指令系统

多媒体扩展指令集，用于提升计算机对多媒体的处理能力

回绕算法，饱和算法（溢出后的多媒体处理）<br>

CISC：复杂指令系统计算机

RISC：精简指令系统计算机

<div>RISC较CISC的优点：充分利用芯片面积；<br>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 提高计算机运算速度；<br>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 便于设计，降低成本，提升可靠性；<br>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 有效支持高级语言；<br>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 耗能少；<br>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 优化编译技术；</div>

<div>操作码扩展<br></div>

包含：源操作数地址、目的操作数地址、下条指令地址

<div>四地址指令，三地址指令，二地址指令，一地址指令，零地址指令</div>

立即寻址：操作数在指令字中<br>优点：方便快速<br>缺点：限制立即数范围

<div>寄存器寻址</div>

<div>存储器寻址</div>

<div>基址寻址（内容由操作系统确定）</div>

<div>变址寻址（内容由用户设定）</div>

<div>相对寻址&nbsp; P227</div>

<div>堆栈寻址（零地址指令）</div>

<div>中缀表达式、后缀表达式</div>