In this note, we are going to learn about the Pin Diagram of 8085 Microprocessor or about its pin details or configurations. Welcome to Poly Notes Hub, a leading destination for Engineering Notes syllabus wise.

Author Name: Arun Paul.

What is 8085 Microprocessor?

Intel Corporation created the integrated circuit (IC) chip known as the 8085 processor. It is an 8-bit microprocessor, which means that the data it processes is divided into 8-bit segments. It was first introduced in 1976 and saw extensive use in a variety of electronic devices in the late 1970s and early 1980s, including industrial controllers, embedded systems, and personal computers.

📌 Some Important Key Features of this microprocessor:

Features	Description
8-bit Architecture	The 8085 is an 8-bit microprocessor, hence it processes data in 8-bit segments.
Instruction Set	It features a relatively simple instruction set of approximately 74 instructions. These instructions carry out basic arithmetic, logic, and data transfer tasks.
Clock Speed	The 8085 commonly ran at clock speeds of 2 to 3 MHz. Later versions and clones could achieve faster speeds.
Addressing Modes	Accessing memory and I/O devices is made flexible by the 8085’s support for multiple addressing modes, including register, indirect, and direct addressing.
Memory	Up to 64 KB of memory can be directly addressed by the 8085, while systems with less memory were frequently the result of peripheral and practical restrictions.
Peripheral Interface	It has integrated I/O support, which enables communication with peripherals like keyboards, monitors, and storage units.
Interrupts	Because the 8085 supports interrupts, external devices can handle urgent tasks by interrupting the microprocessor’s regular execution flow. Different types of interrupts in 8085: TRAP, RST (5.5, 6.5, 7.5), INTA, INTR, SID, and SOD.
Data and Address Buses	It features an 8-bit data bus and a 16-bit address bus, therefore it can address up to 64 KB of memory.

Pin Diagram of 8085 Microprocessor

Below we show the 8085 Microprocessor Pin Diagram or 8085 Microprocessor Pin Details –

Here’s a quick overview of the pin configuration of 8085 microprocessor –

1. VCC (+5V): This pin provides the supply voltage to the microprocessor. It requires a regulated +5V DC power supply for proper operation. It is basically the power supply pin of the pin diagram of 8085.
2. GND (Ground): Connected to the ground, this pin serves as the reference voltage for the microprocessor’s operation.
3. INTR (Interrupt Request): External devices can use this pin to send interrupt requests to the microprocessor.
4. RST 7.5 (Restart 7.5): This is one of the restart pins used to reset the microprocessor. It is a non-maskable interrupt and has the highest priority.
5. RST 6.5 (Restart 6.5): Another restart pin with lower priority than RST 7.5.
6. RST 5.5 (Restart 5.5): The third restart pin with even lower priority.
7. TRAP: This is the trap interrupt pin, which is used for non-maskable interrupt requests.
8. RST 5.5: The fourth restart pin with even lower priority.
9. SID (Serial Input Data): Used for serial data input to the microprocessor.
10. SOD (Serial Output Data): Used for serial data output from the microprocessor.
11. IO/M (Input/Output and Machine Cycle): This pin distinguishes between memory and I/O operations during machine cycles.
12. HLDA (Hold Acknowledge): Indicates that the microprocessor has received the HOLD request and is relinquishing control of the buses.
13. ALE (Address Latch Enable): Generates a signal to latch the address from the address bus during the first clock cycle of a machine cycle.
14. AD0-AD7 (Address/Data Bus): These lines carry both address and data information during various machine cycles.
15. A15-A8 (Higher Order Address Bus): These lines carry the higher-order address bits during memory and I/O operations.
16. S1 and S0 (Status): These pins indicate the status of the microprocessor during various operations.
17. WR (Write): This signal indicates a write operation from the microprocessor to an external device.
18. RD (Read): This signal indicates a read operation from an external device to the microprocessor.
19. READY: Indicates that the external device is ready to communicate with the microprocessor.
20. ALE (Address Latch Enable): Same as pin 13.
21. INTA (Interrupt Acknowledge): This signal indicates that the microprocessor has acknowledged an interrupt request.
22. RESET IN: This is the external reset input used to reset the microprocessor.
23. X1 and X2 (Crystal Oscillator Pins): These pins are connected to an external crystal oscillator that provides the clock signal for the microprocessor.
24. CLK (Clock): Provides the system clock input to the microprocessor.
25. RESET OUT: This is the reset output signal generated by the microprocessor to reset external devices.
26. Hold: This pin is used to pause the microprocessor’s operation temporarily.

In the above pin diagram of 8085 microprocessor, we describe every pin of the 8085 Microprocessor.