HP-30b unknown options


I'm exploring my 30b and I hold the PMT button and turn the unit on. I see Tst Screen, Tst Keyboard etc. onto TSys Off and Slow Clk.

Does anyone know what Tsys and Slow Clk are, or what they do?

Thank you for any information on this.



Tsys will, if enabled, prevent the calculator from going into sleep mode, which means that it will drain the batteries much faster than usual.


Slow Clk is a way to tell the firmware the actual processor speed which depends on temperature, humidity, and whether it's a holiday or not ;-). The test system has a serial connection, and to make this work a more accurate knowledge of the speed of the system is needed.


Thank you Eric and Marcus for the information.


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