Adding these two numbers give 15E resulting into overflow. The JAE/JNB/JNC instructions check Carry flag (CF). If the two numbers are equal, zero flag (ZF) will be equal to 1. The JNS instruction is a jump if the result of the previous instruction is not a signed number or positive whereas JS instruction is a jump if the previous instruction is a signed value or negative. << The term byte was coined by Werner Buchholz in June 1956, during the early design phase for the IBM Stretch computer, which had addressing to the bit and variable field length (VFL) instructions with a byte size encoded in the instruction. In the far jumps, the program counter jumps to the memory location which lies outside the current code segment whereas in near jumps, the IP points to the memory address inside the current code segment and that is why the CS register remains unchanged in near jumps. There are two types of jumps namely Far and Near. The JO instruction checks the overflow flag. If it is 1, the program counter jumps to L1 which will print the message “Equal numbers” on the emulator screen. S. Dandamudi Arithmetic: Page 11 Status Flags (cont’d) ∗Carry flag is not set by inc and dec instructions » The carry flag is not set in the following examples mov AL,0FFH mov AX,0 inc AL dec AX ∗Related instructions jc jump if carry (jump if CF = 1) jnc jump if no carry (jump if CF = 0) The conditional jumps are also near jumps. 5. which are of these examples of Intel 8086 opcodes: a. MOV b. If CF is 1, then the instructions after label address L2 will undergo execution. The code below explains the behavior of JO instruction. �s9ah��� �c�q��j7���l�h.��$21T �T���8��$F���(j8����mF6�)���*�Tc� P1� P�-�E�ףcap�86�G1��0- ��Q�{_�F Notify me of follow-up comments by email. It checks one or more flag conditions and transfers the control to a new memory location. History. When we add two numbers the destination address must always be. This set of 8051 Micro-controller Multiple Choice Questions & Answers (MCQs) focuses on “Arithmetic and Logic Instructions”. These instructions are executed after some other instructions which affects the content of flag registers. The unconditional branches are those in which the program counter jumps to the label address provided within the instruction. If AH is greater or equal to CH data, then the program counter will jump to the L1 label. %���� The flag conditions are checked depending upon the instruction, if they are true the program control is transferred to the memory address pointed by the IP register. 1. The code in example 5 adds two numbers and check if the result is a positive number or not. �D(�� �y�3��R�"0 �#! It adds two numbers and check the overflow. ADD c. SUB d. All of these 6. Moreover, if any one of them is 0 and other is 1, then this instruction will have no effect of program execution. Table below shows the mnemonics of all the conditional branches instructions. On the other hand, the conditional branches are those instructions whose execution is based on some condition. If the result is too large to fit in the destination register, then it will set overflow bit to 1. �7��� �R�B[��Q20��t���@&Z�D � �8�\�@�2㷀P(^a@��>�ZfX0�6�9��%�����ᡦ���0gz�x�! The JA instruction will check if CF is 0. Copyright © 2013-2021 /Length 2101 If the zero flag is 0, then the program counter will jump to the next instruction which is JB L2. Now after the execution of JAE instruction, the program counter will not jump to L1 instead it would execute the next instruction after JAE instruction. It is sign-extended to 16-bits and added to the contents of IP register. In this article, we will discuss branch instructions which are supported by the 8086 microprocessor. 23. /Filter /LZWDecode This assembly example checks the parity and shows it on emulator screen. For example: Suppose AH=C9H and BH=7AH. If the number is positive, the program stops running otherwise the program will jump to the NEXT label in which the result is multiplied with -1 to convert it into a positive number. 2 0 obj If AH is less than the CH, then it will borrow carry thus setting CF to 1. Let’s discuss these instructions in detail through examples. The code below compares two numbers and print if number 1 is equal, greater or less than number 2. D{*�jQ�8�4@[.��a���wM�b JE instruction checks ZF. Intel iAPX 8086/8088 & 80186/286, Zilog Z 8001/8002, Motorola 68000 and National semiconductor NS 16000. If it is 1, the control is transferred to label address. The target address must be within the -128 to +127 bytes of IP. If it is 0, jump to the target address. Microcontrollerslab.com All Rights Reserved, List of 8086 Conditional Branch Instructions, 8086 Microprocessor Assembly Comparison Example, 8086 JO Branch Instruction Assembly Example, 8086 JNP Branch Instruction Assembly Example, 8086 JNS Branch Instruction Assembly Example, Install ESP32 Filesystem Uploader in Arduino IDE – SPIFFS, MPU6050 with Arduino – Display values on SSD1306 OLED, MicroPython: ESP32 Deep Sleep Mode and Wake Up Sources, Getting Epoch/Unix time with ESP8266 NodeMCU through NTP server using Arduino IDE, Getting Epoch/Unix time with ESP32 through NTP server using Arduino IDE, Jump if Above or Equal/ Jump if Not Below/Jump if No Carry, Jump if Below/ Jump if Not Above or Equal, Jump if Below or Equal/ Jump if Not Above, Jump if Greater/Jump if Not Less Than or Equal, Jump if Greater or Equal/Jump if Not Less Than, Jump if Less Than/Jump if Not Greater Than or Equal, Jump if Less than or Equal/Jump if Not Greater. ��m���[�N*�Φ�7���z�SK[�׶�� There is another instruction that is used to check whether the result is positive or negative and jumps to the label address depending upon the sign of the result. If it is 1, the control will be transferred to NEXT label which will then display message of “OVERFLOW” on the emulator screen. If the condition is not satisfied, then the program continues in a sequential manner. @�r���6by������3���qzÓj����E]oa�p�;�iCY���f ���B��[NF����e:Lb�h�P�`ˆ��� �Hj� �7c��:�o�P����R.��R,��lJ%����������C��,@Sҙ�cD�����(��p�\� As OF = 1, therefore after JO instruction, the instructions after label NEXT are executed. �7X��7�j⸂��^����J#y"��fPA�Y�s'��#���K�xe "R2**����� #+�Wh�DhP�IF)�&�����I(�� Ȉ��f,���F\�C�//�f��Dt��,�0a�Q��nv"�xf����@LJ4��۞ ��!B�f JA/JNBE will check the CF and ZF flags. The JB or JBNE instructions check whether CF flag is 1 or not. The syntax of these instructions is: It is a 2-byte instruction consisting of 1-Byte Opcode and 1-byte Label. The code below compares two numbers and print if number 1 is equal, greater or less than number 2. The JNP instruction checks the parity flag. stream As it generates carry, therefore, CF becomes equal to 1. In this example, the two numbers are 0C9H and 95H. If parity is odd or PF=0, the program counter will jump to the label address. These instructions are executed after some other instructions which affects the content of flag registers. �(h5��:�L�)�q�u�A��g�� 8�[��i�;���^ Enter your email address to subscribe to this blog and receive notifications of new posts by email. �(*���H�f��U��*J*�h�=���-\o��0۱��~������v�⏳�9�D+�Wpbg���d��uSb���%=9��9ɮ���P-ߠ���=26m���),�T����J�|j��{UK8�DN��7ްd����)èt �5n8���H��;%(���Vr3�(���5a�`/$�P�8i�:�E�]� �u�6�@��3�M�ǔ�R� Let’s discuss these instructions in detail through examples. C& �NDC��d{��Q2I�x��L���H�y(�P�(�>-�痑�Mh,3�踂�T��%"JFIG/����n7,(� b\ގ��R̩N�U�PZ.x �P�4��M`��)�X�hAr�#I��$f. a) some immediate data b) any register c) accumulator d) memory View Answer There are two types of branches or jumps namely conditional and unconditional branches. If the OF=0, then the sum is stored in the variable “RESULT” which is stored in memory. If both are 0, then the IP will jump to the target address. Even if you don’t use this instruction in the code given below, it will not affect the program execution as if the first two conditions are not satisfied, then it means the number 1 is greater than number 2. Now replace ADD instruction with CMP instruction. When OF is 0, JNO instruction will jump the program counter to the instruction whose label address is provided within the JNO instruction. We will also discuss assembly language programming examples of conditional branch instructions. Also, if both CF and ZF are equal to 1, then the program will continue to execute sequentially. Label value is between 00 and FF. The JNO instruction is opposite to JO instruction. >> This code is implemented using three conditional branches which are JE, JB and JA. �Z����P���iH�#��>�\�0r � �6�!�`� �"��Rڒ��ƫ��h�6�B���+˴ȵ �h/t�9�9�a�����sS�,B�93��P�R�솪����,�'�r��գ���H2��K;�-+X竎�`*����ld���P*?����� �2������S/ے[�2[��� �L������.۰D�6�#HY{?��dw�P$̡�� ?���2B���[ C! Describe briefly Intel 80486 and Pentium-1 processors . The Compare instruction subtracts the content of CH from AH. %PDF-1.1 8086 Microprocessor Assembly Comparison Example . The JP instruction checks if parity is even or PF=1. _____specify where to get the source and destination operands for the operation specified by the _____: a. Operand fields and opcode b. Opcode and operand c. Source and destination d. CPU and memory 7. The first instruction adds C9 and 7AH and gives 143. The Intel 8080 ("eighty-eighty") is the second 8-bit microprocessor designed and manufactured by Intel.It first appeared in April 1974 and is an extended and enhanced variant of the earlier 8008 design, although without binary compatibility.

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