8085 Microprocessor Course – Learn from scratch

Course content

What is the difference between microcontrollers and microprocessors?

An age-old question broken down into a simple conceptual explanation. The difference between microcontrollers and microprocessors is easy to remember with this explanation.

8085 Pins – Understanding the 8085’s pin diagram

The 8085 has 40 pins. Understanding the function of each pin will give you a brief idea about the capabilities of the microprocessor.

Understanding the 8085 Architecture

The architecture of any processor is the key to understanding everything about it. Its purpose, its capacity, and power, everything can be understood from a peek at the innards of the chip. Studying the 8085’s internal architecture will set you up towards understanding any processor in a jiffy.

Addressing Modes in 8085 Microprocessor

All processors and controllers can access data stored in the memory using instructions or commands. However, the method in which they access this data varies on the addressing modes that they are capable of using. So, in short, data access has many types, known as addressing modes. Let’s take a look at the addressing modes available in 8085.

Data Transfer Instructions in 8085 – With example codes

We begin our foray into the instruction set of the 8085 microprocessor with the data transfer instructions. These instructions, as their classification suggests, are used to move around data within, from, or into the microprocessor.

Arithmetic Instructions in 8085 – With example codes

Next up, we’ll take a look at the arithmetic instructions available to us in 8085. Keep an eye out for the subtraction instructions. The 2’s complement aspect can make them seem confusing at first.

Logical Instructions in 8085 – With example codes

The third category of the instruction set is the bunch of instructions that are responsible for implementing logic and helping the ALU perform logical operations.

Buses in 8085 – Demultiplexing and Generating Control Signals

The buses of any processor are the network through which all communication inside an embedded system is done. Both, internal as well as external. Without the buses, it’s like having a Ferrari with no wheels. The bus structure of a processor can tell you a lot about its design and how it can be interfaced with the outside world. For the 8085, we have a few unique processes that we need to run to use its buses. First, we will understand the role of all the buses, and then we will understand the processes that need to be done to use them. Though these processes might seem convoluted right now, rest assured, it has all been done in the interest of optimizing the processor for best usage.

Timing diagrams and Machine cycles – Learn with 8085 instructions

A good embedded systems developer is expected to be in tune with the effect their code is having on the internal circuitry of the device they are programming. This skill develops over time and helps you optimize your code for efficiency and quickly debug it in the event of some nasty bugs. Here’s one of the concepts that zeros in on how instructions execute on a micro-level. Learning how timing diagrams work will come in handy as we progress to much more complex topics like instruction parallelism, multi-threading, and RTOS.

External memory interfacing in 8085: RAM and ROM

The 8085 microprocessor doesn’t have any built-in memory. Thus, to use it in any significant project we need to interface external memory chips to it. This is a complete guide on how you would go about doing that. There’s an example problem to help you get a more application-based explanation too.

Stack, Stack pointer and Subroutines in 8085 – With coding examples

The stack is an important data structure in embedded systems as it allows us to increase our code efficiency by implementing subroutines. Let’s study everything we need to know to start using them.

Interrupt Structure of the 8085

Almost every modern processor has a system to handle interrupts. Let’s take an in-depth look at the entire process of how interrupts work in the 8085 processor. Interrupts classification, their types, and internal circuitry.

Data Transfer Techniques in 8085

A microprocessor deals with a lot of data passing through it. However, not all recipients and senders of this data are alike. They might have many differences in terms of how they send or receive data. Hence, we need different data transfer mechanisms. Let’s take a look at all the different ways in which the 8085 transfers data between peripherals and itself.

Difference between Memory mapped I/O and I/O mapped I/O

Interfacing I/O devices with a processor is an integral part of any embedded system. With the 8085, there are two methods to interface I/O devices; I/O mapped I/O and memory-mapped I/O. Both of these methods have their perks and snags. This is an important concept. So pay attention and understand the difference between the two methods. We’ll revisit this in the ARM Cortex M course.

8255 Programmable Peripheral Interface – In-depth simple explanation

The 8255 is/was a very common IC primarily used to increase the number of I/O pins that a microprocessor could address. However, the 8255 is extremely powerful and does a lot more than simple I/O data transfers. Here’s a simplified and in-depth explanation of the 8255 programmable peripheral interface. This is your one stop guide to completely understand its working.

Interfacing of 8085 with 8255 Programmable Peripheral Interface

Now that we are familiar with the working of the 8255, let’s interface it with the 8085.

8085 Microprocessor MCQ | Quiz | Interview Questions

This 8085 quiz has been crafted to test skills in a wide range of concepts that we have covered in this free course. Competitive exam takers will find the detailed solutions helpful. Clearing this quiz will unlock the final certification test. For detailed performance analysis, please ensure that you are logged in before attempting the quiz.

More details

New posts are still being added to this course. 

What will you learn in this course?

  • Basic concepts of microprocessors and their essential functionalities.
  • Ability to comprehend microprocessor architecture.
  • Ability to read instruction set documentation and understand its implementation and execution.
  • Identify common peripherals.
  • Understand different methods of interfacing I/O peripherals.
  • Understand and design timing diagrams for various instructions.

Are there any software or hardware requirements for this course?

Yes. We will be using an online simulator (Sim8085) for simulating our assembly language programs. It is a very straightforward and simple simulator that allows us to check for flag status, changes in memory locations, and register contents. Using this simulator we will understand how assembly language instructions affect the internal components of the 8085 microprocessor.

Generally, we would advise you to get a physical 8085 learning kit (like this one). However, looking at the bigger picture in terms of our embedded systems track, we would advise that you save your money. Instead, learn the basics of microprocessors in this course and invest in a good development kit when you begin the course on the ARM Cortex M processor.

What is the target of this course?

This course is part of our tracks in Embedded Systems, IoT, and Robotics. We have designed these tracks and their constituent courses (like this one) to equip learners with the basic requirements of entry-level jobs or internships in the respective fields. Head over to the pages of any of these tracks to get more information.

Are there any pre-requisites for this course?

How many quizzes are there in this course?


I would like to suggest some topics to be covered, how can I do that?

You can visit the contact page linked in the footer of this webpage. Just select “Suggest Topics” from the subject dropdown menu of the form, mention the course and why you think your suggestion makes sense to be part of the curriculum.