geocar, you're wrong, mkup is right. I've checked a few disassembled https://onlinedisassembler.com/odaweb/z1mMaYSk/0 https://onlinedisassembler.com/odaweb/z1

geocar, you're wrong, mkup is right. I've checked a few disassembled https://onlinedisassembler.com/odaweb/z1mMaYSk/0 https://onlinedisassembler.com/odaweb/z1mMaYSk/0 locations of his binary file (which is identical to the binary I can produce with the nasm):   :0000001f 6683c402 add $0x2,%esp     :00000025 6655 push %ebp   :00000027 6689e5 mov %esp,%ebp There's a 66h "Operand-size override" prefix present in the binaries which is not needed in the 16-bit code. The proper instructions would be "push bp" etc.