“I know what you’re thinking. You wouldn’t trust it to do a third-grader’s multiplication table. But looks can be deceiving — this was the soul of many a college computer lab in the late sixties. And by the time Dr. Silver began serious work on Liza, these were just old enough to be picked up at fire sale prices. Besides, you’re not looking at it from a programmer’s perspective. Remember, Liza’s physical self was never moved — just expanded. So think of this as the spark plug of a vast and very powerful engine.”
Lash looked at the old computer. Spark plug, he thought. And we’re going to pull it.
“Let’s just turn it off,” he said.
Beside him, Silver smiled: a faint smile that sent a chill up Lash’s spine.
“Try,” he said.
Of course. If Silver had gone to such elaborate lengths to safeguard Liza from attack or power loss, he would certainly have disabled all the power switches.
“We won’t be doing anything that crude,” Tara said. “We’re going to run a new program on this old 2420. A program to instruct it to order a stand-down from Condition Gamma. That should restore electricity, open the security plates.” She looked at Silver. “What’s the original computer running now?”
Silver did not return the look. “The bootstrap loader. The back-propagation learning algorithms that seed the neural network.”
“When was the bootstrap loader last initialized?”
Another faint smile. “Over a decade ago. That was the last time Liza was restarted: thirty-two major program releases back.”
“But there’s no reason it couldn’t reinitialize, is there?”
“No reason at all.”
Tara turned to Lash. “Perfect. We can use the old bootstrap routine to load in a new instruction set. This is the core machine, the first domino in the chain. It retains those earliest memories you talked about.”
“So?”
“So it’s time to reacquaint Liza with her own inner child.” She turned back at Silver. “What’s it programmed in?”
“Octal machine language.”
“And how long would it take you to code and keypunch a program like I’m describing?”
“Four, maybe five minutes.”
“Good. The sooner the better.” And Lash watched Tara’s eyes drift beyond the old computer, toward the smoke that was rolling toward them in great gray sheets.
But Silver did not move.
“Dr. Silver?” Tara said. “We need that program now.”
“It’s no use,” came the weary reply.
“No use?” Tara echoed. “No use? Why the hell not?”
“I prepared Liza for every eventuality. Don’t you think I prepared for this, too? There are a dozen simulacra of this 2420, running as virtual machines inside the Cray supers. The program outputs are constantly compared. If there’s any discrepancy, the feed from the others is normalled and the original unit is ignored.”
Tara went pale. “You mean, there’s no way to modify its programming? No way to change its instruction set?”
“None that would make any difference.”
A terrible silence descended on the little group. And — as he stared at the expression on Tara’s face — Lash felt the hope that had surged within him wither and die.
SIXTY-TWO
A thousand feet above the streets of Manhattan, the chamber trembled as countless devices shrieked, pressed beyond their electromechanical capacities, spitting sparks and belching ever darker gouts of smoke. Even from where Lash stood — in relative quiet at the center of the hive-mind — the surrounding sound and vibration were terrifying. He coughed. Sweat was running freely, and his shirt was plastered against his shoulder blades. The shaking had grown so intense it almost seemed the penthouse would rip itself free from its supports and tumble earthward. And as he looked at the surrounding faces — Tara, staring intently at the ancient computer; Silver, desolated and in shock; Mauchly, dabbing at his forehead with a handkerchief — Lash felt that would almost be preferable to waiting here while death slowly approached.
The others began to return. First, Sheldrake, shaking his head to indicate he’d found no alternate escape route. Then Dorfman and Lawson, who reported that, as expected, the backup generator and its power conduits were impervious to any attack they could mount. Last came Gilmore, soot-blackened and wheezing, to say that — while the sprinklers in the upper floors of the penthouse could be jury-rigged — the task would take an hour, maybe more, and would probably be insufficient to quell the dozens of fires that were now sprouting up all around them.
“An hour,” Sheldrake said through gritted teeth. “We’re lucky if we have ten more minutes. It’s got to be a hundred and twenty in here, at least. Those battery cells could go at any time.”
Nobody had a response to this. The air was growing so hot, the smoke so thick, Lash found it nearly impossible to breathe. Each time he drew in air, sharp needles filled his lungs. He felt his head grow light, his concentration slip.
“Just a minute,” Tara said. She had stepped forward and was standing directly before the control surface of the IBM 2420. “These buttons. Each one is labeled with an assembly language mnemonic.”
When there was no response, she looked over her shoulder at Silver. “Isn’t that right?”
Silver coughed, nodded.
“What are they used for?”
“Diagnostics, mostly. If a program didn’t work, you could step through the opcodes, sequentially.”
“Or enter new instructions by hand.”
“Yes. They’re an anachronism, a holdover from an earlier design.”
“But they do allow access to the accumulator? The registers?”
“Yes.”
“So we could run a short instruction set.”
Silver shook his head. “I’ve already told you. Liza’s defenses won’t accept any new programming. Any input from the card reader or keypunch would activate a security alert.”
“But I’m not talking about entering a program.”
Now Mauchly turned to look at Tara.
“We wouldn’t input anything from a peripheral. We’d punch in a few opcodes, right here. Five — no, four — should be enough. We’d just run those four opcodes, over and over.”
“What four opcodes are those?” Silver asked.
“Fetch the contents of a memory address. Run a logical AND against those contents. Update the memory address with the new value. Then increment the counter.”
There was a silence.
“What’s she talking about?” Sheldrake asked.
“I’m talking about accessing the computer’s memory in the most primitive way. Byte by byte. Doing it manually, from the computer’s own front panel.” Tara glanced back at Silver. “The 2420’s an eight-bit machine, right?”
Silver nodded.
“Every location, byte, in the computer’s memory has eight bits. Okay? Each of those bits can have one of only two values: zero or one. Together, those eight binary numbers make up a single instruction, a word in the computer’s language. I’m talking about zeroing out all those instructions. Leaving the computer blank. Instructionless.”
Sheldrake frowned. “How the hell could you do that?”
“No, she’s right,” said Dorfman, the security tech. “You could ‘AND’ a zero byte against each memory location, in turn. It’s almost elegant.”
Sheldrake turned to Mauchly. “You know what they’re talking about?”
“AND is a logical instruction,” Dorfman went on. “It compares each bit to a value you furnish, and either leaves that bit alone or swaps its value, depending.”