In the UK I came across this FAQ about allowed calculators:
Curious to know which calculators people think might be ok for school children? Superficially I'm thinking the DM-15L or HP-15c would be ok, but not so sure about the DM-42 (because it would be hard to show it is clear and it can communicate) or upcoming DM-32 (due to the solver?).Calculators must be of a size suitable for use on the desk, either battery or solar powered and free of lids, cases and covers which have printed instructions or formulas.
Calculators must not be designed or adapted to offer language translators, symbolic algebra manipulation, symbolic differentiation or integration or communication with other machines or the internet.
Calculators must not be borrowed from another candidate during an examination for any reason.
Calculators must not have retrievable information stored in them, including databanks, dictionaries, mathematical formulas or text.
The candidate is responsible for the calculator’s power supply and working condition.
The candidate is responsible for clearing anything stored in the calculator.
An invigilator may give a candidate a replacement calculator.