In this section we will see the addressing modes of Intel 8086 microprocessor.There are eight addressing modes in 8086 MPU. These modes are:Immediate Addressing ModeRegister Addressing ModeDirect Addressing ModeRegister Indirect Addressing ModeBased Addressing ModeIndexed Addressing ModeBased-Index Addressing ModeBased-Index with displacement addressing modeImmediate AddressingThe addressing mode in which the data operand is a part of the instruction itself is known as immediate addressing mode.MOV CX, 4929 H, ADD AX, 2387 H, MOV AL, FFH  Register AddressingIt means that the register is the source of an operand for an instruction.MOV CX, AX; copies the contents of the 16-bit AX register into; the ... Read More

The flag register is one of the special purpose register. The flag bits are changed to 0 or 1 depending upon the value of result after arithmetic or logical operations.8086 has 16-bit flag register, and there are 9 valid flag bits. The format of flag register is like below.BitsD15D14D13D12D11D10D9D8D7D6D5D4D3D2D1D0Flags    ODITSZ AC P CY We can divide the flag bits into two sections. The Status Flags, and the Control Flags.Status FlagsIn 8086 there are 6 different flags which are set or reset after 8-bit or 16-bit operations. These flags and their functions are listed below.Flag BitFunctionSAfter any operation if the MSB is 1, then it indicates ... Read More

The general purpose registers are used to store temporary data in the time of different operations in microprocessor. 8086 has eight general purpose registers. The description of these general purpose registersRegisterFunctionAXThis is the accumulator. It is 16-bit registers, but it is divided into two 8-bit registers. These registers are AH and AL. AX generally used for arithmetic or logical instructions, but it is not mandatory in 8086.BXBX is another register pair consisting of BH and BL. This register is used to store the offset values.CXCX is generally used as control register. It has two parts CH and CL. For different looping ... Read More

The Intel 8086 is 40 pin DIP Microprocessor. Here we will see the actual pin level diagram of 8086 MPU.8086 was the first 16-bit microprocessor available in 40-pin DIP (Dual Inline Package) chip. Let us now discuss in detail the pin configuration of a 8086 Microprocessor.This is the actual pin diagram of 8086 Microprocessor.Now let us see the Pin functions of the 8086 microprocessor.PinsFunctionAD15 – AD0These are 16 address/data bus. AD0-AD7 carries low order byte data and AD8AD15 carries higher order byte data. During the first clock cycle, it carries 16-bit address and after that it carries 16-bit data.A16 – ... Read More

In this program we will see how to perform addition by using ports to take data and send the result into the port.Problem StatementWrite 8085 Assembly language program for interfacing between 8085 and 8255. Here Port A and Port B are holding two values, take the numbers from port A and B, add them, and send the result at port C.DiscussionThe task is very simple. At first we have to setup the control word register of 8255 chip. After that we will take the input from port A and B, add the content, and send it to port C.The control ... Read More

A microprocessor is an integrated circuit which can function as a central processing unit (CPU) of a computer system or a microcontroller. It is constructed by integrating millions of transistors, diodes, and resistors on a single electronic chip.8085 and 8086 are two major types of microprocessors produced by Intel. Go through this article to find out the major differences between 8085 and 8086 microprocessors.What is 8085 Microprocessor?The 8085 microprocessor is an 8-bit microprocessor produced by Intel in 1976. The 8085 microprocessor has 8-bit long data bus, thus it can process 8-bit of data in a single cycle. The 8085 microprocessor ... Read More

In this program we will see how to transfer the switch values from one port to another using 8085 and 8255 chip.Problem Statement:Write 8085 Assembly language program for interfacing between 8085 and 8255. Here eight switches are connected at port A. Transfer the status of these switches into port B. In port B the LEDs are connected.Discussion:The task is very simple. At first we have to setup the control word register of 8255 chip. After that we will take the input from port A, and send it to port B.The control word register is looks like this. It is holding ... Read More

In this program, we will see how to check a 16-bit number is a palindrome or not.Problem StatementWrite the 8085 Assembly language program to check a 16-bit number is palindrome or not. The number is stored at location 8000H and 8001H.DiscussionA number is a palindrome if the number and its reversed sequence is the number itself. For example, 5225 is a palindrome, but ABCD is not a palindrome.In this problem, we are taking the number and store it into the HL pair. Then we are performing the reverse operation on L content. If the H and updated L value are ... Read More

In this program we will see how to lower and upper nibbles are masked in 8085.Problem StatementWrite 8085 Assembly language program to mask the upper and lower nibble of an 8-bit number. The number is stored at location 8000H. Lower and Upper nibbles will be stored at location 8001H and 8002H.DiscussionThe masking is basically ANDing two numbers. When we want to mask the upper nibble of an 8-bit number say 2D (0010 1101), then we will AND with 0F (0000 1111), so we will get 0D (0000 1101). By masking with F0 (1111 0000), the result will be 20 (0010 ... Read More

In this program we will see how to reverse the digits of a 16-bit number using 8085.Problem StatementWrite 8085 Assembly language program to reverse a 16-bit number stored at location 8000H-8001H. Also, store the result at 8050H – 8051H.DiscussionHere the task is too simple. There are some rotating instructions in 8085. The RRC, RLC are used to rotate the Accumulator content to the right and left respectively without carry. We can use either RRC or RLC to perform this task. In the final result each digit of the H and L are reversed, and also the H and L values ... Read More