Allen Kent & James G. Williams 
Encyclopedia of Microcomputers [PDF ebook] 
Volume 1 – Access Methods to Assembly Language and Assemblers

"The Encyclopedia of Microcomputers serves as the ideal companion reference to the popular Encyclopedia of Computer Science and Technology. Now in its 10th year of publication, this timely reference work details the broad spectrum of microcomputer technology, including microcomputer history; explains and illustrates the use of microcomputers throughout academe, business, government, and society in general; and assesses the future impact of this rapidly changing technology."