Friday, December 1, 2017

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 #
315-557114
315-557215
315-557316
315-5672217
315-5673214
315-5674218
315-5677211
315-5677A215
315-5678212
315-5679A213
315-5679B216

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 #PartDecap #
315-5571MB8623314
315-5572MB8623315
315-5573MB8623316
315-5672CG24 ULA217
315-5673CG24 ULA214
315-5674CG24 ULA218
315-5677MB86234211
315-5677AMB86234215
315-5678MB86234212
315-5679AMB86234213
315-5679BMB86234216

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.

Enjoy this post? Please support us on Patreon! Note: with the Indiegogo campaign over we unfortunately don't currently have a way to accept one time donations.