1. 1 Q.1) Draw & Explain the Pin-Diagram of Microprocessor in Detail? Ans: The Microprocessor is an 8-Bit general-purpose. is a 40 pin IC, The signals from the pins can be grouped as follows Power supply and clock signals,Address bus,Data bus Pin Diagram and Pin description of It is used to know the type of current operation of the microprocessor. Microprocessor – All concepts, programming, interfacing and applications explained.

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Pin diagram of – Microprocessor Course

This is a Read control signal active low. This signal goes high during the first clock cycle and enables the lower order address bits. This signal is used to control READ operation of the microprocessor.

Signals associated with the lower order address bus and time multiplexed higher order address bus comes under this type of signals.

Whenever INTR goes high the microprocessor completes the current instruction which is being executed and then acknowledges the INTR signal and processes it.

They have higher priority than the INTR interrupt. All the above mentioned interrupts are maskable interrupts.

A clock cycle is nothing but the time taken between two adjacent pulses of the oscillator. These pins are multiplexed to be used as address bus as well as data bus. Signals associated with data bus comes under this type. These 8 signal lines are unidirectional and used for most significant bits called higher order address bus of a bit address. They insert an internal restart function automatically. In the previous articles we saw about the architecture of microprocessor.


A peripheral may be a LCD display or analog to digital converter or any other. These pins are used for least significant bits of address bus in the first machine clock cycle and used as data bus for second and third clock cycle.

This is a non-maskable interrupt and has highest priority. It is ground reference. That is, they can be enabled or disabled micrpprocessor programs.

Signals which aids in supplying power and generating frequency are associated with this type. Whenever the microprocessor receives interrupt signal. In this article let us discuss in detail about the various signals involved in transferring data and executing instructions in microprocessor. Pin Diagram of Microprocessor and its description is as microprpcessor This pin provides the serial output data.

Pins like Vcc and ground are classified under this type.

This pin is used for hold acknowledgement. The lower order address bus is added to memory or any external latch. INTR can be enabled or disabled by using software.

In simple words clock cycle refers to the transition between o volts to 5 volts and back to 0 volts. S0 and S1 are status signals which provides different status and functions depending on their status. Power supply and Frequency signals: This is an active high, serial input port pin, used to accept serial 1 bit microprocsssor under software control. The serial data on this microprocfssor delivers its output to the seventh bit of the accumulator when SIM instruction is executed. This is a Write control signal active low.


Consider two peripheral devices. Suppose if analog to digital converter is using the address and data bus and if LCD requests the use of address and data bus by giving HOLD signal, then the microprocessor transfers the control to the LCD as soon as the current cycle is over. This pin resets the program counter to 0 and resets interrupt enable and HLDA flip-flops.

When the reset pin is activated by an external key all the internal operations are suspended and the program counter micro;rocessor cleared and the program execution begins at zero memory address.

The frequency is internally divided by two; therefore to operate a system at 3 MHz, the crystal should have frequency of 6 Mhz. These signals are used for giving serial input and output data. This signal is primarily used to synchronize slower peripherals with the microprocessor.

Microprocessor – 8085 Pin Configuration

READY is used by the microprocessor to check whether a pn is ready to accept or transfer data. Introduction In the previous articles we saw about the architecture of microprocessor. It has the lowest priority among the interrupts. While the pin goes low, the address is assigned for the memory. That is, an operation is performed when the signal goes low. It has to be acknowledged. Control and Status Signals: It cannot be enabled or disabled using a program.