Igano,   The only supported OS for the N1500 series is OS6, but if you were wanting to get eyes on that information it is displayed under show tech-support. Let me know if this helps.
Hello Quick question. I'm investigating the use of ansible with DELL switches N15xx series. I found some documentation online where it is asking you to find the OS version of the switch. Is the OS version the same as the firmware version? My firmware version is 6.7.x.x. Does that mean my OS is 6?  Many thanks
How to find out switch OS version