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.

Author: Jusida Tumi
Country: Guadeloupe
Language: English (Spanish)
Genre: Software
Published (Last): 17 June 2004
Pages: 454
PDF File Size: 8.48 Mb
ePub File Size: 12.34 Mb
ISBN: 442-1-11910-751-6
Downloads: 1328
Price: Free* [*Free Regsitration Required]
Uploader: Dailkis

In a two-byte instruction, the first byte specifies the operation code and the second byte specifies the operand.

In this addressing mode the data itself specifies the data to be operated upon. The processor senses in the change in the state of bus grant ack signal and starts listening to the data and address bus for DMA activity. Writes data or instruction into memory.

Intel – Wikipedia

There are 6 general purpose registers in processor, i. Decoded instruction then passed to next stage. These signals are used for giving serial input and output data. It controls the serial data communication by using these two instructions: It points to a memory location in read-write memory, called the stack. Three control signals are available on chip: As in many other 8-bit processors, all instructions are encoded in a single byte including register-numbers, but excluding immediate datafor simplicity.

For two-operand 8-bit operations, the other operand can be either an immediate value, another 8-bit register, or a memory cell addressed by the bit register pair HL. Pin 39 is used as the Hold pin.

If it is high then IO operation and If it is low then Memory operation. Whenever the microprocessor receives interrupt signal. It is an 8-bit register having five 1-bit flip-flops, which holds either 0 or 1 depending upon the result stored in the accumulator. The contents of the register pair designated in the operand are copied onto the stack in the following sequence.


8085 Microprocessor Study notes for Electronics and Communication

After the LCD process is over, the control is transferred back to analog and digital converter. Exceptions include timing-critical code and code that is sensitive to the aforementioned difference in the AC flag setting or differences in undocumented CPU behavior. In many engineering schools [7] [8] the processor is used in introductory microprocessor courses. Microprocessor increments the program whenever an instruction is being executed, so that the program counter points to the memory address of the next instruction that is going to be executed.

Data bus carries the data to be stored. It has micgoprocessor lowest priority among the interrupts. After receiving the HOLD request, the Microprocessor relinquishes the buses in the following machine cycle.

Each instruction is represented by 8 bit binary value. Later an external box was made available with two more floppy drives. Output the data from the accumulator to a port with 8bit address. The size of the address bus determines the size of memory, which can be used.

This is a 3-byte instruction, the second byte specifies the low-order address and the third byte specifies the high-order address. Store the accumulator indirect. 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. INTR can be enabled or disabled by microprocesaor software. Exchange H and L with D and E.

Although the data is still transferred 1 memory unit at a time from the device, the transfer to main memory microprocessof circumvents the CPU because the DMA controller can directly access the memory unit. There are also eight one-byte call instructions RST for subroutines located at the fixed addresses 00h, 08h, 10h, The parity flag is set according to the parity odd or even of the accumulator. These are intended to be supplied by external hardware micgoprocessor order to invoke a corresponding interrupt-service routine, but are also often employed as fast system calls.


The lower order address bus is added to memory or any external latch. This signal is used miicroprocessor control READ operation of the microprocessor.

As the name suggests it controls the interrupts during a process. The same is not true of the Z Each register can hold 8-bit data. Adding HL to itself performs a bit arithmetical left shift with one instruction.

8085 Microprocessor Pin Diagram Explained

Note that, the micgoprocessor byte is the low-order address and the third byte is the high-order address. The instruction loads the contents of the H and L registers into the stack pointer register. Subtraction and bitwise logical operations on 16 bits is done in 8-bit steps. Retrieved 31 May Store H and L registers direct. Three status signals are available on chip: Load the register pair immediate.

Source operand is a data byte immediately following the opcode. It is bidirectional, whereas address bus carries the location to where it should be stored and it is microprcessor. Used to accept data from outside devices to store in the accumulator or send the data stored in the accumulator to the outside device. Microprocessor – Architecture Advertisements. It cannot be enabled or disabled using a program. All the above mentioned interrupts are maskable interrupts.

The instruction copies the contents of the memory location pointed out by the address into register L and copies the contents of the next memory location into register H.