Reverse engineering of integrated circuits, 1970s style

We’re used to the reverse-engineering stories of integrated circuits in these pages. Some fascinating presentations of classic chips were produced by people such as the Ever Hard Worker [Ken Shirriff].

You might think this practice would be something new, reserved only for those interested in how the now obsolete silicon works. But the secrets of these chips were closely guarded by business intelligence at the time, and there was a small industry of experts whose life came from unlocking them.

Electron micrograph of a wire link to the Z80 CTC chip

Integrated Circuit Engineering Corporation was a Scottsdale, Arizona-based company specializing in semiconductor industry data. They have long been engulfed in a series of corporate buyouts, but we have a fascinating window into their activities as their records are held by the Smithsonian Institution. They reverse engineered integrated circuits to produce reports containing detailed information about their mechanical properties as well as how they function, and it is precisely this report that is our topic today. Their 1979 review of the Zilog Z80 CTC (PDF) begins with an examination of the packaging, in this case the more expensive ceramic variant, and then examines in detail the internal construction of the die itself and its connecting threads. We are then taken into its typed pages through an in-depth circuit analysis on the die, with gate-level circuits to explain how each part works.

The detail in this report is extraordinary, it is clear that a tremendous amount of work has gone into its production and it would have been of tremendous value to some of Zilog’s customers and competitors. At the time, this would have been extremely commercially sensitive information, although it now appears to be a historical curiosity.

The Z80 CTC is a 4-channel counter / timer peripheral chip for the successful Z80 8-bit microprocessor, in a 28-pin dual in-line package. We were surprised to find, on a quick research, that you can still buy this chip from some of the regular suppliers rather than surplus homes, so it may even still be in production.

If reverse engineering of integrated circuits appeals to you, take a look at our archives of [Ken Shirriff] posts.

Thank you [fortytwo] for the tip.


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