A modern processor can’t afford to wait for certainty.
Lin Tao paced along the southern boundary of the white chamber. His boots struck the floor in measured, clockwork strides. In complex system architectures, when the execution pipeline encounters a conditional branch order—such as testing whether an index is within legal bounds—evaluating the condition can need dozens of cycles. Meanwhile, the relevant data is fetched from memory.
If the processor waited for the result before fetching the next order, the execution units would sit idle, wasting calculating throughput.
To maintain maximum processing speed, the Precursor CPU used risky execution.
Using specialized branch prediction hardware—typically a Two-Bit Saturating Counter or a global history pattern matcher—the processor guessed which path the branch would take based on past history. It speculatively carried out the instructions along the predicted path, calculating results, dereferencing memory addresses, and staging data before it even knew whether the branch condition was legally valid.
If the guess was correct, performance surged forward without delay.
If the guess was wrong, the processor discarded the speculatively calculated results, rolled back its registers, and resumed execution along the correct path.
Lin Tao paused at the southwestern corner, turning to face the open void.
