Writing AL, AH, or AX leaves other bytes unmodified in the full AX/EAX/RAX, for historical reasons. i.e. it has to merge a new AL into the full RAX, for example.

For example, in multiplication operation, one operand is stored in EAX or AX or AL register according to the size of the operand. BX is known as the base register, as it could be used in …

Jun 1, 2020 · In x86 assembly, al is the least significant byte of eax register, which is typically used to return values from function calls. The test al,al is a bitwise AND operation between al …

Nov 25, 2016 · The name "AL" still refers to bits 0-7 of the first letter-named register, "AH" to bits 8-15, and "AX" to bits 0-15; the name "EAX" now refers to all 32 bits of the register.

The sub-register AX allows us to access the lower 16 bits of EAX. And within AX are the two 8-bit sub-registers, AH and AL. But you may also have noticed that there’s a blank area to the lower …

For example, the least significant 2 bytes of EAX can be treated as a 16-bit register called AX. The least significant byte of AX can be used as a single 8-bit register called AL, while the most …

Oct 31, 2021 · What is the difference between the EAX AX AH and AL registers? ax is the 16-bit, “short” size register. It was added in 1979 with the 8086 CPU, but is used in DOS or BIOS …

Jul 17, 2015 · When EAX contains 1, the higher bytes contain 0 and AL 1 - that's the number representation in a 32 bits integer. When moving 8 in AL, EAX has still the three other bytes …

AL BL memory mode: all the segment registers are loaded with the same segment selector so that all memory references a program makes are to a single linear-address space.

ax is the 16-bit, "short" size register. It was added in 1979 with the 8086 CPU, but is used in DOS or BIOS code to this day. al and ah are the 8-bit, "char" size registers. al is the low 8 bits, ah is …