Position data processing machine instructions
| Assembly code | Before the position command data |
|---|---|
| mov bx,[0] | Memory unit ds: 0 |
| mov bx,ax | Internal cpu, ax register |
| mov bx,1 | Internal cpu, instruction buffer |
First to introduce next need to use terms such as under
SA represents the segment address
EA represents the offset
Segment Prefix
Command mov ax,[0], the address of the memory cell segment DS is the default, the register address given segment of the memory cell shown in the Instruction memory access unit where we can show, e.g.
mov ax,ds:[0]
mov ax,cs:[0]
mov ax,ss:[0]
mov ax,es:[0]
These instructions appear in the memory access unit, specifies the memory address for the segment display unit of the "ds",: cs ", " ss "," es ", in assembly to become segment prefix
[BX]
mov ax,[bx]
bx data stored as an offset address EA, SA is his default ds compared to the above (AX) = ((ds) * 16 + (bx))
[Si], [di]
Si and bx are functional and di similar registers, di and Si can not be divided into two 8-bit registers to use the same set of instructions to achieve the following three functions
mov bx,0
mov ax,[bx]
mov si,0
mov ax,[si]
mov bi,0
mov ax,[bi]
[dp]
mov ax,[dp]
Bx data stored as an offset address EA, SA is his default above was ss (ax) = ((ss) * 16 + (dp))
The following is an addressing mode in FIG cpu
