Warren Abstract Machine

Prolog's WAM, a concrete VM to support efficient Prolog compilation.

1983-1993: The Wonder Years of Sequential Prolog Implementation, Peter Van Roy, May/July 1994, Journal of Logic Programming. A survey of implementation technology and systems since the WAM.
Hassan Ait-Kaci, Warren's Abstract Machine: A Tutorial Reconstruction (a .ps under Reading list), MIT Press, 1991 (a copy from the Vancouver XML Developers Association (VanX), .html [MIA]). The book is out of print, but its contents are on-line.