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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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Writes data or instruction into memory. The lower order address bus is added to memory or any external latch.

It controls the serial data communication by using these two instructions: The contents of the designated register pair point to a memory location. 80055 capability matched that of the competing Z80a popular derived CPU introduced the year before. The CPU is held in reset condition until this pin is high.

Pin Diagram and Pin description of 8085 Microprocessor

S0 and S1 are status signals which provides different status and functions depending on their status. It is a large and heavy desktop box, about a 20″ cube in the Intel corporate blue color which includes a CPU, monitor, and a single 8-inch floppy disk drive. The pins A8-A15 denote the address bus. The second address is where the data is stored.

It provides timing and control signal to the microprocessor to perform operations. 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. It is bidirectional, whereas address bus carries the location to where it should be stored and it is unidirectional.


All buses are tri-stated and a Hold Acknowledge signal is sent out. These instructions are used to perform arithmetic operations such as addition, subtraction, increment or decrement of the content of a register or memory. Consider we have an address to be processed. MVI A,00 ; Load immediate data into accumulator.

8085 Data-transfer Instructions

Subtraction and bitwise logical operations on 16 bits is done in 8-bit steps. Holds address, received from PC of next program instruction. Microproocessor, the architecture and instruction set of the are easy for a microproceasor to understand. The other six registers can be used as independent byte-registers or as three bit register pairs, BC, DE, and HL or B, D, H, as referred to in Intel documentsdepending on the particular instruction.

Data is provided through the registers. To communicate with memory the microprocessor sends an address on the address bus to the memory.

The result of an operation is stored in the accumulator. These are the terminals which are connected to external oscillator to produce the necessary and suitable clock operation. Week 8 Aug 27 30 upvotes. Such signals come under this category.

Classification of Signals The various signals in a microprocessor can be classified as Power supply and Frequency signals: This instruction copies the contents of the source register into the destination register without any alteration. MOV A, [[]] Implicit addressing: That is, they can be enabled or disabled using programs.


SIM and RIM mcroprocessor allow the global interrupt mask state and the three independent RST interrupt mask states to be read, the pending-interrupt mcroprocessor of those same three interrupts to be read, the RST 7.

These are intended to be supplied by external hardware in order to invoke a corresponding interrupt-service routine, but are also often employed as fast system calls. Which exam are you preparing for? In the previous article we saw how ALE helps in demultiplexing the lower order address and data bus. 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.

Pin Diagram and Pin description of Microprocessor

Each instruction is represented by 8 bit binary value. The zero flag is set if the result of the operation was 0. The same is not true of the Z Decoded instruction then passed to next stage.