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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In a three byte instruction, the first byte specifies the opcode and the following two bytes specify the bit address.

Pin Diagram and Pin description of Microprocessor

They insert an internal restart function automatically. The second address is where the data is stored. It is bidirectional, whereas address bus carries the location microprcessor where it should be stored and it is unidirectional. For example, multiplication is implemented using a multiplication algorithm. Accepts data from input device.

Microprocessor communicates with memory and other devices input and output using three buses: All 2-operand 8-bit arithmetic and logical ALU operations work on the 8-bit accumulator mucroprocessor A register.

The ALU performs the following arithmetic and logical operations. All three are masked after a normal CPU reset. Views Read Edit View history.

The ALU performs the actual numerical and logical operations. From Wikipedia, the free encyclopedia. The conditions set or reset of the flags are tested through the software instructions. 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.


Microprocessor Data-transfer Instructions

Processor completes the current bus cycle and then asserts the bus grant signal to microprocessoe device. Used to accept data from outside devices to store in the accumulator or microprocesxor the data stored in the accumulator to the outside device. The contents of the accumulator are copied into the memory location specified by the operand. It is an 8-bit microprocesso having five 1-bit flip-flops, which holds either 0 or 1 depending upon the result stored in the accumulator.

Some instructions use HL as a limited bit accumulator. The internal clock is available on an output pin, to drive peripheral devices or other CPUs in lock-step synchrony with the CPU from which the signal is output. Although the is an 8-bit processor, it has some bit operations.

Microprocessor – 8085 Architecture

The other six registers can be used as independent byte-registers or as three bit register pairs, BC, DE, and HL or Mkcroprocessor, D, H, as referred to microprocessoor Intel documentsdepending on the particular instruction. The pins A8-A15 denote the address bus. The device then asserts the bus grant ack signal. After the LCD process is over, the control is transferred back to analog and digital converter.

It has a bubble memory option and various programming modules, including EPROM, and Intel and programming modules which are plugged into the side, replacing stand-alone device programmers.

Processor acknowledges the bus release and resumes its bus cycles from the point it left off.


Among the interrupts of micropprocessor, TRAP is the only non-maskable interrupt. The only 8-bit ALU operations that can have a destination other than the accumulator are the unary incrementation or decrementation instructions, which can operate on any 8-bit register or on memory addressed by HL, as for two-operand 8-bit operations.

Although the data is still transferred 1 memory unit at a time from the device, the transfer to main memory now circumvents the CPU microprocessog the DMA controller can directly access the memory unit. 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.

Push the register pair onto the stack.

8085 Data-transfer Instructions

Address bus is unidirectional, i. Data bus also carries instructions from memory to the microprocessor.

This is provided by CLK pin. Power supply and Frequency signals: The result microprocessor an operation is stored in the accumulator. This signal goes high during the first clock cycle and enables the lower order address bits. The CPU is held in reset condition until this pin is high. If the processor detects a cached address on the bus, it can take one of the two actions: