[msephton]

MacOS does memory compression as standard since 2013. Linux has it, and iirc even Windows has it since 10.

[hangonhn]

Didn't DOS have it too?

[duskwuff]

Definitely not. DOS had disk compression utilities, but not RAM - there was no reasonable way to accomplish that at the time.

You may be thinking of "memory manager" utilities like QEMM and EMM386 which tried to maximize the amount of conventional memory available to programs (i.e. below the 640KB boundary). These programs worked primarily by causing drivers and TSRs to run in upper memory - they didn't actually provide more memory.

[alex_suzuki]

So that was what 13yr old me was doing modifying himem.sys to get some stupid game to launch. :-)

[hangonhn]

Oh right! I got disk compression and QEMM and EMM386 all mixed together in my now decades old memory (pun kind of intended) of DOS to produce that false recollection.