DUDEK Emil: Boards: The keyboard assembly (E306 36360 GK320-2 GICO Japan) sits loose on top of the main board and battery compartment and is joined by 14 strong wires. The whole board assembly sits loose in the calculator. Construction: Very difficult to open without doing some damage. Gently push in the rear section sides whilst carefully popping the lugs down each side. The front section will hinge off the top. Do not force it, it took me ten minutes of gentle pushing and squeezing to open it without damage! Logic comments: The [CE]-key is used to clear the last entry whilst the [C]-key clears the whole calculator. Overflow on the input of a number is suppressed, typing in a ninth digit is ignored. There is automatic constant on multiply and divide only. Negative numbers are flagged by a minus sign in the far left (ninth) digit thereby allowing full eight digit negative numbers. Divide by zero shows zero and ‘C’ in the far left (ninth) digit and is not recoverable. Overflow shows the result and ‘C’ (or ‘E’ if negative) in the far left (ninth) digit and is not recoverable. Negative square roots are not allowed and result in the answer with an ‘E’ overflow which is not recoverable. The change sign function can be used in mid number entry.