building balanced on its stilts. Computers sensed the changing wind, the shifting weight of occupants, the ripples of an earthquake aftershock, even minute changes in local gravity. The computers pushed and pulled, making the building bob and weave in precisely choreographed responses to myriad influences. To Barry, it always looked precarious, perched on those twenty-five pillars, as if it could topple in the slightest breeze, which is exactly what it would do were it not for the triple-redundant stabilization computers he monitored.

Out of unalterable habit, Barry scanned the plaza as he rode one of the transparent lifts into the base of the Tower. Just before his bubble was swallowed by the first floor, a dull flash of red caught his eye. Lasers shining down the central columns monitored alignment. The flash meant the building was perceptibly off center. Numbers danced through Barry's head as he tried to figure just how far off.

He hurried across the lobby to the express service lifts and waited impatiently for the security system to finish its dialogue with the box in his tool bag. The doors slid open and Barry slid in. Immediately linking into the building system with the palmtop from his bag, Barry started paging through the kaleidoscope of graphic data as the lift whistled upward. At 180, he wedged himself through the widening crack of the opening doors and stormed into the Stabilization Room.

Fiona and Malcolm took no notice. Eyes fixed on their screens and wrists deftly flicking matching joysticks, they were intent on other crises. Entire civilizations were disintegrating before the alien onslaught on their screens as yet another game of Barzakon Invaders played out.

"What the shit is going on here?" Barry barked.

Mal looked up for a moment, then turned back to his screen in time to see his H-Class cruiser vaporized into fractal dust.

Barry snorted. "You have tensors red-lining on 70 and 81, one hydraulic damper is leaking fluid all over the substation floor, and you two are playing computer games."

Fiona reached with her free hand and casually tapped her keyboard. The display shifted from far off galaxies to a schematic view of the hydraulic system. She ran a finger over her sketch pad, highlighting a shunt line on the display, then switched displays and keyed the two overheated tensors off line with a time out.

"No worries." She wrinkled her nose at him and returned to the game, only to find her "enemy" had vanished. "Look, Barry, do your fusspot bit on your own shift. We're still on duty for eleven minutes. The building, she'll be right."

Barry couldn't stay angry at them. The problems with the tensors and the hydraulic damper were not serious. Still, he couldn't help wondering what was going on. He busied himself at the spare console until Fiona and Malcolm sheepishly handed over the log card when Anya arrived.

"Real fence lifter blowing out there," Anya said as she pulled the wool jumper over her head. "How ya going, Bazza?" He looked up. Asian and Mediterranean strains mixed pleasantly in Anya's intelligent face, but she was as Australian as wombats and wallabies. "You right?" she asked.

"Take a look," he said, calling up the pages he'd assembled. Although he was shift supervisor, he always deferred to Anya. An ex-programmer with a quick mind, she was, like Barry, working below her abilities. Between them was a friendly frisson that Barry had always assumed had a sexual subtext.

"What's your point?" she asked. "Looks like we're pulling some extra power, the counterweights in sub three have been swinging, and several tensors are temporary bludgers. Not a problem." She patted his shoulder. "Go back to your book, Barry."

They were nearly three hours into the shift before she interrupted. "Hey, Bazza, you better come back from Cygnus and take a look. Check out the screens while I bring up the doco."

It was pretty obvious. Barry watched the central display as an array of twenty-five red circles superimposed on yellow ones slid slowly to one side, then the other. Another screen showed the Southerly Buster still blowing hard, with gusts over the upper stories first adding to the force, then countering it. The building was oscillating.

Anya looked worried. "I thought it wasn't suppose to do that."

"It's not the building," he said, scratching his chin. "The periods are wrong. The building couldn't sashay like that on it's own. It would just whip slowly back and forth or ripple. It must be the computers. The winds are interacting with the control programs in a way they weren't designed to handle."

She didn't hesitate. "Then we need to get into the programs."

He looked shocked. "You're crackers, that's an expert system. Why do you think they call it that? We're not authorized. We wouldn't know what to change if we were."

"A program's just a program. And experts are just blokes, too. Look, I need your passcode to access those files. I can do it. I'm a good programmer, even if I'm not licensed."

"No," he said. "We play it by the book."

They followed the book for half an hour, rerouting power, plugging in spares when servos overheated, and cranking up the hydraulic pumps. The readings kept creeping toward the limits. Anya tried several times to reach the Building Master at home, but there was no answer.

Reluctantly, Barry keyed in his passcode and nodded to Anya, who started silently scrolling through page after page of the rule-base statements, trying to make sense of them, waiting for something to leap out at her. Finally she spoke. "I don't think we can do it this way. This here interacts with that. I don't know what any of this is about. And that one's Greek to me," she said, pointing to a line that started out with a lambda and ended with a rho.

Barry groaned. "Okay, what next, mate?"

"We have to take over."

"Now you really are talking crazy. Those are sophisticated control programs running on fast computers. You have to process thousands of readings a second and adjust systems on three hundred floors. You can't possibly handle that."

"No," she said as she held his eyes. "You're the pilot. You fly the thing."

He thought for a moment. It didn't make sense. If the control programs couldn't manage, a human was doomed.. "No way." 

She crossed over to his chair and crouched beside him. "Those programs aren't working and they aren't going to suddenly get any better while we debate this. We have maybe an hour before this thing falls over."

"Then we pull the Evacuation Alarm, Anya." Even as he said it, he knew it was no go. It would take hours to clear the building. At the end of the day, the Tower would still be spread most of the way to Darling Harbour.

"Dammit, Barry, if we don't take control, a lot of people are going to die. OK, yeah, if we stuff it up, they will anyway. Either way, you and I come down hard somewhere around Haymarket. So we have to give it a fair go. Just show me how to access the low-level control programs that interact directly with the tensors and stuff."

He clenched his fists, his hands shaking visibly, but his voice was calm. "No, I should do it. I'm the shuttle jockey."

"It's not like flying a shuttle." she said. "You only get one chance."

"Then it is like flying the shuttle. It was a deadstick landing with those birds. No power, one pass."

I only stuffed it up on one mission, he told himself as he stared at the console for a minute. "This won't work," he said, pushing his chair back, "not from a keyboard and sketch pad."

"You're doing that again. That thing with your hands," Anya told him.

He looked down at his hands, clenching, unclenching, grasping at nothing. He remembered the shuttle cockpit, with controls suited to the task. He closed his hand around an imaginary something protruding from the arm of his swivel chair. "I really need… Hey, give me those!" He pointed to the joysticks still sitting on Anya's console. "No, both of them."

They were the latest from Microsoft, heavyweight four-axis beauties with four finger-operated mode switches in the handles plus big "fire" buttons on top. He released a latch on one, twisting and reseating part of the handle. "There, left and right." He set them down on the console in front of him, one for each hand. "Now, get back to your console and show us how good a programmer you are, because we're going to have to bypass a lot of safeties before we can even start reprogramming."

Anya and Barry worked furiously, nervously glancing up at displays that painted an ever worsening picture. Finally he told her to patch the joysticks in just below the expert system.

"What should I connect up?" she asked. "How do you want the displays?"

"How the hell should I know? You think I do this every day? Make reasonable choices and I'll figure it out. Just give me real-time control over as much of the building as possible."

She sat staring at her screen, shaking.

"Look, its just a matter of requisite variety," he said calmly.

"What?"

"The Law of Requisite Variety. General systems theory? Ross Ashby?" She continued to stare at him blankly. "Finite state machines?" Her mouth formed a confirming "oh" but without understanding. "Just means that you gotta have more internal states or degrees of freedom than the environment you want to control. Otherwise it controls you. It means flexibility wins. So just hook up whatever you can in some way that makes some kind of sense. We have eight-bits off the mode switches to give me zone control. Be creative. You have four axes of analog to play with. And give me feedback, visual feedback on whatever is going on. Don't worry about it, just do it!"

Anya brought up the visual compiler and started pulling together components. New displays lit up the monitors. Barry twitched his fingers and subtly moved his wrists, watching as shapes twisted and turned, lines lengthened and shortened, hues shifted down the spectrum.

"You're brilliant. How did you do that one?"

"I just computed the streamlines from the wind sensors. What about that plan view with all the floors superimposed?"

"Cool. All right, let's go live." He hesitated for an instant, then punched a key and quickly grabbed the joystick again. As he twisted his left hand, a sparkle of pixie dust bloomed over a tensor at the bottom of one screen. "What was that?"

"That means it overheated. You said be creative."

For a time it seemed that Barry was keeping up, then the swings started increasing again. More systems red-lined, and one entire floor went dead.

"Pull it Anya, pull it! I'm losing it." The building shuddered. "We can't save them all, but some on the lower floors may get away. I'll hold it as long as I can. The police may be able to evacuate Central Station."

Anya flipped the cover off the alarm. One hand on the red lever, she started to slide the safety out with the other.

Barry raced through end-game scenarios, wondering if he could at least make the building break up as it fell instead of going over like a tree and taking out a kilometer-long swath of Sydney. In his mind's eye he had an unreal image of a wildly bucking building just before final collapse. It reminded him of something he'd seen in engineering school. Tacoma Narrows.

"Wait!" he screamed, just as the safety slid free. "I'm trying one more thing." It was a long shot.

He started rocking his hands in a slow, complex rhythm, concentrating, listening, shifting his eyes from monitor to monitor. Gradually, the displays changed. Squares rotated, then twisted back. Angry red bars lengthened on several screens. An entire bank of tensors sparkled as they shut down. "Override those thermal protectors," he called to Anya.

The building groaned, and Anya's coffee mug slid against her keyboard. "Jesus, what are you trying to do?"

"Shut up. I'm flying this thing."

Barry kept rocking the joysticks, being careful not to over-react. He tilted his head, listening, eyes slightly out of focus, sensing the building's responses. Instinctively he began to change his moves, holding the joysticks an instant longer in one position. Keep it steady, he thought. It took a kind of relaxed tension, crisp responses without jerking the controls. Anticipate, he told himself. Take the lead. Listen to what the building is telling you.

The building complained. The complaints grew louder.

"God, Barry, 156 and 157 are damned close to structural failure. Above 225 they have no power. The cables must have snapped." They could hear running steps in the stairwell. In the monitors, people could be seen spilling into the plaza below the Tower, streaming away in panic. "What in hell are you doing?"

"Making this building act like a bridge, Tacoma Narrows, to be exact."

"Shit, no. Wasn't that the bridge that started bouncing in the wind like a bad mattress and shook itself apart? Is that what's happening?"

"No. This is different. We're a cantilever, not a suspended beam. We're flapping in the breeze, which is the problem. We need to twist in the wind. If we convert some of the energy into torsional mode oscillation, we can stay centered over those columns. It's Terpsichore. I'm just teaching this thing to do the twist instead of the bump." Her brow creased. "Sorry, a lame reference to the tribal dances of ancient Americans." An explosion of shattering glass interrupted him. "Just give me ten minutes before you hit the alarm," he shouted above the wind and the rising noise.

Twenty sweaty minutes later he told Anya to switch back to programmed control. They sat, holding hands, shaking, alert for signs of trouble.

By the time their shift ended, repair crews and television people were swarming all over the building. They slipped past an ABC crew, then rode down the service lift without talking. It wasn't until they reached the now litter-strewn plaza that Barry spoke.

"Tell me, how did you lose your programming license?"

"Never got it. I hate tests. I never even sat for the HSC. I ran away to Ireland instead of going to uni. That's where I picked up Eiffel and VB. I still sell stuff over the Net to people who care more about the quality of the code than the parchment. Besides, I'm coming to like this stabilization engineering stuff. What about you? Why don't you fly anymore? You could join one of those clubs, do it on weekends."

He laughed. "Now what the hell would I want to do that for, wasting my weekends flying. I get enough of that during the week." He grinned as he patted one of the columns, then turned toward the rail station.

The wind had died down some. Barry slipped on his gloves, dialed with a quick flutter of fingers, and started signing a message for forwarding to Emma. "It was a good landing. Flexibility wins. Be home in half an hour. I love you." He held the last three-finger sign a long time before adding the signature: "Tower Jockey."