A: Fundamentals of Single-chip Microcomputer
The single-chip microcomputer is the culmination of both the development of the digital computer and the integrated circuit arguably the tow most significant inventions of the 20th century [1].
These tow types of architecture are found in single-chip microcomputer. Some employ the split program/data memory of the Harvard architecture, shown in Fig.3-5A-1, others follow the philosophy, widely adapted for general-purpose computers and microprocessors, of making no logical distinction between program and data memory as in the Princeton architecture, shown in Fig.3-5A-2.
In general terms a single-chip microcomputer is characterized by the incorporation of all the units of a computer into a single device, as shown in Fig3-5A-3.

單片機是電腦和集成電路發(fā)展的巔峰，有據(jù)可查的是他們也是20世紀(jì)最有意義的兩大發(fā)明。
這兩種特性在單片機中得到了充分的體現(xiàn)。一些廠家用這兩種特性區(qū)分程序內(nèi)存和數(shù)據(jù)內(nèi)存在硬件中的特性，如圖3-5A-1，依據(jù)同樣的原理廣泛的適用于一般目的的電腦和微電腦，一些廠家在程序內(nèi)存和數(shù)據(jù)內(nèi)存之間不區(qū)分的像Princeton特性，展示如圖3-5A-2.
只讀存貯器(ROM). ROM是通常的永久性的，非應(yīng)用程序的易失性存儲器。不少微機和單片機用于大批量應(yīng)用，因此，經(jīng)濟(jì)的設(shè)備制造要求的程序存儲器的內(nèi)容是在制造期間永久性的刻錄在芯片中，這意味著嚴(yán)謹(jǐn)?shù)姆椒?，因為修改ROM代碼不能制造之后發(fā)展。這一發(fā)展過程可能涉及仿真,使用硬件仿真功能以及強大的軟件工具使用先進(jìn)的開發(fā)系統(tǒng)。