Preemptive analysis, consulting, and planning

Can we make our own CPUs?

Posted Friday, April 11 by Marc Abel

It is disheartening to dream of writing secure software—well organized, succinct, thoroughly validated operating systems and applications—knowing it would have to run on silicon with irreparable, undisclosed, and often deliberately introduced vulnerabilities. I propose a “supply chain firewall” for CPUs and systems that can shield (to a large extent) their purchaser or end user from the mistakes, misdeeds, and misaligned interests of semiconductor manufacturers.

A semiconductor plant costs 1 000 times as much as a pick-and-place assembly line, yet either can build a CPU. CPUs made in a “fab” are cheap in large runs, tiny, and perform computations at great speed. In contrast, CPUs soldered from smaller ICs allow superior process oversight during design and assembly, ability to inspect finished CPUs that does not exist with single-chip processors, affordability in even one-off lots, and more options with respect to assembly plant ownership and siting.

In the course of some graduate study, I have been researching the design of end-user-built CPUs, with particular emphasis on arithmetic logic units, or ALUs. The following resource is a snapshot of the work I have done to date, with a lot of technical intricacies to help newcomers to this technology come up to speed quickly. I will be giving a talk about this work in the near future, probably online on account of present conditions. Once the date and time for this talk are known, I will post an invitation on this page.

Elegant ALUs from Surface Amount SRAMs
Marc W. Abel
Department of Computer Science & Engineering
Wright State University
2020 PDF

ALU simulation software released

Posted Sunday, May 24 by Marc Abel

The reference ALU described in the above PDF has been modeled and tested in a C simulation. A tarball is available here.

This is a work in progress, but 109 opcodes do work now and have separately-designed regression tests. Some of the firmware does not exactly match the April document due to errors which have since been uncovered and corrected.


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