I currently have three Symbolics MacIvory CPUs. (Do you, reader, have one to sell? Please leave a comment!)

One is currently installed in a working machine and was not yet molested; the two remaining chips, I obtained in 2017 by bartering away a Symbolics 3620.

At some point I will cut one or more of the "Ivories" open, and perform die microscopy. But prior to this, why not a bit of non-destructive imaging?

The first of the two samples is a "production" model, with a metallic cap:

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Edit: the bottom side of this unit looks like this.

An attempted die shot at maximum voltage yielded:

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It appears that 35kV (the maximum setting of the system) is unable to produce a usefully-contrasting image of the die and connections.

So we move on to the second sample, a "proto" model with a ceramic cap:

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And with this one, we get:

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Pretty interesting. What is the substance visible on the die? (glue holding the lid in place? or a "bird's eye" view of the metallic layers of the die itself?)

Later, a magnified shot will be taken of this unit, with 35cm film and a scintillation cassette.

Exposure: 75 sec. @ 35kV, contact print, film: "Eco-30".