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The Intel (“eighty-eighty-five”) is an 8-bit microprocessor produced by Intel and introduced in It is a software-binary compatible with the more-famous. Microprocessor: It is a programmable electronics chip (Integrated Circuit ( IC)). A single IC has computing and decision making capabilities similar to. In addition to the microprocessor, a personal computer has a keyboard for The AS/ uses the PowerPC microprocessor with its reduced instruction set.

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The second address is where the data is stored. The contents of the memory location pointed out by microlrocessor stack pointer register are copied to the low-order register C, E, L, status flags of the operand.

A bus is a group of wires lines that carry similar information. Effective address is calculated by the processor and the contents of the address is used to form a second address.

Microprocessor Architecture

The ALU includes five flip-flops. The number of bits that can be stored in a register or memory element is called a memory word. These instructions control machine functions such as Halt, Interrupt, microprocesssor do nothing.

These instructions are used to transfer data from one register to another register, from memory to register or register to memory. A single IC has computing and decision making capabilities similar to central processing unit of a computer.

The is a conventional von Neumann design based on the Intel ALU includes the accumulator, the temporary register, the arithmetic and logic circuits and flags.

Intel – Wikipedia

The has extensions to support new interrupts, with three maskable interrupts RST 7. This distinguishes whether the address is for memory or IO. This signal is used microproccessor control READ operation of the microprocessor. During these transfers, the processor monitors the addresses on the bus and checks if any location modified during DMA operations is cached in the processor.


An immediate value can also be moved into any of the foregoing destinations, using the MVI instruction. While the pin goes low, the address micdoprocessor assigned for the memory. It always stores result of operations in Accumulator.

Subtraction and bitwise logical operations on 16 bits is done in 8-bit steps. This is an active low signal. Revision Notes for Digital Circuits Sep 24 52 upvotes. After the LCD process is over, the control is transferred back to analog and digital converter.

8085 Microprocessor Pin Diagram Explained

It is bidirectional, whereas address bus carries the location to where it should be stored and it is unidirectional. The sign flag is set if the result has a negative sign i. The instruction loads bit data in the register pair designated in the register or the memory.

Micropricessor three are masked after a normal CPU reset. The ALU performs the actual numerical and logical operations. This was typically longer than the product life of desktop computers. A number of undocumented instructions and flags were discovered by two software engineers, Wolfgang Dehnhardt and Villy M.

The architecture of consists of three main sections, 0855 Arithmetic and Logical Unittiming and control unit and Registers shown in the following figure.

These are nothing but the restart interrupts.


8085 Microprocessor Study notes for Electronics and Communication

Source operand is a data byte immediately following the opcode. At the end of data transfer, the controller terminates the request by sending a low signal to the HOLD pin, and the microprocessor regains control of the buses.

The system can now continue by selecting another process for execution, thereby utilizing the CPU cycles typically lost when using PIO. Data bus carries the data to be stored. Each instruction has two parts, one is task to be performed, called the operation code opcodeand the second is the data to be operated on called the operand.

These are the terminals which are connected to external oscillator to produce the necessary and suitable clock operation. It is fairly easy to implement, but requires the processor to constantly read or write a single memory word 8-bits, bits or bits, depending on the device interface until the data transfer is complete. After receiving the HOLD request, the Microprocessor relinquishes the buses in the following machine cycle. 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.

Used to accept data from outside devices to store in the accumulator or send the data stored in the accumulator to the outside device.