When buying generators for camping etc.... take a read of this
Honda Inverter Produces Power Stability
Computers and power-sensitive testing equipment require what is referred to as "clean power." Clean power is electrical current that is consistent and has a stable "sine wave" or signal. If the lights or other basic appliances in your home were being powered by a generator and there was a fluctuation in the AC power, you’d probably see the lights dim and then return to full brightness—no problem! However, if your computer was being powered by a generator and the voltage fluctuated, chances are the computer would either shut down or at least interrupt the program you were working in.
In order to overcome this problem, Honda engineers developed a revolutionary form of inverter technology. This process takes the raw power produced by the generator, passes it through a special microprocessor that provides ultra-clean power that boasts a sine wave equal to or better than the current from your household AC wall outlet. This means that, you can operate a computer or laptop direct from a generator.
Link
Do not use a modified (or square) sine wave output generator.