1TB internal hdd, computer's memory only has 111GB

Brillis Wuce

Distinguished
I think you're looking at your SSD. A 120GB SSD will actually have about 111GB of actual space.

Sounds like your 1TB just doesn't have a letter assigned to it.

Start < Right click on My Computer < Manage < Disk Management < Look for around 930GB of unallocated space < Right click on it < Assign Drive Letter and Path
 
You're reading the 111GB as if it was the 1TB drive. It's not. It's the 120GB SSD which, as with all drives, never allows full use of the entire storage space. Some space is simply averaged, and is not actually that size, and some remains reserved for the system. 111GB of a 120GB drive sounds about right.

Apparently, you are either not understanding that there are two separate drives installed, or something is configured incorrectly and the 1TB drive, which will be a secondary drive and should be used for storage and repetitive data that will often be written to the disk, in order to maximize the longevity of the SSD.