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Original 8086/8088 instruction set In-struc-tion Meaning Notes Opcode AAA: ASCII adjust AL after addition: used with unpacked binary-coded decimal: 0x37: AAD: ASCII adjust AX before division: 8086/8088 datasheet documents only base 10 version of the AAD instruction (opcode 0xD5 0x0A), but any other base will work. Later Intel's documentation ...
x86 assembly language includes instructions for a stack-based floating-point unit (FPU). The FPU was an optional separate coprocessor for the 8086 through the 80386, it was an on-chip option for the 80486 series, and it is a standard feature in every Intel x86 CPU since the 80486, starting with the Pentium.
The Auxiliary Carry flag is set (to 1) if during an "add" operation there is a carry from the low nibble (lowest four bits) to the high nibble (upper four bits), or a borrow from the high nibble to the low nibble, in the low-order 8-bit portion, during a subtraction. Otherwise, if no such carry or borrow occurs, the flag is cleared or "reset ...
In assembly languages these instructions are represented by mnemonics such as ADD/SUB, ADC/SBC (ADD/SUB including carry), SHL/SHR , ROL/ROR (bit rotates), RCR/RCL (rotate through carry), and so on. [2] The use of the carry flag in this manner enables multi-word add, subtract, shift, and rotate operations.
Whereas the 8086 was a 16-bit microprocessor, it used the same microarchitecture as Intel's 8-bit microprocessors (8008, 8080, and 8085). This allowed assembly language programs written in 8-bit to seamlessly migrate. [7] New instructions and features — such as signed integers, base+offset addressing, and self-repeating operations — were added.
In computer programming, assembly language (alternatively assembler language [1] or symbolic machine code), [2] [3] [4] often referred to simply as assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence between the instructions in the language and the architecture's machine code instructions. [5]
An example, suppose we add 127 and 127 using 8-bit registers. 127+127 is 254, but using 8-bit arithmetic the result would be 1111 1110 binary, which is the two's complement encoding of −2, a negative number. A negative sum of positive operands (or vice versa) is an overflow.
The Intel 80186 and 80188 are essentially an upgraded 8086 or 8088 CPU, respectively, with on-chip peripherals added, and they have the same CPU registers as the 8086 and 8088 (in addition to interface registers for the peripherals). The 8086, 8088, 80186, and 80188 can use an optional floating-point coprocessor, the 8087.