microprocessor

Opcode fetch machine cycle in 8085

The Opcode fetch machine cycle is the first step in the execution of any instruction. In this cycle, the microprocessor reads the opcode of an instruction from the memory. The control and status signals for this machine cycle are IO/M’ = 0, S0 =1, and S1 = 1. This differentiates it from the memory read […]

8085 program to swap two 8-bit numbers

In this post, we will write one 8085 program to swap two 8-bit numbers. We will take a problem statement first and then find out the solution methods, algorithm and then will write the 8085 assembly programs to solve the problem. Program Statement: Swap the contents of memory locations 2000H and 4000H using 8085 assembly […]

Memory Mapped IO and IO Mapped IO in 8085 microprocessor

In this post, we will study Memory-mapped I/O and Peripheral-mapped I/O (i.e., IO Mapped IO) scheme, and find out differentiating features of these two schemes. There are generally two addressing schemes for I/O devices in a 8085 microprocessor based system. Memory-mapped I/O and I/O mapped I/O or Peripheral-mapped I/O. Memory-mapped I/O scheme – features Each […]

DAA Instruction in 8085 for BCD addition

In this post, we will study how to use DAA Instruction in 8085 for BCD addition. DAA is the 8085 instruction that supports BCD addition. The addition of BCD is done like binary addition, using the ADD instruction. DAA is used to convert the result of the binary sum (Available in the Accumulator) into a […]

Interfacing of 8255 PPI with 8085 microprocessor

PPI 8255 is a general-purpose programmable I/O device designed to interface the CPU with its outside world such as ADC, DAC, keyboard, etc. We can program it according to the given condition. It can be used with almost any microprocessor. Here in this post, we will discuss the interfacing of 8255 PPI with 8085 microprocessor […]

RLC and RAL instructions in 8085

Instructions RLC and RAL are basically two logical instructions available in 8085 instruction set, to rotate the bits of the accumulator one position to the left. Now to understand the difference between RLC and RAL instructions, their functions are explained with diagrams first and then with some numerical examples. Difference between RLC and RAL instructions […]

Timing diagram of INX H in 8085

In 8085 Instruction set, INX H stands for “INcrement eXtended register” and H stands for H-L register pair. This instruction will be used to add 1 to the present content of the H-L pair. And thus the result of the incremented content will remain stored in H-L pair itself. Though it is an arithmetic instruction […]

Addition of two 8 bit numbers using 8051

In this post, we will see how to perform the addition of two 8 bit numbers using 8051 instruction set. ALGORITHM: Addition of two 8 bit numbers using 8051 Clear C – register for Carry Get the data immediately . Add the two data Store the result in memory pointed by DPTR Programming using 8051 […]

Interfacing ADC with 8085 microprocessor (program)

In this post, we will write a program for interfacing ADC with 8085. This 8085 assembly language program will initiate ADC (Analog to Digital Converter) and store the digital data in memory. Interfacing ADC with 8085 using 8255 We have to write a program with 8085 assembly language to Initiate ADC and store the digital […]

Addition of two 16-bit numbers: 8085 programming

In this post, we will write programs in 8085 Assembly language for the addition of two 16-bit numbers. In program 1, eight bit addition instructions are used (ADD and ADC) and addition is performed in two steps. First lower byte addition using ADD instruction and then higher byte addition using ADC instruction. In program 2, […]

Packing & Unpacking of BCD numbers: 8085 programming

In this post, we will write programs in 8085 Assembly Language for Packing and unpacking of BCD numbers. Packing of BCD numbers: 8085 programming Problem statement: Pack the two unpacked 4-bit single digit BCD numbers stored in memory locations C200H and C201H and store result in memory location C300H. Assume the least significant digit is […]

The Architecture of 8085 and 8086 – Questions & answers

In this post, we will answer a bunch of selected questions on the architecture of 8085 and 8086 microprocessors. After reading this article students will get an overall idea about the question pattern and the answer tips. This will also help the students with the self-study on 8085 and 8086 architecture. What is meant by […]

Memory organization in 8086 microprocessor

After studying this article the readers will be able to understand the physical memory organization, 20-bit address generation technique, the need for memory segmentation, etc. in 8086 microprocessor. Frequently asked questions (FAQs) and their detailed answers in this post are going to help the readers to prepare for the Semester exam, GATE exam, and the […]

Interrupts in 8086 Microprocessor

In this post, we will build our concepts on the Interrupts in 8086 Microprocessor with the help of a set of questions and answers. What is the function of an interrupt in a microprocessor? An Interrupt is a condition that halts the microprocessor temporarily so that the microprocessor can work on a different task and […]

Is assembly language the same thing as machine language?

While the two terms, assembly language and machine language, are often used interchangeably, assembly language is a more “user-friendly” interpretation of machine language. Machine language is the collection of patterns of bits recognized by a central processing unit (CPU) as instructions. Each particular CPU design has its own machine language. The machine language of the […]

External memory interfacing in 8085: RAM and ROM

In one of our previous posts, we have discussed how the 8085 reads from and writes into memory. But we know that, unlike microcontrollers that have a certain amount of built-in memory, microprocessors do not have their own memory except for a few registers. So we need to attach external memory chips. Now the question […]

HEX to ASCII conversion program in 8085 – PhysicsTeacher.in

In this post, we will see how to convert a given Hexadecimal number into its equivalent ASCII number using the 8085 microprocessor instruction set. (HEX to ASCII conversion) Algorithm for HEX to ASCII Conversion with 8085 microprocessor Load the given data in A register and move to B register Mask the upper nibble of the […]

HEX to BCD conversion program in 8085 – PhysicsTeacher.in

In this post, we will see how to convert a given Hexadecimal number into its equivalent BCD number using the 8085 microprocessor instruction set. (HEX to BCD conversion) Algorithm for HEX to BCD Conversion with 8085 microprocessor 1) Initialize memory pointer to 4150 H2) Get the Hexadecimal number in C – register3) Perform repeated addition […]

BCD to HEX Conversion program in 8085 – PhysicsTeacher.in

In this post, we will see how To convert two-digit packed BCD numbers in memory to the equivalent HEX number using the 8085 microprocessor program or instruction set. Algorithm for BCD to HEX Conversion with 8085 microprocessor 1) Initialize memory pointer to 4150 H2) Get the Most Significant Digit (MSD)3) Multiply the MSD by ten […]

Arithmetic Instructions in 8085 – PhysicsTeacher.in

In this post, we will discuss the Arithmetic Instructions in the 8085 Microprocessor required for arithmetic operations. Arithmetic operations supported by the 8085 Microprocessor are addition, subtraction, and their variants. The arithmetic instructions in the 8085 microprocessor are described here in detail. Addition (ADD, ADI) With the Addition instruction, the following 3 operations can be […]

8085 microprocessor program for 1’s & 2’s complement of a number

In this post, we will write down programs in assembly language for the 8085 microprocessor to complement a number (1’s complement and 2’s complement). Here are the problem statements and the required programs, input data, and results. 1’s complement – problem statement for the 8085 microprocessor Problem statement: Write down an assembly language program to […]

Addressing modes in 8085 microprocessor

In this post, we will discuss different addressing modes in the 8085 microprocessor with examples. Addressing modes in instructions Each instruction indicates an operation to be performed on certain data. The process of specifying the data to be operated on (operand) by the instruction is known as ‘addressing’. The various formats for specifying operands are […]

Instruction Set and Types of instruction in 8085

In this post, we will discuss the Instruction set and Types of instruction in the 8085 microprocessor through a set of questions and answers. What is an instruction? An instruction is a bit pattern that is decoded inside a microprocessor to perform a specific task or function on a given data. What is meant by […]

Demultiplexing of address and data bus in 8085

In this post, we will see how Demultiplexing of multiplexed address and data bus AD7-AD0 in 8085 is done. The 8085 uses a multiplexed data bus and address bus. This means the Lower address bus (A7 – A0) and the data bus (D7 – D0) are available on the same pins AD7 – AD0. Multiplexing […]

Instruction Cycle and Machine Cycle in 8085 Microprocessor

In this post, we will discuss Instruction Cycle and Machine Cycle in the 8085 Microprocessor. In this process, we will go through questions and answers related to the Fetch Cycle, Instruction Cycle, Machine Cycle & T-state of 8085. We know that the microprocessor is called a sequential machine because it performs the jobs in a […]

MCQs on AVR microcontroller, 8255, 8051 – NPTEL assignment

This assignment (MCQs on AVR microcontroller, 8255, 8051 – NPTEL assignment) contains 14 MCQs spanned across 3 pages. Links to other pages of this assignment are available at the bottom of each page of this series. AVR microcontroller, 8255, 8051 – MCQs 1 ) Which of the following representations related to the AVR microcontrollers is […]

MCQs on 8086 microprocessor – NPTEL assignment

This assignment (MCQs on 8086 microprocessor – NPTEL assignment) contains 15 MCQs spanned across 3 pages. Links to other pages of this assignment are available at the bottom of each page of this series. 8086 microprocessor based MCQs 1 ) Which of the following statement(s) is/are correct? a) If MN/MX’ is low, 8086 cannot be […]

Architecture of 8085 microprocessor

The 8085 is an 8-bit processor since its data length and data bus width are 8-bits. It has an addressing capability of 16 bits, that is, it can address 216=64 KB of memory. The 8085 processor is generally available as a 40-pin IC package and uses+5V for power. It can run at a maximum frequency […]

Different Signals in 8085 & their significance

In this post, we will study Different Signals in 8085 & their significance. Here, we have answered a set of frequently asked questions to study this. Describe in brief the function of timing and control circuitry of 8085 microprocessor The timing and control unit section is a part of the CPU and generates timing and […]

Special-purpose registers in 8085 microprocessor

In this post, we will study the Special-purpose registers in the 8085 microprocessor with the help of a bunch of Frequently Asked Questions. Describe the special-purpose registers in 8085 Special-purpose Registers are dedicated to a specific function. The accumulator, flag register, program counter (PC), and stack pointer (SP) constitute the special purpose registers in the […]

General purpose registers of 8085 microprocessor

This post covers a set of FAQs on general-purpose registers of 8085 microprocessor. Describe the general-purpose registers of 8085 microprocessor We know that the registers are all storage areas inside the microprocessor and are used for different purposes. General-purpose Registers are used to store only the data that is being used by the program under […]

How to Interface a RAM chip with 8085 microprocessor

In this post, we have discussed the interfacing of a 1 KB RAM chip with the 8085 microprocessor. We have also discussed the Memory mapping of the RAM chip. Steps followed by the 8085 microprocessor to read the content of a memory location in the RAM chip are also discussed. We know that the programs […]

8085 Executing the program and checking result

Executing the program and checking results in the 8085 Microprocessor – In this post, we have discussed how the 8085 microprocessor executes one program and how to check results in 8085. This will also help to understand how a microprocessor works. Executing the program and checking result in 8085 Microprocessor A microprocessor is a sequential […]

Difference between microprocessor and microcontroller

To understand the difference between microprocessor and microcontroller we need to understand what microcomputer system and microcontroller (i.e. single-chip microcomputer system) are. To make a complete microcomputer system, only a microprocessor is not sufficient. It is necessary to add other peripherals such as read-only memory(ROM), read/write memory(RAM), decoders, drivers, number of input/output devices to make […]

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