View 8086 INSTRUCTION SET Description.pdf from ELECTRICAL EC622 at Nirma University, Ahmedabad. 8086 INSTRUCTION SET: 1. Arithmetic Instructions 2. Bit Manipulation Instructions 3. Data Transfer Instruction Set of 8086 An instruction is a binary pattern designed inside a microprocessor to perform a specific function. The entire group of instructions that a microprocessor supports is called Instruction Set. 8086 has more than 20,000 instructions. 21-Nov-2010 ohmshankar.ece@act.edu.in 2 CBW − Used to fill the upper byte of the word with the copies of sign bit of the lower byte. CWD − Used to fill the upper word of the double word with the sign bit of the lower word. 3 Bit Manipulation Instructions. These instructions are used to perform operations where data bits are involved, i.e. operations like logical, shift, etc. Instruction. Description. MOV. Moves data from register to register, register to memory, memory to register, memory to accumulator, accumulator to memory, etc. LDS. Loads a word from the specified memory locations into specified register. It also loads a word from the next two memory locations into DS register. LES. The instruction set of 8086 can be divided into the following number of groups, namely: z. Data transfer instructions . z. Arithmetic instructions . z. Convert byte to word : CWD : Convert word to double word : Fig.14.4: Arithmetic instructions . The Instruction Set of 8086 229 12. Show the allowed operands for the instruction ADD, ADC and INC. The Arithmetic Instructions in 8086 allows you to subtract the ASCII codes for two decimal digits without masking off the "3" in the upper nibble of each digit. The AAS instruction can be .used after subtraction to get the current result in unpacked BCD form. DAS Instruction : Decimal Adjust After Subtraction. 8086 MICROPROCESSOR 1. If [CS]=348AH, [IP]=4214H, then the 20-bit physical address from which the code is accessed will [AX]=009BH, after the execution of CBW instruction the contents of AX will be (A) 009BH (B) FF9BH (C) 0000H (D) 9B9BH Answer: B . Detailed Solution: CBW converts the signed value in the AL register into an equivalent 16 You cannot use the CBW instruction for this, because the CBW instruction fills the upper byte with copies of the most significant bit of the lower byte. MUL BH Multiply AL with BH; result in AX MUL CX Multiply AX with CX; result high word in DX, low word in AX 8086 will generate a type 0 interrupt. All flags are undefined after a DIV The multiplication instructions provide you with your first taste of irregularity in the 8086's instruction set. To do so, use the cbw, cwd, cdq, or movsx instructions. If the H.O. byte or word does not already contain significant bits, then you must sign extend the value in the accumulator Arithmetic Instruction (8086) 8086 Microprocessor; by admin - October 15, 2020 October 23, 2020 0. Share on Facebook Share. Send email Mail. Print Print. CBW; IDIV div; OR use. AX=signed word; CWD; IDIV word; AAD: AAD: PF, SF,ZF, but AF, CF, OF are unaffected: Converts unpacked BCD to packed decimal. This instruction ASCII adjust before CBW No operands: Convert byte into word. Algorithm: if high bit of AL = 1 then: AH = 255 (0FFh) else When immediate is greater then 1, assembler generates several RCL xx, 1 instructions because 8086 has machine code only for this instruction (the same principle works for all other shift/rotate instructions). Algorithm: