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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A bus is a group 80055 wires lines that carry similar information. There are also eight one-byte call instructions RST for subroutines located microprodessor the fixed addresses 00h, 08h, 10h, It is an 8-bit register having five 1-bit flip-flops, which holds either 0 or 1 depending upon microproccessor result stored in the accumulator. In a two-byte instruction, the first byte specifies the operation code and the second byte specifies the operand.

Some of them are followed by one or two bytes of data, which can be an immediate operand, a memory address, or a port number. This unit uses the Multibus card cage which was intended just for the development system. It has the lowest priority among the interrupts. The size of the address bus determines the size of memory, which can be used.

By using this site, you agree to the Terms microprofessor Use and Privacy Policy. All buses are tri-stated and a Hold Acknowledge signal is sent out. Comments Write a comment. This was typically longer than the product life of desktop computers. These instructions control machine functions such as Halt, Interrupt, or do nothing.

Data bus carries the data to be stored. This indicates if any other device is requesting the use of address and data bus. After the request is completed, the control goes back to the main program.


8085 Microprocessor Study notes for Electronics and Communication

It points to a memory location in read-write memory, called the stack. A peripheral may be a LCD display or analog to digital converter or any other. Microprocessor – Architecture Advertisements. The stack pointer register is again incremented by 1.

Lastly, the carry flag is set if a carry-over from bit 7 of the accumulator the MSB occurred. Each register can hold 8-bit data. This is a 3-byte instruction, the second byte specifies the low-order address and the third byte specifies the high-order address.

Later an external box was made available with two more floppy drives. Operands are internal registers and are coded into the instruction. This pin provides serial input data. It always stores 805 of operations in Accumulator. Among the interrupts of microprocessor, TRAP is the only non-maskable interrupt. It has to be acknowledged. Which indicate that the selected IO or Memory device is to be read and data is available on the data bus. The is a binary compatible follow up on the INTR can be enabled or disabled by using software.

A bit binary number is called a word in a bit processor. The second address is where the data is stored.

Microprocessor – 8085 Architecture

This distinguishes whether the address is for memory or IO. Steps involved in the mode of DMA transfer are as follows. If it is high then IO operation and If it is low then Memory operation. Although the is an 8-bit processor, it has some bit operations.

Size of the data bus determines what arithmetic can be done. Many of these support chips were also used with other processors.


The function of the program counter is to point to microproceessor memory address from which the next byte is to be fetched. This is an active high output signal indicating that the MPU is relinquishing the control of the buses. The contents of the designated register pair point to a memory location.

Pin Diagram and Pin description of Microprocessor

The system bus is a group of wires used for communication between the microprocessor and peripherals. Once designed into such products as the DECtape II controller microprcoessor the VT video terminal in the late s, the served for new production throughout the lifetime of those products.

The microprocessor uses these flags to test data conditions. Week 8 Aug 27 30 upvotes.

Microprocessor Data-transfer Instructions

The incorporates the functions of the clock generator and the system controller on chip, increasing the level of integration. SIM and RIM also allow the global interrupt mask state and the three independent RST interrupt mask states to be read, the pending-interrupt states of those same three interrupts to be read, the RST 7. ALU includes the accumulator, the temporary register, the arithmetic and logic circuits and flags. The contents of the accumulator are copied into the memory location specified by the contents of the operand.

The contents of register L are stored in the memory location specified by the bit address in the operand and the contents of H register are stored into the next memory location by incrementing the operand. INTR is an interrupt request signal.