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τ=t1−t0log⁡2 ⁣(B1/B0)=2025−2022log⁡2(2.0/0.82)≈2.3 years\tau = \frac{t_1 - t_0}{\log_2\!\left(B_1 / B_0\right)} = \frac{2025 - 2022}{\log_2(2.0 / 0.82)} \approx 2.3 \ \text{years}

Why this formula appears here

where B0B_0 is the bandwidth at reference year t0t_0 and τ\tau is the doubling time implied by the data. Solving for τ\tau from the two JEDEC anchor points gives τ=t1−t0log⁡2 ⁣(B1/B0)=2025−2022log⁡2(2.0/0.82)≈2.3 years\tau = \frac{t_1 - t_0}{\log_2\!\left(B_1 / B_0\right)} = \frac{2025 - 2022}{\log_2(2.0 / 0.82)} \approx 2.3 \ \text{years}. Extrapolated naively, ten more years at that doubling time — roughly 4.3 further doublings — would put per-stack bandwidth near 39 terabytes per second by 2035. That number should not be believed as stated, and the reason it should not be believed is itself the analytically interesting point. A two-point fit is not a trend; it is a line drawn through the only two data JEDEC has actually ratified. And it runs well ahead of the general DRAM-and-interconnect bandwidth scaling documented across two decades of hardware by…

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B1B_1

Symbol B_1

B1B_1 occurs below the fraction bar. The quantity above the bar is divided by this expression; zero is excluded as a denominator.

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log⁡2 ⁣(B1/B0)\log_2\!\left(B_1 / B_0\right)

Denominator: log_2(B_1 / B_0)

The complete quantity below the fraction bar; it must be nonzero for this division.

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log⁡2(2.0/0.82)\log_2(2.0 / 0.82)

Denominator: log_2(2.0 / 0.82)

The complete quantity below the fraction bar; it must be nonzero for this division.

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With a fixed numerator, increasing a nonzero denominator reduces the fraction. Its accuracy depends on the assumptions and range of use described in the article. Read it with the definitions, units, and assumptions supplied by the article.

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Published contexts (1)

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τ=t1−t0log⁡2 ⁣(B1/B0)=2025−2022log⁡2(2.0/0.82)≈2.3 years.\tau = \frac{t_1 - t_0}{\log_2\!\left(B_1 / B_0\right)} = \frac{2025 - 2022}{\log_2(2.0 / 0.82)} \approx 2.3 \ \text{years}.

Equation 6 · Semiconductors

AI Memory Systems and the Bandwidth Wall in 2035: Scenarios, Signals, and Falsifiable Predictions

This equation gives an approximation: it relates the quantities while allowing an approximation.

where B0B_0 is the bandwidth at reference year t0t_0 and τ\tau is the doubling time implied by the data. Solving for τ\tau from the two JEDEC anchor points gives τ=t1−t0log⁡2 ⁣(B1/B0)=2025−2022log⁡2(2.0/0.82)≈2.3 years\tau = \frac{t_1 - t_0}{\log_2\!\left(B_1 / B_0\right)} = \frac{2025 - 2022}{\log_2(2.0 / 0.82)} \approx 2.3 \ \text{years}. Extrapolated naively, ten more years at that doubling time — roughly 4.3 further doublings — would put per-stack bandwidth near 39 terabytes per second by 2035. That number should not be believed as stated, and the reason it should not be believed is itself the analytically interesting point. A two-point fit is not a trend; it is a line drawn through the only two data JEDEC has actually ratified. And it runs well ahead of the general DRAM-and-interconnect bandwidth scaling documented across two decades of hardware by…

Meanings in this article

  • τ\tau: the doubling time implied by the data.
  • B0B_0: the bandwidth at reference year t0t_0.
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