Whitepaper · Notebook 01 · Multi-ISA and binary translation

Running someone else's code

Ten cases between 1994 and 2026 — from PowerPC 615 to Rosetta 2 — and the four contracts framework for reading IBM Z's dual-ISA announcement with three decades of context. Twelve pages.

Cover of the notebook Running someone else's code

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What you get

The four contracts a foreign binary has to honor before it reaches production.

Why did PowerPC 615 die before reaching the market while Rosetta 2 worked in 2020? What is IBM repeating that had been tried before? And why Arm, not Power?

On 24 August 2026 IBM announced that every core of its next mainframe processor will run Arm alongside z/Architecture. The headlines stop at the hardware, and the hardware is the small part: the CPU executing the binary is only the first of four contracts.

This notebook accompanies the Beyond One ISA series — Part I is already out —: the story of those who tried before, ordered by a framework that holds for this announcement and for the next one.

What's inside

  • The four contracts — instruction, ABI, platform and distribution. The order they close in, and why the fourth has never fully closed.

  • Six patterns that repeat — translation dies with the incentive, whoever controls the release calendar wins, and the kernel is always the boundary.

  • PowerPC 615, FX!32, DAISY, Crusoe, QuickTransit, Rosetta 1 and 2, Prism… ten case files between 1994 and 2026, with the contract each of the dead ones broke.

  • IBM's announcement read through that framework — what the dual-ISA core solves, what stays open, and which public kernel.org patches show it moving.

  • The five questions for IBM — Arm guest drivers, distribution and ISV support matrix, guaranteed CPU profile, commitment in years, and SystemReady. For your next briefing with your IBM rep.

Who this is for

  • Architects and platform teams who will have to take a position on IBM's dual-ISA announcement without having lived the earlier attempts.
  • CIOs and infrastructure leads who want to tell a platform move from a press headline before moving budget.
  • And IBM Z, Power or enterprise Linux teams who want the three decades of context in half an hour of reading.

Published by SIXE, training and services partner for IBM Z, Power and enterprise Linux. This notebook accompanies Part I of the Beyond One ISA series; more reports in the whitepaper library.

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