[ksarul]

The stacked chips are the speech ROMs, as you suspected--and they are a proprietary chip. I may have the specs on them (I'll have to check one of my TI notebooks at work tomorrow). The speech chip is similar to a TMS5220 (it is marked as a TMS0385, IIRC). There are some differences, but they are minor. I finally acquired a copy of the speech chip manual a couple of years ago from one of the original TI engineers. Until that point, the document was considered lost. The one for the TMS5220 is easy enough to find though, so it was not a major issue.