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1985年,也就是在80386推出之前CPU对内存的访问总是以实模式的方式,即第64K一个分段,而80386的推出使PC机的内存访问方式有了一些变化。在The Intel 8088,Intel 8086,80188和80186中只有实模式,在实模式下寻址方式只能使用段地址+偏移量的方式,内存空间只有1MB,4个段寄存器。80386中加入了两个新的段寄存器。至于使用哪个寄存器,取决于操作指令的前缀。在80386的在保护模式下,内存的访问方式有些类似于IBM S/360,使用地址+索引寄存器+比例+
In 1985, before the 80386 was introduced, CPU access to memory was always in real mode, a 64K segment, and the introduction of the 80386 brought some changes to the PC’s memory access. In The Intel 8088, Intel 8086, 80188 and 80186 only real mode, in real mode addressing mode can only use segment address + offset mode, the memory space is only 1MB, 4 segment registers. 80386 added two new segment registers. Which register to use depends on the prefix of the operation instruction. In the 80386’s protected mode, the memory access is somewhat similar to IBM S / 360, using the address + index register + scale +