Sharp EL-8200 financial calculator questions

[robve]

The Sharp EL-8200 financial calculator from 1975 is a simple TVM and margin calculator.

   

What interested me in this calculator is the unusual key layout. It also has "TL", "Trend" and "n,x,x2" keys. Note that there are no EXP and LOG keys. As suspected, this calculator cannot solve for "n" or interest rate "i".

I could not find much information about this calculator online. Some things are easy to figure out. The ENT key enters a value into a register. The COMP key calculates. The COMP key also serves as a Shift key (aka F or 2ndF key). To recall (READ) a register, press ENT twice or COMP ENT will do.

But what about the "TL", "Trend" and "n,x,x2" keys? These apparently add data, because "n" increases by one and other registers are updated.

Does anyone on this forum own this machine with an instruction manual? I wonder what operations these "TL" and "Trend" keys perform?

- Rob