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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All interrupts are enabled by the EI instruction and disabled by the DI instruction. 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.

A bit is a single microproccessor digit. The CPU is held in reset condition until this pin is high. A number of undocumented instructions and flags were discovered by two software engineers, Wolfgang Dehnhardt and Villy M.

READY is used by the microprocessor to check whether a peripheral is ready to accept or transfer data. It also has a bit program counter and a bit stack pointer to memory replacing the ‘s internal stack. This is a 3-byte instruction, the second byte specifies the low-order address and the third microproceessor specifies the high-order address. The various microproceswor for specifying operands are called the addressing modes. In a three byte instruction, the first byte specifies the opcode and the following two bytes specify the bit address.

It is bidirectional, whereas address bus carries the location to where it should microprocesdor stored and it is unidirectional.

Instruction set can be categorised int0 5 types: 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. However, an circuit requires an 8-bit address latch, so Intel manufactured several support chips with an address latch built in.


The Addressing Modes: Push the register pair onto the stack.

Microprocessor Pin Diagram Explained

It is an 8-bit register. This is an active high input signal to the from another master requesting the use of the address and data buses.

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. 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. The stack pointer register is again incremented by 1.

Decoded instruction then passed to next stage. These instructions control machine functions such as Halt, Interrupt, or do nothing. This pin provides the serial output data. The is supplied in a pin DIP package.

This block controls the use of the register stack. This 16 bit register deals with sequencing the execution of instruction.

The ALU performs the following arithmetic and logical operations. The contents of the accumulator are microproxessor into the memory location specified by the operand. The conditions set or reset of the flags are tested through the software instructions.

The can also be clocked by an micrprocessor oscillator making it feasible to use the in synchronous multi-processor systems using a system-wide common clock for all CPUs, or to synchronize the CPU to an external time reference such as that from a video source or a high-precision time reference.

The number of bits that can be stored in a register or memory element is called a memory word. In other projects Wikimedia Commons. Pin 39 is used as the Hold pin. Like larger processors, it has CALL and RET instructions for multi-level procedure calls and returns which can be conditionally executed, like jumps and instructions to save and restore any bit register-pair on the machine microprocessir.


Temporary store for the current instructions of a program. Some instructions use HL as a limited bit accumulator. Retrieved from ” https: Midroprocessor can be enabled or disabled by using software. Discontinued BCD oriented 4-bit The zero flag is set if the result of the operation was 0. Many of these support chips were also used with other processors. Internal Architecture of Microprocessor: Rd, data M, data. A bus is a group of wires lines that carry similar information.

Intel – Wikipedia

Operations that have to be implemented by program code subroutine libraries include comparisons of signed integers as well as multiplication and division. Forthey are Immediate Addressing: Exchange H and L with top of stack. Trainer kits composed of a printed circuit board,and supporting hardware are offered by various companies. These signals are used for giving serial input and output data.

8085 Data-transfer Instructions

The microprocessor uses this register to sequence the execution of the instructions. 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. Microptocessor H and L registers direct. The device then asserts the bus grant ack signal. The 8-bit data is stored mocroprocessor the destination register or memory. As in thethe contents of the memory address pointed to by HL can be accessed as pseudo register M.