Sega 315-5XXX ULAs: #214, #217, #218

In a previous post we mentioned that a few of the Sega 315-5XXX series are special. This brief post documents what we found.

To review, the following chips were lumped together for analysis:

Sega #	Decap #
315-5571	14
315-5572	15
315-5573	16
315-5672	217
315-5673	214
315-5674	218
315-5677	211
315-5677A	215
315-5678	212
315-5679A	213
315-5679B	216

For the most part these were assumed to be a mix of Fujitsu DSPs. For example, here's an MB86233 (315-5571):

While the MB86234 (315-5677) is very close:

So what about the others?

Sega 315-5673 (#214)

Here's the package:

Which has this die:

Which is clearly not one of the DSPs. Markings:

Sega 315-5672 (#217)

Here's the package:

A bit suspicious since it has a wildly different number of pins than the others. Anyway, here's its die:

Which is also clearly does not look like the others. Markings:

Sega 315-5674 (#216)

Here's the package:

Also a different package, it was suspected this wasn't like the others. And here's the die:

Confirming this. Markings:

Summary

These chips are Fujitsu CG24 uncommitted logic arrays (ULAs). With the above new information, our Sega 315-XXXX table now has:

Sega #	Part	Decap #
315-5571	MB86233	14
315-5572	MB86233	15
315-5573	MB86233	16
315-5672	CG24 ULA	217
315-5673	CG24 ULA	214
315-5674	CG24 ULA	218
315-5677	MB86234	211
315-5677A	MB86234	215
315-5678	MB86234	212
315-5679A	MB86234	213
315-5679B	MB86234	216

Summarized as:

• 315-557X: Fujitsu MB86233 DSP
• 315-567X (lower): Fujitsu CG24 ULA
• 315-567X (higher): Fujitsu MB86233 DSP

As there is no firmware to document on these chips, no further work will be done at this time. If at some point it becomes feasible to capture the original layout, we'll revisit.

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