RAM : 1568 / 1568 steps with OR-1E module.  Very rare, this model, designed for japanese schools is an intermediate machine between the DB-100 and FX-700p  As PB-100, it has only 544 program steps and accepts a memory extension of 1kB.  As FX700p, it has the F-key for direct access to mathematical functions.  No other details about this model on the web, neither photo of the box neither of the manual.