Virtual Memory. Invented on Manchester atlas 1962. It embodied many pioneering features, which we now take for granted. These include system features such as, Timesharing of several concurrent computing and peripheral operations, Multiprogramming, and the One-Level Store (Virtual Store).
General Purpose Registers Segment Registers
AH/AL AX Accumulator CS Code Segment
BH/BL BX Base DS Data Segment
CH/CL CX Counter SS Stack Segment
DH/DL DX Data ES Extra Segment
Pointer Registers Stack Registers
SI Source Index SP Stack Pointer
DI Destination Index BP Base Pointer
IP Instruction Pointer
Mov ax, DS:100h
loads word at 100hex in the data segment into ax
adds the word in the Extra segment at the offset in the SI register to the ax register
A selector is loaded into the segment register and triggers the acces to the segment tables
Mov es,ax moves ax to the es register.
< 32 bit
On chip associative page address registers.
This is small, only about 64 of them