Not sure there's a question there. Are you asking why your system only reports 896 when you have 1Gb installed? Unfortunately you have left us guessing as to what you have for hardware but from here, the answer seems apparent.
1Gb = 1024 Mb
1024 - 896 = 128Mb
128Mb is a typical size chunk of system RAM on-board graphics systems snag and dedicate for graphics processing. So my guess is you have on-board graphic, and this is normal.