Working of 8085-based Single board microcomputer
Last Updated :
12 May, 2023
Prerequisites - Pin diagram of 8085 microprocessor, Bus organization of 8085 microprocessor Single board microcomputers are the system which have a program called Key Monitor or Key Executive permanently stored in memory. This program is stored either in EPROM or in ROM, beginning at the memory location 0000H. Hardware is the skeleton of the computer and software is its life. The software (programs) makes the computer live; without it the hardware is a dead piece of semiconductor material. When the power is turned on, the monitor program comes alive. Initially, the program counter has a random address. When the system is reset, the program counter in the 8085 is cleared and it holds the address 0000H. The trainer system includes a "power on" reset circuit, which reset the system and clears the program counter when system is turned on. The MPU places the address 0000H on the address bus. The instruction code stored in location 0000H is fetched and executed, and the execution continues according to the instructions in the monitor program. The primary functions of monitor program are as follows:
- Reading the Hex keyboard and checking for a key closure. Continuing to check the keyboard until a key is pressed.
- Displaying the Hex equivalent of the key pressed at the output port, such as the seven segment LEDs.
- Identifying the key pressed and storing its binary equivalent in memory, if necessary.
- Transferring the program execution sequence to the user program when the Execute key is pressed.
The programmer enters a program in R/W memory in sequential memory locations by using the data keys (0 to F) and the function key called Enter. When the system is reset, the program counter is cleared, and the monitor program begins to check a key closure again. By using the keyboard, the programmer enters the first memory address where the user program is stored in R/W memory and directs the MPU to execute the program by pressing the Run key. The MPU fetches, decodes and executes one instruction code at a time and continues to do so until it fetches the Halt instruction. The Key monitor program is a critical element in entering, storing and executing a program. Until the Execute key is pushed, the monitor program in the EPROM (or ROM) directs all the operations of the MPU. After the Execute key is pushed, the user program directs the MPU to perform the functions written in the program.
Advantages:
Cost-effective: The 8085-based single board microcomputer is a cost-effective solution for many applications, as it provides a complete system on a single board, eliminating the need for additional hardware.
Easy to use: The 8085 microprocessor is a well-established architecture that is easy to use and program, making it suitable for a wide range of applications.
Availability of software tools: A wide range of software tools and compilers are available for the 8085 microprocessor, which makes it easier to develop and debug applications.
Expandability: The single board microcomputer can be expanded with additional peripherals such as I/O devices, memory, and communication interfaces, making it suitable for a variety of applications.
Low power consumption: The 8085 microprocessor is a low power device, which makes it suitable for battery-powered applications.
Disadvantages:
Limited processing power: The 8085 microprocessor has limited processing power compared to more modern microprocessors, which can limit the performance of the system.
Limited memory: The 8085 microprocessor has a limited address space, which can limit the amount of memory that can be used in the system.
Limited peripherals: The 8085 microprocessor has limited built-in peripherals, which can limit the functionality of the system.
Limited connectivity: The 8085 microprocessor has limited connectivity options, which can limit the ability to interface with external devices.
Limited availability: The 8085 microprocessor is an older architecture, which may limit its availability and support in the future.
Features:
8-bit microprocessor: The 8085 microprocessor is an 8-bit processor, which means it can handle 8 bits of data at a time. This limits its processing power compared to newer processors, but it is still capable of running a wide range of software and applications.
Memory: The microcomputer typically includes memory, which is used to store the program instructions and data being processed by the microprocessor. The memory may include both read-only memory (ROM) and random access memory (RAM).
I/O ports: The microcomputer typically includes a variety of I/O ports, such as serial and parallel ports, which are used to interface with other devices.
Clock: The microprocessor requires a clock signal to synchronize its operations, and the microcomputer typically includes a clock generator to generate the necessary clock signal.
Similar Reads
Pin diagram of 8051 Microcontroller Introduction : The 8051 microcontroller is a popular 8-bit microcontroller widely used in embedded systems. It is a single-chip microcontroller with a Harvard architecture that includes a CPU, RAM, ROM, and several peripherals. The 8051 microcontroller has a 40-pin dual in-line package (DIP) that pr
9 min read
Pin diagram of 8085 microprocessor The 8085 microprocessor is a popular 8-bit microprocessor developed by Intel. It has 40 pins, each with a specific function for interfacing with memory, input/output devices, and other components.Pin diagram of 8085 microprocessor is shown below: Key Pin Descriptions1. Address Bus and Data BusAddres
5 min read
ALE Pin in 8085 Microprocessor This pin of the 8085 microprocessor, ALE, is one of the most important pins used in interfacing with external memory devices. During any machine cycle, while interfacing with an external memory using the 8085 microprocessor, the ALE pin latches the lower-order address bits, A0-A7.During the beginnin
14 min read
Bus organization of 8085 microprocessor Introduction : The bus organization of the 8085 microprocessor is the way in which the microprocessor communicates with other devices in a computer system. The 8085 microprocessor has a 16-bit address bus, an 8-bit data bus, and various control signals that are used to manage data transfer and other
9 min read
Pin diagram of 8086 microprocessor The 8086 chip, presented by Intel in 1978, is a critical part in the development of processing innovation. Its pin outline is a basic part of figuring out its design and usefulness. The pin chart gives a visual portrayal of the chip's outer associations and their individual capabilities, including p
8 min read
Introduction of Microcomputer System Introduction of Microcomputer System Microcomputer systems are small and inexpensive computers that are widely used in various applications. The 8085 microprocessor is an example of a Microcomputer System. A microprocessor system contains two types of memory that are EPROM and R/WM, Input and Output
4 min read
Serial I/O Lines in 8085 Microprocessor Introduction : The 8085 microprocessor is a widely used 8-bit microprocessor that was developed by Intel. One of the important features of the 8085 microprocessor is its ability to support serial input/output (I/O) operations. The 8085 microprocessor has two dedicated pins, namely, the Serial Data I
5 min read
Registers of 8085 microprocessor Introduction : A microprocessor is a multipurpose, programmable, clock-driven, register-based electronic device that reads binary instructions from a storage device called memory, accepts binary data as input and processes data according to those instructions and provide results as output. A 8085 mi
8 min read
Introduction to 8051 Microcontroller 8051 is one of the first and most popular microcontrollers also known as MCS-51. Intel introduced it in the year 1981. Initially, it came out as an N-type metal-oxide-semiconductor (NMOS) based microcontroller, but later versions were based on complementary metal-oxide-semiconductor(CMOS) technology
8 min read
Operating Modes of 80386 Microprocessors The Intel 80386 microprocessor, often known as the i386, was a popular x86-based microprocessor. Its capacity to run in numerous modes, which allowed varied levels of memory management and protection, as well as backward compatibility with previous processors, was one of its primary characteristics.
3 min read