Product testing on Various versions of hardware.

How would you test a product for various versions of hardware.
Would you compile SRS for general features testable for all versions under one header and specific features to particular Version under another header?
OR
Would write all the SRS and test cases under one single Version based Header either those SRS were common or version specific?
How would you optimally write SRS to reduce efforts in testing while avoiding redundancy and keeping in mind if a particular version gets obsolete then it would easier to delete corresponding SRS from single header?.