ABSTRACT
This chapter discusses arithmetic operations on the Intel central processors, including operations on ASCII decimal and binary code decimal numbers. All 80x86 CPUs are equipped with a special register that reflects the current status of the microprocessor. This register has been called the status word, the Status register, the Flags register, and the E flags register. The status register contains bits that are meaningful during the execution of logic and arithmetic operations. The 80286 CPU introduced several new control flags. The Status register was expanded to 32 bits in the 80386 CPU and renamed the E flags register. However, the flags used for arithmetic and logical operations, usually called the status flags, remained unchanged. The AND opcode performs a logical AND of the two operands. This action determines that a bit in the result is set if and only if the corresponding bits are set in both operands.
