Is It Save To Remove:

that's similar to shift from 16 to 32 bits

when the cpu is reset it start exec from 0xFFFF (it bit real mode)

then if a 32 bit OS loads it swiches the cpu to 32 bit protected mode (after getting cotrol transfrred by BIOS)

for 64 bit similarlt it initiates 64 bit protected mode.

for 64 bit processor it has all the register for 16,32 and 64 bit oses

for 16 bit -- AX,BX,CX DX, SI,DI,IP,etc

for 32 bit -- EAX, EBX, ECX, EIP etc

for 64 bit -- RAX,RBX,RCX etc

|<---------------------------64 bit------------------->|

|<------32 bit---------->|

|<---8 bit -->|

|--------------------------------------------------------|

|--------------------------------------------------------|

|<--AX----->|

|<------ EAX------------>|

|<-----------------RAX------------------------------->|

the same register appear differently for differet oses