According to the T90 manual the DMB 90 can store and then display various pieces of data for each exposure on an LCD panel on the back.
Can also imprint some of this data on the film, manual doesn't say where. I.e. in the image area or elsewhere.
With the interface unit DMB all data can be checked, (stored), on an MSX personal computer.
Quote 'Data Memory Back 90, Interface Unit DMB and MSX computer are not available in North America and some other areas.' /Quote
See Wikipedia for description of MSX computer from the mid '80s to 1990. Very basic and mainly sold in Japan, S.E. Asia, South America and some European countries.
I don't see that it's of much practical use today, depending on how the data printing is handled. It may be a challenge to get an MSX computer up and running seeing as how they went out of production around 1990. The OP may just like one to round out a collection of T90 accessories.