I have a question about some vintage hardware

Me and my mom were helping my grandpa clean out his house,and we found a vintage unopened Texas Instruments TI-99/4 and on it,it says "Solid State Software" near where you load the cartridges in.

And i am wondering is it anything like the what is used for modern SSD's?

If not what is the differance?

It just means that instead of tape, you were using "solid sate" memory, in carts, much like Atari carts of the day. Now the moniker "solid state" is in contrast to tape decks being used at the time for data storage.  It was for software, if you are wondering.

im assuming its using eeprom / eprom. not the same method used today, but still technicaly a "solid state" memory.

the only thing im thinking is if it is unopened u could get a pretty penny for that