General executin cycle of -> fetch decode and execute.
Three modes of operation -> real, protected and system management mode]
real mode is the 16 bit mode and the protected is the 32 bit mode with restrictions to the direct access to resources whereas real mode has no restrictions.
registers:
general purpose :
eax
ebx
ecx
edx
ebp
esp
esi
edi
the top 4 allow 8bit 16 bit and 32 bit access like eax has 16 bit ax further the lower and higher bytes are ah and al.
the lower four allow 16 and 32 only -- 16 bit -> si di bp sp
16 bit registers:
cs
ds
es
fs
gs
ss
other registers are flags stack-pointer program counter
One thing to note here is that these register may serve a specific purpose as defined eg eax for multiplication and division therefore also known as extended accumulator.
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