Knowing that TI has a habit of turning early specimens into VSC units, I'm intrigued by the 81 VSC units attached to LTA90 screens that show up every now and then on ebay. But aside from LTA90 possibly indicating 1990 and the lack of the ON bar, there's no further indication of what's inside.

Datamath has a page on the old tethered TI-81 VSC, but I could not find any board pics of it. The mention of a T6A43 ASIC and a 1991 ROM seems unusual for ROM 1.1(K) and a lack of the "bar" below ON.

Before I consider buying one to disassemble (they're not as cheap as I hoped), has anyone seen what's inside a LTA90 TI-81?

I've been meaning to buy one for some time to have a look - but postage to where I live is huge compared to the actual item.

I did not know about early specimens -> VSC units however!

LTA indicates the device (which would be the ViewScreen peripheral) was manufactured in TI's Lubbock, TX facility. We see this with early CBLs. A suffix of 90 would indicate that the ViewScreen peripheral was manufactured in 1990, but usually these datecodes are in the format LTAwwyy, which includes a week number; with only the year, we'll have to rely on PCB and IC datestamps to figure out when the base calculator was assembled in Taiwan.