The Collaborative International Dictionary of English v.0.48:

Amb- \Amb-\, Ambi- \Am*bi-\ [L. prefix ambi-, amb-, akin to Gr.
   ?, Skr. abhi, AS. embe, emb, OHG. umbi, umpi, G. um, and also
   L. ambo both. Cf. Amphi-, Both, By.]
   A prefix meaning about, around; -- used in words derived from
   the Latin.
   [1913 Webster]

V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

AMB
       Advanced Memory Buffer (IC, RAM, FB-DIMM)