How to randomize equally for multiple segments?

Hello!  

I am writing a survey where I’ll have 4 segments by device type and will create a variable to categorize them.  There will be 25 per segment.   

I also need to show two different question sets to half of all respondents.  I’d like each device type segment to be equally divided (can be off one since it’s an odd number) so that I don’t end up with the entire sample being equally divided while the different device types are not.  

I know how to create the variables for the device types and I know how to randomize blocks, but not sure how I can assure each segment is equally divided 50/50 between the question sets.  

Appreciate any thoughts! 

Thanks!