The first column in the above listing is offset of the listed instruction in the output file. Next column is the opcode into which our instruction was translated. In this case this opcode is B8. Whenever we move a constant into AX register the opcode B8 will be used. After it 0500 is appended which is the immediate operand to this instruction. An immediate operand is an operand which is placed directly inside the instruction. Now as the AX register is a word sized register, and one hexadecimal digit takes 4 bits so 4 hexadecimal digits make one word or two bytes. Which of the two bytes should be placed first in the instruction, the least significant or the most significant? Similarly for 32bit numbers either the order can be most significant, less significant, lesser significant, and least significant called the big-endian order used by Motorola and some other companies or it can be least significant, more significant, more significant, and most significant called the little-endian order and is used by Intel. The big-endian have the argument that it is more natural to read and comprehend while the little-endian have the argument that this scheme places the less significant value at a lesser address and more significant value at a higher address.

Because of this the constant 5 in our instruction was converted into 0500 with the least significant byte of 05 first and the most significant byte of 00 afterwards. When read as a word it is 0005 but when written in memory it will become 0500. As the first instruction is three bytes long, the listing file shows that the offset of the next instruction in the file is 3. The opcode BB is for moving a constant into the BX register, and the operand 0A00 is the number 10 in little-endian byte order. Similarly the offsets and opcodes of the remaining instructions are shown in order. The last instruction is placed at offset 0x10 or 16 in decimal. The size of the last instruction is two bytes, so the size of the complete COM file becomes 18 bytes. This can be verified from the directory listing, using the DIR command, that the COM file produced is exactly 18 bytes long.

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